Download avstsspring2009handout

Association of Veterinary Soft Tissue Surgeons
Spring Scientific Meeting 1st April 2009
“What’s New and Hot?”
The AVSTS would like to thank the following sponsors for generously
supporting this meeting:
1
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
The Association of Veterinary Soft Tissue Surgeons
Hall 7, International Convention Centre, Birmingham, UK
1st April 2009
What’s new and hot?
PROGRAMME
--------------------------------------------------------------------------------------------------------------------------09:00 – 09:30 Registration/ Tea, coffee & pastries (provided)
09:30 – 11:00 Abstract session
 Emergency exploratory coeliotomy: retrospective
study of 189 cases
 Gastrointestinal foreign bodies in dogs and cats
 Total penile amputation and transpelvic urethrostomy
in a Staffordshire bull terrier
 Laparoscopic intrauterine artificial inseminations in
bitches using fresh and frozen thawed semen
 Simultaneous bilateral caudal superficial epigastric
skin flaps in a cat
 Biomechanical evaluation of different numbers,
sizes and placement configurations of ligaclips
required to secure cellophane bands
Page
Kelly Bowlt
5
Graham Hayes
Lea Liehman
7
8
Aracelle Alves
9
Sam Woods
10
Aiden McAlinden
11
Gary Ellison
12
11:00 – 11:15 Tea / coffee (provided)
11:15 – 11:55
11:55 – 12:05
Vacuum assisted wound closure: a new tool in the
management of troublesome wounds
Questions / discussion
12:05 – 12:30
AVSTS business meeting
12:30 – 13:20 Lunch in Hall 4 (provided)
13:20 – 13:40
Laparoscopy – abdominal exploration
Eric Monnet
17
13:40 – 14:20
Surgical trends in the obstructive jaundiced patient.
Stephen Mehler
23
14:20 – 14:40
Laparoscopy – liver.
Eric Monnet
26
14:40 – 14:50
Questions/panel discussion.
14:50 – 15:40
Translumenal intervention – are there no limits?
Rao Vallabhaneni
15:40 – 16:00
PSS – why use cellophane banding?
Eric Monnet
28
16:00 – 16:10
Questions
16:10 – 16:25 Tea/Coffee (provided)
16:25 – 17:05
Ectopic Ureters – burning or blading?
Stephen Mehler
31
17:05 – 17:25
Laparoscopy - cystoscopy.
Eric Monnet
33
17:25 – 17:30
Questions / panel discussion
Times subject to change
2
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Main Speakers
Gary W. Ellison, DVM, MS, Diplomate ACVS
Professor and Service Chief, Small Animal Surgery,
University of Florida Health Science Center, Gainesville, Florida
[email protected]
Dr. Ellison earned his DVM from the University of Illinois in 1975. He completed a small animal
internship at South Shore Veterinary Associates in Weymouth Massachusetts in 1976. Following this
he practiced general small animal practice in San Francisco California. He completed a residency in
Small Animal Surgery and received a MS in experimental surgery from Colorado State University in
1981. He practiced as a surgical specialist in San Diego California prior to becoming a Diplomate of
the American College of Veterinary Surgeons and joining the faculty of the University of Florida in
1983. He is author or coauthor on 70 refereed publications and PI or CoI on 25 funded grants. His
areas of interest include thoracic endoscopic and gastrointestinal surgery as well as feline renal
transplantation. He currently is Professor and Chief of Small Animal Surgery at the University of
Florida.
Eric Monnet, DVM, PhD, Diplomate ACVS
Dr. E
Department of Clinical Sciences
Colorado State University, Fort Collins, Colorado
[email protected]
Eric Monnet graduated from veterinary school in Maisons Alfort, France in 1985. He worked for four
years in a Paris private practice performing small animal medicine and surgery. In 1994, Dr. Monnet
completed a small animal surgery residency at Colorado State University and concurrently finished a
Master of Sciences degree. In 1997, Dr. Monnet received his PhD in Clinical Sciences studying
cardiac efficiency in dogs. In 2003, he became a fellow of the American Heart Association.
Dr Monnet is currently a professor in small animal surgery (soft tissue) at Colorado State University.
He has authored more than 100 articles and 15 chapters in various surgical textbooks. Dr. Monnet
was the founding president in 2001-2003 of the Society for Veterinary Soft Tissue Surgery. He is the
editor of the textbook: “Disease Mechanisms in Small Animal Surgery” (3rd edition).
3
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Steve J. Mehler, DVM, Diplomate ACVS
Assistant Professor of Small Animal Surgery
College of Veterinary Medicine, Michigan State University
Dr. Steve Mehler received his DVM from Michigan State University. He completed an internship in
small animal medicine and surgery and a small animal soft tissue, orthopaedic and neurologic surgery
residency at the University of Pennsylvania Veterinary Hospital. During his time at the University of
Pennsylvania, Dr. Mehler spent a considerable amount of time working with the special species
service. Dr. Mehler has published in many textbooks on surgical diseases of cats and dogs as well as
exotic species; including, Reptile Medicine and Surgery, Current Techniques in Small Animal Surgery,
Disease Mechanisms in Small Animal Surgery, Veterinary Clinics of North America, Trauma in Dogs
and Cats, and the BSAVA Manual. His research and clinical interests include minimally invasive
surgery, interventional radiology, medical and surgical interventions in exotics, and surgical diseases
of the extrahepatic biliary tract in dogs and cats.
4
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Emergency Exploratory Coeliotomy: Retrospective Study of 189 cases
(2001-2008)
Kelly Bowlt¹, Caroline Southerden, Stephen Baines²
1.
2.
Department of Clinical Veterinary Studies, University of Bristol, Langford House, Langford, Bristol, North Somerset, BS40
5DU.
Department of Clinical Veterinary Studies, Royal Veterinary College, Hawkshead Lane, North Mimms, Hertfordshire, AL9 7TA.
Introduction:
Emergency exploratory coeliotomy is indicated where there is an acute abdominal disease process
that requires surgery to provide a diagnosis, treatment and/or prognosis.
Materials and methods:
The medical records of 189 patients undergoing emergency exploratory coeliotomy at the Royal
Veterinary College between November 2001 and May 2008 were reviewed retrospectively.
Results:
The study comprised 152 dogs and 37 cats. Eleven animals (6.3%, 8 dogs and 3 cats) underwent
surgery for diagnostic purposes; 178 animals (93.7%, 144 dogs and 34 cats) underwent surgery for
therapeutic purposes.
Ultrasound was performed in 70 dogs (46.1%) and 21 cats (56.8%), contributing to a diagnosis in 68
(97.1%) and 16 (76.2%) cases. Radiographs of the thorax, abdomen or both were taken in 117 dogs
(77.0%) and 22 cats (59.5%), contributing to a diagnosis in 95 (81.2%) and 16 (72.7%) cases. Where
radiography was inconclusive, ultrasonography contributed to a diagnosis in 17/22 (77.3%) cases.
Clinical pathological information included biochemistry/haematology (133/185 abnormal), activated
partial thromboplastin time and prothrombin time (12/26 prolonged), FIV/FeLV (2/2 negative),
urinalysis (9/19 abnormal) and urine culture (1/7 positive).
The median time from admission to anaesthetic induction was 12 hours (range 0.75-672) and the
median surgical duration was 120 minutes (range 25-325), which was unrelated to species, age,
weight or survival (p>0.05).
One hundred and forty animals (74.1%) survived until discharge following a median hospitalisation of
4 days (range 1-20). Nineteen animals (10%) were euthanased intra-operatively and 30 (15.9%) were
euthanased/died following a median post-operative hospitalisation of 3 days (range 1-24). A greater
proportion of cats (17/37, 45.9%) than dogs (32/152, 21.1%) did not survive (P= 0.004). Survival was
less likely in animals undergoing surgery for diagnostic (8/11, 72.7%) rather than therapeutic (41/178,
23.0%) purposes (p<0.001).
Eighty-seven post-operative complications were seen in 71 animals (37.6%). Forty survivors (28.6%)
developed complications related to surgery (n=13), anaesthesia (n=5) or disease process (n=22).
Thirty animals were euthanased/died following complications related to surgery (n=3), anaesthesia
(n=4), disease (n=23) or concomitant disease (n=1).
Post-operative complications were more likely in older animals (P=0.014) or following longer surgical
procedures (P=0.005). Complications resulted in increased likelihood of death/euthanasia (p<0.001),
but were not related to either diagnostic or therapeutic surgery.
Clinical relevance:
54.1% of cats and 78.9% of dogs undergoing exploratory laparotomy survived until discharge.
Post-operative complications were more frequently associated with the disease process, increased
age or increased surgical duration, resulting in more deaths in cats than dogs.
5
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Table 1: Number of survivors/non-survivors, complications and final diagnoses of animals undergoing
emergency exploratory laparotomy (S Survivor; NS Non-survivor; DR Disease related complication;
AR Anaesthesia related complication; SR surgery related complication; UR unrelated complication).
Final Diagnosis
Dogs
Cats
Complications
(S/NS)
(S/NS)
DR (S/NS)
AR (S/NS)
SR (S/NS)
Septic peritonitis
11/11
4/6
4/5
0/2
1/0
Gastrointestinal foreign body
26/3
2/1
3/1
2/0
2/0
Gastric dilation/volvulus
31/5
0
5/4
3/1
4/0
Urethral rupture
1/0
0
1/0
Dystocia
9/0
0
1/0
Haemoabdomen
14/5
1/1
3/1
Uroabdomen
6/1
3/1
0/1
Diaphragmatic rupture
3/0
4/0
2/0
Intussusception
4/5
2/1
1/3
Pyometra
6/0
0
Neoplasia
1/1
1/0
0/1
Urethral calculi
2/0
0
1/0
Trauma
2/0
1/3
0/2
Bile peritonitis
1/0
1/1
1/1
Urethral obstruction
0
0/1
0/1
0/1
Exploration following wound
dehiscence
0
0/1
Orchitis
1/0
0
Mesenteric torsion
1/0
0
Splenomegaly
1/0
0
1/0
Biliary tract obstruction
0
0/1
0/1
No diagnosis achieved
1/0
0
1/0
Total
120/32
19/17
23/20
14/4
0/1
UR
(S/NS)
1/0
1/0
3/0
1/0
2/0
1/2
1/0
0/1
9/3
6
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Gastrointestinal foreign bodies in dogs and cats: a retrospective study.
Graham Hayes
RSPCA Greater Manchester Animal Hospital, 411 Eccles New Road, Salford M5 5NN
Objectives:
To establish predilection sites of obstruction and to investigate clinical factors associated
with a poor outcome.
Methods:
A retrospective study of 208 consecutive cases over a 48 month period from first opinion
practice.
Results:
Overall 91.3 per cent of cases recovered with higher survival rates from discrete foreign
bodies (94.2 per cent in dogs and 100 per cent in cats) as opposed to linear foreign bodies
(80.0 per cent in dogs and 62.5 per cent in cats).
English Bull Terriers, Staffordshire Bull Terriers and Jack Russell Terriers were overrepresented.
In dogs 62.6 per cent of obstructions occurred in the jejunum but foreign objects were
encountered at all points along the gastrointestinal tract.
A longer duration of clinical signs, the presence of a linear foreign body and multiple
intestinal procedures were shown to significantly increase mortality.
Neither the degree of obstruction (partial or complete) nor the location of the foreign body
were shown to have a significant influence on survival.
Clinical significance:
Prompt presentation, diagnosis and surgical intervention improves the outcome of
gastrointestinal obstruction by foreign bodies. At surgery the minimal number of intestinal
procedures should be performed to restore the integrity of the alimentary tract.
7
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Total penile amputation and transpelvic urethrostomy in a Staffordshire bull
terrier – a novel surgical technique
Lea M. Liehmann Dr.med.vet. DipECVS, Ronan S. Doyle DipECVS
Davies Veterinary Specialists, Higham Gobion, Hertfordshire, UK
An 8-year-old, male Staffordshire bull terrier presented with a bleeding mass in the urethral
mucosa 1.5 cm distal to the ischial arch.
Penile amputation, urethral resection and permanent urethrostomy have been described in
similar cases for the treatment of urethral obstruction or disease (Davis and Holt, 2003). A
perineal urethrostomy, however, requires at least a centimetre of remaining urethra distal to
the ischial arch that can be anastomosed to the perineal skin. This fact limits the level of
penile amputation and urethral resection. For conditions requiring a more aggressive
resection, prepubic urethrostomy has been described as a salvage procedure. However, this
has been associated with more postoperative complications such as urethral obstruction,
urine scalding, urinary incontinence and a higher likelihood of urinary tract infections
(Mendham, 1970, Kyles et al. 1996) compared to the more distal urethrostomies.
After confirmation of a bulging lesion during urethroscopy, we performed penile amputation
and urethral resection followed by a transpelvic urethrostomy using an ischial symphyseal
osteotomy. This allowed the urethra to be freed from its pelvic attachments, spatulated,
gently elevated and sutured to the overlying skin. A proximal tissue margin of one centimetre
was achieved.
A similar surgical technique has previously been described as a salvage procedure for failed
perineal urethrostomies in cats (Bernarde and Viguier, 2004) and was modified accordingly.
Postoperatively the dog showed no signs of incontinence or urinary tract infection at the 3
months recheck. Mild urine scalding was observed for 10 days after surgery, but resolved
afterwards. The excised lesion proved to be a vascular abnormality that had ruptured and
caused severe and prolonged bleeding.
References
Bernarde A, Viguier E. (2004): Transpelvic Urethrostomy in 11 Cats Using an Ischial
Ostectomy. Vet Surg 33:246-252.
Davis GJ, Holt D (2003): Two chondrosarcomas in the urethra of a German shepherd dog. J
Small Anim Pract: 44, 169-71.
Kyles AE, Aronson M, Stone EA (1996): Urogenital Surgery. In: Lipowitz AJ, Caywood DD,
Newton CD, Schwartz A (eds): Complications in Small Animal Surgery – diagnosis,
management, prevention. Williams and Wilkins, p.455-525.
Mendham JH. (1970): A description and evaluation of antepubic urethrostomy in the male
cat. J Sm Anim Pract 11: 709.
8
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Laparoscopic intrauterine artificial inseminations in bitches using
fresh and frozen-thawed semen.
Hotston Moore A1; Alves AE2, Apparicio MF2, Mostachio GQ2, Motheo TF2, Vicente WRR2
1. Department of Clinical Veterinary Sciences – University of Bristol – Bristol / United Kingdom
2. Faculty of Agrary and Veterinary Sciences, UNESP campus Jaboticabal – SP / Brazil
Artificial insemination has been an important technique in assisted reproduction for
wild species threatened with extinction. When intrauterine insemination is required the
laparoscopic technique has show benefits for this procedure be minimally invasive, reducing
the stress particularly in these species. The objective of this study was to compare fertility in
bitches, following intrauterine insemination by laparoscopy using fresh or frozen thawed
semen. Nine ejaculates from three males were used in a study of semen diluted in three
different protocols utilizing TRIS (Tris-hidroximetilaminometano), T1 – Tris +glucose; T2 –
Tris + fructose; T3 – Tris + Equex. T3 showed the best conditions of the spermatozoa post
thawing, and was choosing for use in the inseminations. During natural oestrus, 20 bitches
were inseminated on one occasion, 10 with fresh, and 10 with frozen-thawed semen. The
time point of the insemination was calculated according to the rise of plasma progesterone
levels. The bitches were subjected to general anaesthesia, and the laparoscopy technique
involved the establishment of pneumoperitoneum with a Verres needle positioned 1 cm
behind the umbilicus on the midline. A camera portal was placed 1 cm caudal to the
umbilicus and two instrument portals were placed 4 cm caudal at the umbilicus and 2 cm
lateral to the mammary glands, on either side. The uterus was grasped by forceps, and
elevated against the ventral abdominal wall. A 18g catheter was inserted through the
abdominal wall directly into the uterine lumen, and then 1.0 ml of either fresh semen
containing 200 x 106 spermatozoa/mL, or frozen-thawed semen containing 80 x 106
spermatozoa/mL was injected. Ovariohysterectomy was performed 7 days after
insemination, and the uterine tubes dissected and flushed using PBS solution in order to
evaluate the presence of embryos. A total of 7 and 5 bitches were pregnant from the fresh
and frozen-thawed semen group respectively. In conclusion laparoscopic intrauterine
insemination appears to be a practical technique that may be of value for management of
endangered species. In bitch, use of either fresh or frozen semen is effective.
9
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Simultaneous bilateral caudal superficial epigastric skin flaps in a cat.
S. Woods, A. I. de C. Marques, D. A. Yool
The University of Edinburgh, Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, Easter Bush Veterinary
Centre, Roslin, Midlothian, EH25 9RG
A 30 month old domestic shorthair cat was presented following unwitnessed trauma, with a
highly contaminated circumferential avulsion of skin from the right hind limb. Surgical
debridement was performed followed by daily dressing changes until the wound surface was
covered with healthy granulation tissue. Simultaneous bilateral caudal superficial epigastric
skin flaps were raised and used to cover the defect through a single bridging incision. Both
the donor and recipient sites were closed without tension at the wound edges.
Moderate oedema of the limb developed post-operatively but resolved within 72 hours of the
operation. The cat was weight-bearing on the limb 48 hours after surgery and sutures were
removed after 14 days.
The caudal superficial epigastric axial pattern flap is a highly versatile pedicle flap suitable
for closure of major skin defects over the caudal abdomen, the flank and the hind limb and
has been well described for use as a single flap. Mayhew and Holt (2003) reported the use
of simultaneous bilateral caudal superficial epigastric axial pattern flaps in the dog for an
extensive caudal flank and thigh wound but primary closure of the donor site was difficult
and required the use of skin expanders.
This is the first report of the use of simultaneous bilateral caudal superficial epigastric axial
pattern flaps in the cat to close an extensive circumferential hind limb wound, and
demonstrates that, unlike in the dog, donor sites can be closed easily.
Reference:
Mayhew, P.D. and Holt, D. E. (2003) JSAP 44, 534-538
10
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Biomechanical evaluation of different numbers, sizes and placement
configurations of ligaclips required to secure cellophane bands.
Aidan B. McAlinden, MVB, cert SAS, Conor T. Buckley, BA, BAI, PhD
and Barbara M. Kirby, DVM, MS, Diplomate ACVS, Diplomate ECVS
Objective:
To determine the optimal way to secure cellophane bands using ligaclips.
Study Design: In vitro mechanical evaluation.
Sample Population: Single-layer and triple-layer cellophane bands, 9.0mm and 11.5mm
ligaclips.
Methods: Triple-layer bands were secured with a different number (1-5), size (9.0 or
11.5mm) or configuration (linear or alternating placement) of ligaclips and mechanically
tested. Ultimate load was measured in Newtons (N). Ultimate load for single-layer and triplelayer bands secured with four alternating 11.5mm ligaclips were compared. Descriptive
statistics were reported as mean  SD with P<0.05 considered significant.
Results: Ultimate load was directly proportional to the number of ligaclips applied for the
linear configuration, but not for the alternating configuration, which began to plateau after
application of the fourth clip. Ultimate load for 11.5mm ligaclips was significantly higher
compared to the corresponding number of 9.0mm ligaclips for both configurations (P<0.05).
The ultimate load for ligaclips applied in an alternating configuration was significantly greater
than those applied in a linear configuration for both sizes (P<0.05 and P<0.01 for the 9.0mm
and 11.5mm ligaclips respectively). Ultimate load for four alternating 11.5 mm ligaclips
applied to triple-layer cellophane bands was significantly greater than the same configuration
applied to single-layer cellophane bands (P<0.01).
Conclusion: Triple-layer cellophane is recommended with an alternating configuration of
four 11.5 mm ligaclips.
Clinical Relevance: Surgeons should be aware that the number, size and configuration of
ligaclips and cellophane thickness should be considered to ensure optimal security of
cellophane bands and prevent slippage.
11
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
VACUUM ASSISTED WOUND CLOSURE: A NEW TOOL IN THE MANAGEMENT
OF TROUBLESOME WOUNDS
Gary W. Ellison, DVM, MS, Diplomate ACVS
University of Florida, College of Veterinary Medicine, Gainesville, FL
[email protected]
ABSTRACT
Vacuum-assisted wound closure (VAC) is a non-invasive, active, wound management
therapy exposing the wound bed to local sub-atmospheric negative pressure through a
closed system in order to facilitate wound healing. Initially introduced in human medicine for
the treatment of chronic wounds, VAC removes fluid from the extra vascular space,
improving circulation and enhancing the proliferation of granulation tissue.
A VAC system consists of several elements. Sterile polyurethane open-cell foam is cut to
conform to the surface of the wound. The foam is placed within the wound making sure the
foam is in contact with the entire wound surface. An egress tube runs from within the foam to
another tube, which is connected to a reservoir and a vacuum pump. A plastic sheet with
adhesive on one side is placed over the sponge and around the tubing creating an airtight
seal with the skin around the wound margin. Sub-atmospheric pressure then applies a
controlled suction force uniformly to all tissues on the surface of the wound.
Beneficial effects on wound healing have been documented in several animal models.
Reported benefits include increases in tissue blood flow, granulation tissue formation and
skin flap survival when compared to conventional bandaging techniques. VAC wound
dressings also demonstrate a significant increase in the rate of bacterial clearance in
experimentally infected.
The vacuum-assisted wound closure device and methodology are subject to United States
and foreign patents. A worldwide license for VAC has been assigned to Kinetic Concepts,
Inc. (KCI), San Antonio, TX. The VAC is a trademark of Kinetic Concepts, Inc.
APPLICABLE HUMAN LITERARY REVIEW
Non-Healing Wounds
Vacuum-assisted closure was initially developed for the non-surgical treatment of chronic
non-healing wounds in human patients. Of 175 patients with decubital ulcers treated with
VAC therapy 171 responded favourably resulting in complete closure or closure following a
less invasive skin graft or skin flap. In a study comparing VAC versus traditional wet-to-dry
bandages for the treatment of 36 chronic non-healing wounds, VAC treated wounds
decreased in size by 78% compared to a 30% size reduction in wounds treated with wet-todry bandages.
12
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Surgical Dehiscence
Vacuum-assisted closure has been used extensively in human surgery for the closure of
surgical dehiscence. The use of VAC therapy has been shown to decrease the wound
management time required before a delayed secondary closure could be performed. The
human literature also supports the use of VAC therapy in cases of surgical dehiscence with
exposed orthopaedic hardware, bone or tendons. The VAC system maintains these wounds
in a closed environment and enhances the rate of granulation tissue formation over exposed
bone, tendon or orthopaedic implant.
Skin Avulsions
Increased survival of skin flaps and skin avulsions injuries have been reported in both
human patients as well as various animal models. In veterinary patients, these injuries can
be difficult to manage since any attempt to stabilize the orthopaedic injuries often results in
further vascular compromise of skin, which is relying primarily on the sub-dermal plexus for
survival. The increased anatomic dead space and avascular tissue created by these
physiologic degloving injuries also create a favourable environment for bacterial growth.
Prevention of Post-Operative Swelling and Seroma Formation
In human surgical wounds associated with a high risk of seroma formation or post-operative
weeping, VAC dressings placed over the surgical incision at a low negative pressure (50 mm
Hg) have resulted in the prevention of seroma formation and the successful transition to a
dry wound that healed uneventfully with one 24-hour application.
Abdominal and Thoracic Uses
The VAC system has been used in human thoraces for the treatment of surgical dehiscence
following median sternotomy and abdominal cavities after damage control laparotomy and
for the treatment of abdominal compartment syndrome. Separation of the open celled foam
from the abdominal and thoracic viscera was performed in some cases with fenestrated
sheets of silicon. Enterocutaneous fistula formation has been reported as a result of foam
eroding through the serosal surface of the intestines. These enterocutaneous fistulas were
treated non-surgically with VAC using a series of progressively smaller foam pieces with
finer pore sized until the fistulous tracts were sealed and healed by second intention.
APPLICATIONS IN VETERINARY MEDICINE
Vacuum-assisted closure was first utilized at the University of Florida Veterinary Medical
Center in 2001 for the management of severe, traumatic degloving wounds in a tiger cub.
Since that time, we have utilized VAC extensively in the treatment of acute and chronic
wounds in dogs and cats. Initially, we used VAC in cases in which traditional bandaging and
wound management techniques had failed. As we gained confidence in the technique, VAC
became the initial treatment of choice for many wound conditions. We have found VAC
invaluable for the management of traumatic wounds prior to definitive closure or preparation
for skin grafting and in treatment of surgical dehiscence. We have also used VAC for the
13
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
treatment of chronic, problematic wounds and in the prevention of post-operative seroma
formation following orthopaedic procedures.
Traumatic Skin Wounds and Avulsions
We have used VAC to treat a variety of skin avulsions and physiologic degloving injuries,
many associated with severe musculoskeletal trauma. These injuries can be difficult to
manage in dogs and cats because any attempt to stabilize the orthopaedic injuries often
results in further vascular compromise of skin that is relying primarily on the sub-dermal
plexus for survival. The increased anatomic dead space and avascular tissue created by
physiologic degloving injuries also create a favourable environment for bacterial growth.
In cases were skin avulsion was associated with an open wound, the foam portion of the
VAC bandage was placed between the skin and subcutaneous tissues for approximately 3
days until healthy granulation tissue began to form. The foam was then withdrawn from
beneath the wound margin and placed over the remaining open wound surface to aid in
adherence of the avulsed skin to the underlying granulation bed. In several cases,
physiologic degloving occurred without an associated open wound. The skin in the avulsed
area was fenestrated and a VAC bandage applied over the fenestrated area. Skin
adherence to the underlying tissues occurred in most cases 3 to 4 days after initiation of
VAC therapy.
Abdominal and thoracic uses
We have used VAC for the treatment of septic peritonitis secondary to a dislodged PEG tube
in a diabetic dog. Following exploratory laparotomy and thorough lavage, a sterile
fenestrated sheet of plastic was sutured to each edge of the incised linea alba. Foam was
then placed within the abdominal incision and covered with the adhesive dressing. The VAC
bandage allowed the abdomen to remain open to aid in drainage while the airtight bandage
minimized the risk of potential secondary nosocomial infections. A fenestrated drain was
also placed within the dorsal abdominal cavity which allowed for intermittent abdominal
lavage. This dog was euthanized 2 days post-operatively due to continued deterioration of a
highly resistant Candida infection, however the techniques learned from treating an open
abdominal wound with VAC may be beneficial in future cases of peritonitis.
We utilized VAC therapy over an open thoracic cavity in a dog presenting with penetrating
bite wounds to the lateral chest and abdomen. The wounds had been closed primarily three
days prior, following which the dog had developed signs of septicemia. Exploration of the
wounds revealed a large defect and associated rib fractures with substantial necrosis and
contamination of the intercostals musculature, as well as pyothorax. The thoracic and
abdominal cavities were thoroughly lavaged and necrotic tissue debrided. The ribs were
apposed, while intentionally leaving an incomplete seal of the thoracic cavity. Foam was
then placed over the ribs and beneath the surrounding skin and the remaining VAC system
applied routinely. The VAC was set at -125 mmHg and functioned not only to provide
continuous suction to the wound, but to also drain the thoracic cavity. A thoracostomy tube
was also placed to ensure a reliable method of thoracic drainage, however was not needed
and was removed 48 hours after placement. The bandage was removed 3 days later and a
significant amount of granulation tissue was present. The wound was closed at this point
and the dog made a complete recovery.
14
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Complications and Contraindications
Few complications exist in the human literature regarding VAC therapy. The most common
is mild skin irritation from contact with the foam. The manufacturer has proposed several
contraindications to VAC therapy. Though the VAC system will debride wounds to some
extent, it will not remove grossly necrotic or devitalized tissue and should not be used in
place of proper surgical debridement. The VAC system should not be used in wounds
associated with known malignancies, since the application of the VAC bandage will likely
increase blood flow and stimulate cellular proliferation within the wound bed. The treatment
of osteomyelitis with the VAC system alone is also contraindicated. Though VAC can be
used over infected bone, resolution of osteomyelitis may be dependent on sequestrectomy
where indicated and appropriate antibiotic therapy as well. Finally, care should be taken
when placing VAC dressings near exposed arteries and veins. It is possible for the foam to
erode through vasculature resulting in extensive blood loss. Similarly, VAC dressings should
be used with caution in patients with coagulation abnormalities or patients with active
bleeding.
Addendum: Equipment and application of Vacuum assisted wound dressings in
veterinary medicine
It is essential that basic wound care principles be applied to all wounds prior to the
application of VAC therapy. Proper debridement of devitalized tissues is essential for
successful would closure and to eliminate any potential nidus for bacterial growth. Inability to
thoroughly debride wounds prior to the application of VAC may result in the proliferation of
granulation tissue over necrotic tissues resulting in delayed wound healing and abscess
formation.
A VAC system has several essential elements. Sterile open cell polyurethane foam, plastic
egress tubes, collection reservoirs and an adjustable suction pump capable of intermittent or
continuous negatives pressures ranging from –50 mm Hg to –200 mm Hg are all available
though Kinetic Concepts Inc.
The open cell polyurethane foam is used for the application. Each foam dressing comes in a
sterile package with two transparent plastic self-adhesive sheets. The foam can be cut to
conform to the shape of the wound. The foam should be placed within the wound so that it is
in contact with the entire wound surface especially the deep margins of the wound. Foam
should be placed within the wound fully expanded and care should be taken to avoid tightly
packing foam into wounds. Foam bandages available through KCI are often too large for
dogs and cats. The foam can be cut to shape and excess foam utilized in future VAC
bandages.
A plastic fenestrated egress tube is inserted into a hole cut into the foam or placed between
2 pieces of foam. Placement of the tube fenestrations directly on the wound should be
avoided as this may cause pressure necrosis in tissues around the fenestration sites and
result in clogging of the vacuum system. Once the foam and plastic tubing are in place the
two are then covered with an adhesive plastic sheet that extends several centimetres
beyond the wound margins. In veterinary patients it is helpful to cleanly shave all hair
surrounding the wound in order to facilitate adherence of the plastic sheet and establish an
airtight seal. In areas with difficult bandage conformation, we have also found it helpful to
15
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
apply stoma paste to the skin around the wound to aid in adherence of the skin to the plastic
adhesive sheet. It is essential that an airtight sealed be established in order to maintain
constant negative pressure and prevent desiccation of the underlying tissues. The egress
suction tube is then attached to a collection reservoir and to the vacuum pump. When the
bandage is properly placed, a closed system is created consisting of the wound, foam,
suction tube, collection reservoir and suction pump.
A continuous negative pressure setting of 125 mm Hg is most commonly used. Initial animal
studies showed improved blood flow and granulation tissue formation with intermittent
suction, however, when intermittent suction was performed in the clinical setting on human
patients, increased wound discomfort was noted. For weeping wounds and postoperative
prevention of seroma and oedema formation, a lower negative pressure setting of 50 mm Hg
is used.
The frequency of VAC bandage changes depends on the characteristics of the individual
wound. Vacuum-assisted closure bandage dressings are typically changed every 2 to 3
days. If VAC bandages are left in place over 4 to 5 days, granulation tissue may grow into
the open cell foam requiring surgical removal of the foam bandage. In veterinary patients,
bandage changes can often be performed under heavy sedation. If extended VAC therapy is
to be performed, the foam can be cut out through the plastic adhesive sheets while leaving
the portion of the sheet adhered to the skin in place. New adhesive sheets are placed over
the previously applied bandage to avoid pulling the adhesive sheet away from the skin.
16
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
LAPAROSCOPY
ABDOMINAL EXPLORATION
Eric Monnet, DVM, Ph.D., FAHA Diplomate ACVS,ECVS
Colorado State University, Fort Collins, Colorado
Laparoscopy is a minimally invasive technique for viewing the internal structures of the
abdominal cavity. The abdominal cavity is first distended with gas and then a rigid telescope
(laparoscope) is placed through a portal that has been positioned through the abdominal wall
to examine the contents of the peritoneal cavity. With the telescope in place, either biopsy
forceps or an assortment of surgical instruments can then also be introduced into the
abdomen through adjacent portals to perform various diagnostic or surgical procedures.
The minimal invasiveness of the procedure, diagnostic accuracy and rapid patient recovery
make laparoscopy often a preferred technique over other more invasive procedures. Small
animal laparoscopy initially evolved as a diagnostic tool but has progressed to where there is
now ever-increasing interest in the application of minimally invasive laparoscopic surgical
procedures.
INDICATIONS AND CONTRAINDICATIONS
Common indications for laparoscopy are to examine
and biopsy the abdominal organs or masses or to
perform surgical procedures. Laparoscopy may not
however always replace a complete abdominal
exploratory but provides a minimally invasive means of
accomplishing a number of diagnostic and surgical
procedures currently used in small animals (Table 1).
This list of indications has been evolving over time as
we learn more of the potentials of laparoscopy as a
diagnostics tool and as a means of minimally invasive
surgery.
Table 1. Basic Laparoscopic Techniques
Diagnostic
Liver biopsy
Cholecystocentesis
Pancreatic biopsy
Kidney biopsy
Intestinal biopsy
Adrenal evaluation
Splenic evaluation
Reproductive evaluation
Surgical
Feeding tube placement
Gastropexy
Ovariohysterectomy
Cryptorchid surgery
Gastric foreign body removal
Cystoscopy
Diagnostic laparoscopy is commonly used as a
method for obtaining liver, pancreas, kidney, splenic
and intestinal biopsies. It is generally accepted that laparoscopy provides better biopsy
tissues than other traditional percutaneous methods. Laparoscopy is also used in oncology
to diagnose and stage the extent of malignancy; either primary or metastatic. Full thickness
intestinal biopsies can also be performed using laparoscopic assistance. Other ancillary
diagnostic techniques include reproductive evaluation of the ovaries and uterus with the
capability for direct intrauterine insemination, gallbladder aspiration, splenic pulp pressure
measurements, laparoscopic directed splenoportography and urinary bladder evaluation.
Common surgical techniques currently being performed in small animals include cryptorchid
17
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
surgery, ovariohysterectomy, and prophylactic gastropexy. Other laparoscopic procedures
performed are cystoscopy, jejunostomy or gastrostomy feeding tube placement, abdominal
lavage tube placement, gastric foreign body removal and adrenalectomy. The potential for
laparoscopic surgery in veterinary medicine is limited only by our innovation and surgical
instrumentation available.
The many advantages of surgical laparoscopy over a conventional open surgical exploratory
laparotomy include improved patient recovery because of smaller surgical sites, lower
postoperative morbidity, infection rate and postoperative pain.
There are few if any contraindications of laparoscopy because of the minimal invasiveness
of the procedure. Often the patients that are a high risk for surgical exploratory actually may
become good candidates for a less invasive laparoscopic procedure. Ascites, abnormal
clotting times and poor patient condition are only relative contraindications. Ascitic fluid can
be removed prior to or during the procedure and has little influence over the probability of
success of the laparoscopy. Clinical experience suggests that abnormal clotting times may
not completely preclude performing laparoscopy.
Absolute contraindications for laparoscopy include septic peritonitis or conditions when
obvious conventional surgical intervention is indicated. Relative contraindications include
the patient condition, small body size or obesity. Patients that are either a poor anaesthetic
or surgical risk would obviously preclude performing the procedure. We have performed
laparoscopy on severely debilitated patients using only local anaesthesia and sedation in
which general anaesthesia and surgical laparotomy were considered to be too risky to the
patient. The procedure also becomes difficult in the very small patient (<2 kg body weight)
and in the very obese patient.
LAPAROSCOPIC EQUIPMENT
The basic equipment required for diagnostic laparoscopy includes the telescope,
corresponding trocar-cannula units, light source, gas insufflator, Veress (insufflation) needle
and various forceps and ancillary instruments (Table 2). Telescopes most frequently used in
small animal laparoscopy generally range in diameters from 2.7 to 10 mm. The 5 mm
diameter is adequate for most small animal procedures. The 0 degree designation means
that the telescope views the visual field directly in front of the telescope in180 degree
circumference.
Angled viewing scopes,
such as the most commonly used 30-degree
Table 2 Basic Diagnostic Laparoscopic Equipment
5 mm telescope (0 degrees)
telescopes, view in a down ward direction
2-cannulas
30 degrees from the telescope body. The
Veress needle
angled telescopes enable the operator to
light source
look over the top of organs and view in
light cable
small areas however this angulation also
CO2 insufflator
palpation probe
makes the orientation more difficult for the
oval biopsy forceps
inexperienced operator.
The telescope is next attached to a light
source using a light guide cable. It is
generally recommended that a high-intensity
punch biopsy forceps
grasping forceps
video camera and monitor
optional - photo documentation
18
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
light source such as xenon or halogen be used in laparoscopy especially if video or
photographic documentation is being incorporated. Xenon is considered to give the truest
colours of the abdominal organs and is recommended.
The endoscopic video camera is attached to the telescope and allows the image to be
viewed on a monitor rather than having to look directly through the telescope lens. Video
assistance is essential when performing surgical laparoscopy but not for simple diagnostic
techniques. Video guidance does however make laparoscopy much easier to learn and
perform and is recommended by the authors.
A Veress needle is used for initial insufflation of the abdominal cavity. The needle consists
of an outer sharp cutting tip and contained within the needle is a spring-loaded obturator that
retracts into the needle shaft as it traverses the abdominal wall and then advances beyond
the sharp tip after the needle enters the abdominal cavity. The hub of the needle is then
attached to insufflation tubing that has been attached to the automatic gas insufflator. Most
automatic insufflators are similar and function to dispense gas at a prescribed rate while
maintaining a predetermined intra-abdominal pressure. Carbon dioxide is the gas of choice
for insufflation because of the safety in preventing air emboli and spark ignition during
cauterization.
Following insufflation telescope and instruments are then placed through the abdominal
cavity using a trocar cannula unit that is of a corresponding size to receive either the
telescope or instruments. The trocar is a sharp pointed instrument and when housed in the
cannula is used to penetrate abdominal muscles and peritoneum. Once the trocar is
removed the cannula remains in place traversing the abdominal wall and becomes a portal
for introduction of the telescope or instruments into the abdominal cavity.
To perform diagnostic laparoscopy a number of accessory instruments are essential. They
are placed through a second cannula unit. A palpation probe is required to move and
palpate abdominal organs.
For diagnostic laparoscopy at least one biopsy forceps is essential. We find the 5 mm
diameter biopsy forceps with oval biopsy cups to be the most versatile and commonly used
for the liver, spleen, abdominal mass, and lymph node biopsy. A second biopsy instrument
is the punch type biopsy forceps and is often preferred by some for pancreatic biopsies.
Core biopsy needles and aspiration needles are also necessary for diagnostic laparoscopy.
One can also use long spinal needles for aspiration. A “true-cut” type biopsy needle is
required for both kidney and for deep tissue biopsies. Surgical laparoscopy often requires a
vast array of instruments designed for specific indications. Common instruments include
scissors, grasping forceps, and aspiration tubes and clip applicators. For surgical
laparoscopy in small animals 5 mm diameter instruments are commonly used however
certain specialized instruments such as stapling devices are generally 10 mm or larger in
diameter. Many of the biopsy and surgical instruments also have capabilities for monopolar
electrosurgery at their distal tip.
LAPAROSCOPIC TECHNIQUE
The first step in laparoscopy is to establish a pneumoperitoneum before cannula placement.
A small 2-mm skin incision is then made with a scalpel blade through the skin for placement
of the Veress needle. The entry site placement is either adjacent to the cannula portal sites
19
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
or in the same site to be used by the first telescope portal. The needle is then placed
through the abdominal wall by grasping the outer hub of the needle, so that the inner blunt
obturator is free to move into the needle as it passes through the abdominal wall. The blunt
obturator will then to spring into place once the peritoneum has been penetrated. One
should always assure that the Veress needle is in the abdominal cavity and is not retained in
the muscle planes of the abdominal wall or under the peritoneum. Inadvertent insufflation in
the subcutaneous tissues with CO2 makes the procedure almost impossible to continue.
To assure that the Veress needle is through the abdominal wall and in the abdominal cavity
one should both palpate with the needle tip on the inner surface of abdominal wall and by
using what is referred to as the “hanging drop test”. This test involves placing a drop of
saline in the hub of the Veress needle and then by lifting the abdominal wall with the needle
shaft the negative pressure within the abdominal cavity will pull the drop of saline into the
needle. This then assures that the needle is in the correct location and not resting into an
organ, abdominal wall or mass. Insufflation of gas into a mass, organ or vessel can result in
fatal air emboli. It is also important that the needle tip is also not placed deep within the
abdominal cavity. If the needle tip lies under the omentum during insufflation with gas the
omentum will balloon up and subsequently will obscure visualization when the telescope is
placed in the abdomen.
Next the insufflation line is attached to the Veress needle and the automatic insufflator is
turned on and the flow rate is set. When the abdomen is distended with CO 2 it will become
tympanic upon palpation. The abdominal pressure should be no greater than 15 mmHg. In
most all cases 10 mmHg is adequate to maintain abdominal distention and perform
laparoscopy in small animals. Intraabdominal pressures are shown on most all automatic
insufflators. Care should be taken not to over distend the abdomen with gas that will impair
abdominal venous return and excursions of the diaphragm.
A cannula unit that will receive the telescope is then placed through the abdominal wall.
First an incision is made through the skin large enough to accommodate the diameter
cannula. To assure the skin incision is the correct diameter one may make an imprint of the
cannula tip on the skin that can then be used as a template for the incision length. A
complete incision through all skin layers down to the subcutaneous tissues is required or it
will be very difficult to penetrate the abdominal wall. A hemostat can be used to open the
wound, assure the skin incision is the correct diameter and that it extends through all
cutaneous and subcutaneous tissues.
The trocar-cannula unit is then held with the trocar head firmly against the palm of the hand
to prevent the trocar from sliding back into the cannula as it is passes through the abdominal
wall. With the abdominal cavity adequately insufflated the tip of the trocar-cannula is placed
in the incision and using a twisting and thrusting motion the trocar is passed through the
abdominal wall. Immediately after abdominal entry the sharp trocar is removed from the
cannula to prevent possible organ trauma. The cannula can then be advanced deeper into
the abdomen. The Veress needle is then removed and the C02 line attached to the
insufflation stopcock of the telescope cannula.
Following the initial cannula placement the telescope is prepared for entry into the abdomen.
We recommend to first place the telescope in either a pan of warm sterile water or saline to
bring it to body temperature thus reducing the incidence of lens fogging when the telescope
20
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
enters the abdominal cavity. One should then assure the telescope lens is clean by wiping
the lens with a saline-soaked gauze sponge. The light cable is then attached to the
telescope and the light guide cable is handed to the assistant for attachment to the light
source. When using a video camera, the camera head is next attached to the telescope.
The light source, camera and monitor can now be turned on. The telescope is now
advanced through the cannula and into the abdomen.
With the telescope in the abdominal cavity, careful examination of the contents is then
performed. The site of entry for the second (accessory) portal is then selected. This
location is determined by the ancillary procedures that are to be performed. It is important
that the secondary cannula be placed far enough away from the telescope so that
manipulation of instruments is not hindered by the close proximity of the telescope and
second cannula. If an operator is right handed the operating cannula is generally placed to
the right of the telescope. When using both 5 mm telescope and accessory instruments it is
possible to switch telescope and instruments from one cannula to the other.
Abdominal exploration is begun using the palpation probe to “feel” and move the organs as
needed. A 5mm palpation probe with one-centimetre markings along the shaft is passed
through the secondary trocar cannula. As the probe or any instrument is passed into the
abdomen it should be viewed as it exits the cannula and it is then directed to the area of
examination.
Instruments should never be blindly passed into the abdomen and
manipulated until they come into view. This technique often results into serious tissue
trauma. All accessory instruments are passed into the abdomen using the same technique.
At the conclusion of the laparoscopic procedure the instruments and telescope are removed.
The pneumoperitoneum is removed by opening the cannula valves and permitting the CO2
to escape. The cannulas are then removed and the puncture sites are sutured in a routine
manner concluding the laparoscopic procedure. For postoperative pain management we
generally infiltrate bupivacaine local anaesthesia in the trocar cannula sites and prescribe
systemic analgesia for 12-24 hours following the procedure.
COMPLICATIONS OF LAPAROSCOPY
The complication rate of laparoscopy is low.
Potential complications are listed in table 3.
Serious complications include anaesthetic or
cardiovascular related death, bleeding, or air
embolism.
Complications resulting from either Veress
needle placement or trocar insertion include
injury to vessels in the abdominal wall,
penetration of organs or perforation of a
hollow viscus. Careful attention to technique
minimizes these concerns.
Complications also may occur during the
insufflation process.
That includes
subcutaneous emphysema if the Veress
needle is not through the abdominal wall or
Table 3. Potential Laparoscopic Complication
Anaesthesia related
Veress needle/trocar insertion
Injury to abdominal wall
Penetration of organs
Perforation of hollow viscus
Insufflation
Subcutaneous emphysema
Peritoneal tenting
Inappropriate insufflation
Pneumothorax
Gas embolism
Operative complications
Bleeding
Tissue injury
Technical problems
Lack of experience
Equipment related problems
21
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
peritoneal tenting if the needle lies under omentum during insufflation. With inappropriate
insufflation one is unable to visualize the abdominal cavity adequately making the procedure
much more difficult than necessary. Serious complications associated with insufflation
would be gas embolism in or pneumothorax. Gas embolism was reported during insufflation
in a dog when the Veress needle was inserted in the spleen. A pneumothorax will occur
either from accidental penetration of the diaphragm or from a diaphragmatic hernia.
Minor complications are generally operative associated resulting from one being unfamiliar
with the technique, the limitation and potential complications of a procedure or equipment.
Complications of surgical laparoscopy would be expected to be greater but thought to be
similar to the complications occurring with open surgical procedure. Cardiovascular and
respiratory complications can result from the positioning of the patient during
ovariohysterectomy for example. The abdominal organs compressing the diaphragm will
limit it’s the excursions. Utilization of a ventilator is required during such procedure to
prevent these complications.
SUMMARY
Laparoscopy is a minimally invasive technique for diagnostic and surgical procedures. Once
the basic technique of laparoscopy is mastered and the appropriate indications are applied
to the procedures it becomes a simple and rewarding addition to small animal veterinary
medicine and surgery. As our ability advances newer diagnostic and therapeutic procedures
will no doubt be developed.
22
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
SURGICAL TRENDS IN THE OBSTRUCTIVE JAUNDICE PATIENT
Steve J.Mehler, DVM, Diplomate ACVS
College of Veterinary Medicine, Michigan State University
Surgical diseases of the extrahepatic biliary tract in small animals are not uncommon. As we
are evolving into better diagnosticians and clinicians, we, as a profession are recognizing the
clinical signs of EBT disease more frequently and earlier than ever before. This
accompanied with technological advances in diagnostic and therapeutic modalities has
provided us with a unique opportunity to greatly impact the outcome of our patients with EBT
disease. However, a review of the recent veterinary literature provides a bleak insight to the
overall outcome of dogs and cats undergoing surgery for diseases of the extrahepatic biliary
tract. When study numbers are combined the overall survival rate for dogs is roughly
(140/220) 63.6% and for cats ~ (28/68) 41%. These numbers are appalling and should
provide a great impetus for us as scientists to ask, “why?”.
The assumption that surgery of the extrahepatic biliary tract (EBT) alone is the culprit behind
the high mortality rates continues to plague our profession. This thought process is
contributing to a worsening trend in outcome for our patients with EBT disease. A better
understanding of the normal physiology of the EBT and the pathophysiology of diseases of
the EBT accompanied by a more aggressive diagnostic and therapeutic approach to patients
with EBT disease may play a role in providing a better long term outcome for our patients
inflicted with diseases of the EBT. The common use of cholecystectomy to treat human
patients with non-obstructive cholelithiasis has significantly driven down the morbidity and
mortality rates in humans undergoing EBT surgery. Although veterinary medicine is lacking
in scientific evidence that a paradigm shift in how these patients should be dealt with, it is
likely that performing definitive surgical procedures early in the course of certain EBT
disease will provide a better long term outcome for our patients. When the data from dogs
with EBT obstruction are evaluated, there is a trend towards a linear correlation between
onset of clinical signs to surgery and outcome.
The poor outcome of small animal patients with EBT disease has led us as clinicians to seek
out other therapeutic avenues to treat these patients without pursuing surgery. A recent
collection of publications involving a small number of cases of patients with EBT obstruction
have provided some alternative techniques to surgery and mostly involve draining of the bile
via intermittent or continuous or cholecystocentesis until the cause of the obstruction has
resolved or until the patient is more stable for surgery. On a physiologic level, this does
decompress the liver; however, a major component of these patients’ systemic alterations is
due to the absence of bile within the small intestine. Although still controversial, more recent
human literature agrees that removing bile from the system, preoperative biliary
decompression, and many medical attempts at avoiding surgery for EBT disease has led to
prolonged hospitalization, increased morbidity, and in some instances, increases in mortality.
Granted, dogs and cats are not people and veterinary medicine is lacking in clinical evidence
that suggests one method over another, it would appear that early surgical intervention may
provide at least part of the solution to this long standing problem.
23
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
Frequently used surgical techniques for patients with EBT disease include; cholecystotomy,
cholecystectomy, choledochal stenting via duodenotomy, and cholecystoenteric
anastamosis. This abstract briefly reviews some less invasive approaches to EBT disease.
Choledochotomy
Choledochotomy and primary repair of extrahepatic biliary duct tears have been described,
but long-term outcome has not been extensively investigated. Described complications
include incisional leakage and subsequent bile peritonitis, stricture, and adhesion formation.
These surgical techniques are presented as alternatives or adjunct procedures which can be
considered as reasonable options.
Recently, Seven dogs and three cats with confirmed extrahepatic biliary tract obstruction
(EHBTO) were reported in abstract form to have had choledochotomies performed for a
variety of diseases. All dogs and cats were discharged from the hospital, and did not have
clinical recurrence of EHBTO.
Choledochotomy and primary repair of common bile duct tears are feasible surgical options
which should be considered if indicated for use alone or in conjunction with other procedures
when performing surgery to address EHBTO.
Percutaneous interventions (Minimally invasive versus minimalistic)
Percutaneous transhepatic cholecystocentesis and cholecystostomy tube placement have
been described in veterinary medicine in patients with EBT disease. These techniques are
used for both diagnostic and temporarily therapeutic alternatives to surgical sample
collection and definitive intervention. A major source of systemic illness in patient s with
EBT obstruction is the lack of bile salts in the small intestine. Simply put, bile salts not only
play an intricate role in fat and fat soluble vitamin absorption but also act as intestinal
detergents that bind bacteria and endotoxin. The lack of bile salts in the small intestine lead
to fat malabsorption, bacteremia and endotoxemia with secondary alterations in primary and
secondary hemostasis, renal dysfunction, decreased myocardial contractility, and depressed
activity of the reticuloendothelial system. Although percutaneous decompression of the EBT
allows for drainage of the intrahepatic biliary tract and decreases the backup unconjugated
and conjugated bilirubin in the serum it does not address the lack of bile slats in the small
intestine.
Percutaneous bile duct access and stenting
Access to the bile duct from this approach is not easy in dogs and involves sequential
dilation of the skin, body wall, liver parenchyma, and gall bladder wall to allow for access to
the bile duct and possibly the duodenum for stenting.
To avoid making a large hole in the liver or gallbladder, a small catheter and guidewire can
be used to gain access to the bile duct via percutaneous transhepatic gallbladder access.
The long wire is carefully guided into the duodenum and then grabbed by endoscopic
forceps within the proximal duodenum and pulled out of the mouth. The other end of the
wire is maintained outside of the patient. A stent can then be placed over the wire, down the
mouth, and across the major duodenal papilla as needed.
24
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
These techniques allow for decompression of the biliary tract and re-establish antegrade
flow of bile into the small intestine and are indicated in patients with EBT obstruction
secondary to pancreatitis and some tumours.
Endoscopic Retrograde Access (ERA)/Endoscopic Retrograde
Cholangiopancreatrography (ERCP)
Using a sideview flexible endoscope, retrograde access to the EBT becomes less
challenging. Using this specialized flexible endoscope, bile can be collected, positive
contrast studies of the EBT can be performed, and stents can be placed across the major
duodenal papilla. This technique is known to cause varying degrees of pancreatitis in
humans and dogs.
Rigid Endoscopic Retrograde Access (Lap Assisted Retrograde Access)
Using rigid endoscopic techniques, the distal duodenum is identified and exteriorized out of
the abdomen through a small incision in the skin and body wall. A 5mm cannula is placed in
the distal duodenum and directed orad. A 5mm rigid scope is then used to identify the major
duodenal papilla and wire access is achieved. Again, this technique can be used to collect
samples of bile, perform positive contrast studies, and place stents across the major
duodenal papilla. The major benefit of this technique is that biopsies of the pancreas, liver,
and full thickness bowel can be collected before or after biliary tract interventions.
Laparoscopic Cholecystectomy
In humans, laparoscopic cholecystectomy has been performed since the early 1980s and
represents the treatment of choice for gallstone disease and acute cholecystitis.
Approximately 75% of all human cholecystectomies are performed laparoscopically and
often on an outpatient basis. Operative safety is considered very high and conversion to
open surgery occurs in only 5–10% of cases. Laparoscopic cholecystectomy is useful in our
patients but at this time, patient selection remains the most important factor for success.
Patients with subclinical or mild clinical disease of nonruptured gallbladder mucocele and
without evidence of EBT obstruction are good candidates for this procedure. Also, the cat or
dog with nonclinical or intermittent signs associated with nonobstructive cholelithiasis may
prove to be good candidates for laparoscopic cholecystectomy.
References available upon request
25
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
LAPAROSCOPY
LIVER BIOPSY
Eric Monnet, DVM, PhD, FAHA, DACVS and ECVS
College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins,
Colorado
Laparoscopy is a minimally invasive technique for viewing the internal structures of the
abdominal cavity. Laparoscopy is simple to perform and considered to be safe having very
few complications. Despite the advent of newer laboratory tests, imaging techniques and
ultrasound directed fine needle biopsy or aspiration, laparoscopy remains a valuable tool
when appropriately applied in a diagnostic plan. Laparoscopy may also provide accurate
and definitive diagnostic and staging information that would otherwise only be obtained
through a surgical laparotomy.
Laparoscopic liver biopsy is considered by many to be a preferred method of obtaining a
liver biopsy. Other diagnostic modalities often do not provide sufficient enough information
on the liver. One is not only able to view the liver and but also adjacent organs as well. A
right lateral approach for evaluation of the liver, extrahepatic biliary system and right limb of
the pancreas is recommended. Using this approach one is able to examine over 85% of the
liver surface, take directed tissue biopsies and monitor for excessive bleeding. We
recommend using a 5 mm oval cup biopsy forceps for the liver. A recent study emphasized
the benefit of laparoscopic cup biopsies when two 18g needle biopsies were compared to
the laparoscopic cup biopsies.
Prior to liver biopsy the coagulation parameters are generally evaluated including a bleeding
time. Although coagulopathies are a relative contraindication of liver biopsy the coagulation
status does not necessarily predict if the patient will bleed from a liver biopsy.
The biopsy forceps are directed to the area of the liver to be sampled. Either an edge of the
liver or the surface of the liver can be biopsied with forceps. It is always important to biopsy 3
to 4 areas of the liver including areas that appear normal as well as abnormal. We generally
hold the cups tightly closed for approximately 15 to 30 seconds before pulling the sample
away from the liver. Some have suggested that biopsies taken at the edge of the liver may
not reflect pathology of deeper samples because the subcapsular tissues are more reactive
and fibrotic.
The biopsy area is then closely monitored for excessive bleeding. Generally most biopsy
sites bleed very little. If bleeding is considered to be excessive several steps should be
taken. First, the palpation probe can be placed into the biopsy site and pressure applied
over the area with the tip of the probe. Alternatively, a small piece of saline soaked GelFoam™ can be placed into the biopsy site using either laparoscopic grasping or biopsy
forceps. These options are sufficient to control excessive bleeding.
26
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
The gallbladder and extrahepatic biliary ducts can be evaluated also during laparoscopy.
Bile can be aspirated with a long spinal needle introduced through the abdominal wall. It is
important to place the needle behind the attachment of the diaphragm because if he needle
goes through the diaphragm it will induce a tension pneumothorax. The gallbladder is
deflated is deflated as much as possible to minimize the risk of leakage in the abdominal
cavity.
Laparoscopy is a minimally invasive technique for diagnostic and surgical procedures. Once
the basic technique of laparoscopy is mastered and the appropriate indications are applied
to the procedures it becomes a simple and rewarding addition to small animal veterinary
medicine and surgery. As our ability advances newer diagnostic and therapeutic procedures
will no doubt be developed.
27
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
PORTOSYSTEMIC SHUNTS: WHY USE CELLOPHANE BANDING?
Eric Monnet, DVM, PhD, FAHA, DACVS and ECVS
College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins,
Colorado
Portosystemic shunt (PSS) is an abnormal vessel that shunts portal blood from the
splanchnic circulation to flow directly to the systemic circulation by passing the liver.
Toxins, hormones, nutrients, escaping bacteria, and exogenous drugs also bypass the liver
resulting in hepatic encephalopathy (HE). Hepatic growth and size are maintained by normal
portal blood flow (80% of the total liver blood flow) and hepatotrophic hormones (insulin,
glucagon). Diversion of portal blood flow results in atrophy of the liver inducing further
deterioration of liver function. Dogs or cats with congenital portosystemic shunt present with
multiple clinical signs related to HE. Differentiation between single congenital and multiple
acquired shunts is important, as their treatment and prognosis differ greatly. Treatment of
choice for congenital shunt is partial or complete surgical ligation of the anomalous vessel;
this may result in fatal portal hypertension in patients with acquired shunt. Portal
hypertension secondary to primary liver disease (i.e. hepatic cirrhosis) result generally in the
development of acquired shunts.
Congenital portosystemic shunts may be classified as single or multiple and intrahepatic or
extrahepatic. Five types of PSS have been described. Eighty percent of the PSS are single,
72% are extrahepatic, and 95% are between the portal vein and the caudal vena cava.
Surgery is recognized as the treatment of choice for PSS. Because liver needs
hepatotrophic substances from portal blood flow, deterioration of liver function can be
expected if the shunted blood flow is not surgically corrected in a physiologic direction.
Medical treatment will not correct this alteration, therefore long term survival is not expected.
In one study, only 2 of 8 dogs with medical treatment were still alive at 6 months. Life
expectancy of 2 months to 2 years is generally reported; the actual time presumably being
dependent on the amount of portal blood flow. Restoring the flow of hepatotrophic
substances to sinusoidal milieu results in substantial hepatic regeneration and reversal of
functional impairment.
Patients with PSS experience a reduction in absorption, metabolism, and clearance of drugs
due to liver impairment. Fentanyl can be used for sedation. Mask induction with isoflurane
followed by endotracheal intubation is the method of choice. Dextrose (2.5%) is important
during surgery and the immediate postoperative period to maintain blood glucose.
Cephalosporin perioperatively is recommended. Ischemic episode can occur in the bowel
during manipulation of the PSS that may result in bacterial embolization.
A standard ventral midline coeliotomy is performed from the xiphoid to pubis to explore the
portal system. The portal vein and caudal vena cava are located by retracting the duodenum
medially. The portal vein is identified ventral to the caudal vena cava at the most dorsal
aspect of the mesoduodenum. The caudal vena cava is examined for identification of any
abnormal blood vessels. Normally, from the renal and phrenicoabdominal veins to the hilus
of the liver there should be no blood vessels entering the caudal vena cava ventrally. Any
28
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
blood vessel in this area should be suspect as an extrahepatic shunting blood vessel.
Turbulence in this portion of the vena cava is another important clue for locating a possible
shunt. If nothing abnormal is noticed the left omental bursa is entered and all tributaries from
the portal vein are identified. Most often, shunting vessels come from the gastrosplenic vein
in dogs and left gastric vein in cats. If no shunting vessel can be located, investigation for an
intrahepatic shunt is started. Inspection of the hepatic veins cranial to the liver and
inspection of liver lobes for dilation are the first steps in identification of an intrahepatic
shunt.
Complete occlusion of the shunt at the time of surgery is associated with a better prognosis.
However, complete occlusion may not be possible at the time of surgery because the liver
parenchyma cannot accommodate the augmentation in blood flow. It then results in portal
hypertension. Occlusion of a PSS has been performed traditionally with a suture placed
around the shunt and tight while the portal pressure was measured. This technique resulted
in acute or chronic portal hypertension in 15 to 20 % of the cases. Acute portal hypertension
resulted in death in most of the cases. Chronic portal hypertension induced ascites and the
opening of acquired shunts.
To palliate to these problems and achieve complete occlusion of the PSS gradual occlusion
has been performed with ameroid constrictor or cellophane band. Both of these devices
induce a slow and complete occlusion of the PSS over 4 to 8 weeks. The liver parenchyma
can then accommodate the augmentation in blood flow without inducing portal hypertension.
A strip of cellophane 1 cm wide is folded three times on itself. It is then placed around the
shunt vessels without inducing any occlusion of the shunt. The cellophane is stabilized with
a vascular clip. There is no need to partially occlude the shunt vessel to a diameter less
than 3 mm. Partial occlusion might even be detrimental for the patient in the long term.
Cellophane band is light and can be placed like a suture. It does not require an extensive
dissection around the shunt to be placed. Since it is light, there is no risk to induce an acute
complete occlusion of the shunt because of weight shifting.
Postoperatively, patients are examined for signs of portal hypertension: sepsis, abdominal
pain, bloody diarrhea, and ascites. If signs of portal hypertension occur, the patient is taken
back to surgery and the suture released. Failure to remove the ligature will result in septic
shock and death. Hypothermia during surgery and postoperatively should be corrected
aggressively. Dextrose (2.5%) intravenously is maintained. Thrombosis of the portal vein has
been reported as complication of a partial ligation of intrahepatic PSS. Postoperative
seizures have been reported as a complication of ligation of PSS and they carry a poor
prognosis. Seizures may occur immediately or up to 3 days postoperatively.
Surgical mortality associated with treatment of PSS can be as high as 20 %. The
intraoperative and immediate postoperative periods are most critical. Hypothermia and
hypoglycemia should be anticipated and treated promptly. With the devices for gradual
occlusion the incidence of complications seems significantly reduced.
Post-operatively the animals should be maintained on a low protein diet, amoxicillin or
neomycin, and lactulose. Bile acids should be monitored at one, three and six months after
surgery. Lactulose should be interrupted one month after surgery. The antibiotics should
then be removed from the treatment. Three months after surgery the diet can be
progressively return to normal. If the animal is showing signs of hepatic encephalopathy
then the low protein diet is re-instituted.
29
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
With cellophane bile acids do not come to within normal limits before 3 to 6 months after
surgery. The cellophane is inducing a slow and progressive occlusion of the shunt. A slow
progressive occlusion of the shunt seems to decrease the risk of developing acquired shunts
like ameroid ring has been.
30
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
CYTOSCOPIC LASER ABLATION OF ECTOPIC URETERS (CLA)
Steve J.Mehler, DVM, Diplomate ACVS
College of Veterinary Medicine, Michigan State University
Ectopic ureters are a common congenital anatomic deformity in dogs with the ureteral orifice
being positioned distal to the bladder trigone within the ureter, vagina, vestibule or uterus.
Ectopic ureters can create a significant dilemma as one considers various approaches to
both diagnosis and treatment. Interventional radiologic and interventional endoscopic
techniques have aided in the ability to simultaneously diagnosis treat ectopic ureters in a
minimally invasive fashion.
Equipment needed includes flexible (7.5-8.2 French) and rigid (diameters range from 1.9 mm
to 7.5 mm) endoscopes, different types of intracorporeal lasers are available for this
procedure including Holmium:YAG and diode. A fluoroscopic C-arm is sufficient for
visualization and ureteral intervention, and is useful for this procedure, but is not necessary.
Various guidewires and catheters are also needed for each procedure. Ureteral stents in
numerous shapes and sizes (double pigtail, locking loop pigtail, or nephroureteral stents) are
soft polyurethane catheters that can be easily removed after resolution of ureteral disease.
These stents are typically not needed for this procedure unless complications occur.
I prefer the use of a Holmium laser for this procedure. The holmium laser, being a longpulsed laser, creates thermal interactions with tissue. This makes it useful for both laser
lithotripsy and soft tissue ablation. The holmium laser has a wavelength of 2100 nm making
the laser beam invisible. Anyone in the room while the laser is in use should wear
appropriate laser safety eyewear specific to the wavelength of the laser, even if the
procedure is being done endoscopically. The routine settings used for CLA by the author
are:
Energy (Joule) 0.80
Rep. Rate (Hz) 10
Average Power (watts) 8
Fibre size (um) 400
Pulse width (us) 700
Under general anaesthesia, via cystoscopy and, if available, fluoroscopy, an angle-tipped
hydrophilic guidewire (Weasel® wire, Infiniti Medical) is advanced retrograde into the
ureterovesicular, ureterourethral, or ureterovaginal junction, up the distal ureter and curled
into the renal pelvis or left in the proximal ureter. A ureteral catheter is then advanced over
31
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
the wire under fluoroscopic or cystoscopic guidance, and the guidewire is removed. A
retrograde contrast ureteropyelogram can be performed, if needed, to help identify any
lesions, filling defects, dilations, tortuosity of the ureter, ureter diameter, or other
abnormalities in the ureter or renal pelvis. This is the typical approach for female and large
male dogs. In small male dogs a combined retrograde and laparoscopic assisted antegrade
approach can be used for visualization, diagnosis, and treatment.
Retrograde positive contrast ureterograms allow for adequate visualization of the ureters
without the risk of extravasation of contrast in the retroperitoneal space (i.e., antegrade
pyelography) and prevents the risk of contrast induced nephropathy or Ig mediated systemic
reactions (EU or IVP), since the contrast agent remains in the renal collection system and is
not injected intravascularly.
Once the ureteral catheter is in place, the laser fibre is pushed out of the tip of the instrument
channel on the cystoscope. The aiming beam is turned on (green or red). The aiming beam
is aimed at the area of interest, which is the most distal aspect of the abnormal ureter. The
laser is only fired on top of the ureteral catheter so that the lower urinary tract wall is not
penetrated. The most ventral aspect of the ureteral trough should be laser ablated from
distal to proximal until the opening is within in the bladder neck. If the wall is penetrated it is
possible to finish the CLA and recover the patient with a urinary catheter in place for a few
days to allow the hole to heal. A contrast cystourethrogram or repeat cystoscopy should be
performed before discharging the patient from the hospital. Ectopic ureters are a common
congenital anatomic deformity in dogs with the ureteral orifice being positioned distal to the
bladder trigone within the urethra, vagina, vestibule or uterus. Over 95% of dogs with ectopic
ureters transverse intramurally and are candidates for this minimally invasive procedure.
This procedure is often performed on an out-patient basis at the time of cystoscopic
diagnosis, avoiding the need for more than one anaesthetic procedure for definitive therapy.
Overall, surgical fixation of intramural and extramural ectopic ureters reports results of
continued incontinence with concurrent medical intervention in anywhere from 40-71% of
cases. Endoscopic repair of ectopic ureters has been performed in over 50 dogs
successfully at 4 institutions in the United States. Thus far, in the combined experience of
the University of Pennsylvania and Michigan State University, continence has been
maintained in 80% of patients and 100% of male dogs are reported to be immediately
continent. If the University of Pennsylvania patients are evaluated alone, continence has
been maintained in 87.5% of patients either with (25%) or without (62.5%) concurrent
medications (Allyson Berent, pers com). This procedure is successful in both male and
female dogs with intramural ureteral ectopia, avoiding laparotomy, cystotomy, urethrotomy
and ureterotomy.
32
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
LAPAROSCOPY
CYSTOSCOPY
Eric Monnet, DVM, PhD, FAHA, DACVS and ECVS
College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins,
Colorado
There are a number of minimally invasive surgical (MIS) procedures that are
currently performed using laparoscopy. Many of these procedures require multiple
trocar/cannula portals, specific minimally invasive surgical instruments, loop ligatures, clip
applicators and monopolar electrosurgery.
Laparoscopic cystoscopy is an alternate method that allows placement of a
laparoscopic telescope into the urinary bladder that has been exteriorized through the
abdominal wall for examination, biopsy and calculi removal.
Prior to surgery, a urinary catheter is placed. The catheter is then connected to a
bag of saline in a pressure bag. The technique involves a standard laparoscopic entry with
the telescope placement on the abdominal midline caudal to the umbilicus. Once the urinary
bladder is visualized a second trocar cannula is placed directly over the urinary bladder at
the location of exteriorization. The bladder has to be under slight tension to create a straight
tube to prevent stones to accumulate in dorsal pocket of the bladder. Using atraumatic
forceps with multiple teeth the bladder is grasped and pulled into the trocar cannula as
described in intestinal biopsy section. Once the apex of the bladder is exteriorized stay
sutures are placed from the bladder wall. The bladder is temporally pexied to the abdominal
wall. A small incision is made in the bladder wall, and a 5 mm cannula is introduced in the
bladder. A suction line is connected to the cannula. The bladder is then flushed with sterile
saline under pressure and the suction on the cannula. The telescope is introduced into the
bladder. Bladder stones are usually suctioned with the cannula by the combine effect of
suction and flushing. Forceps can be placed in the bladder along the telescope to obtain a
biopsy or remove calculi. At the conclusion of the procedure the bladder is closed in a
standard manner. The pexy is released and the abdomen closed in a routine fashion.
Laparoscopy is a minimally invasive technique for diagnostic and surgical procedures. Once
the basic technique of laparoscopy is mastered and the appropriate indications are applied
to the procedures it becomes a simple and rewarding addition to small animal veterinary
medicine and surgery. As our ability advances newer diagnostic and therapeutic procedures
will no doubt be developed.
33
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”
34
AVSTS Pre-BSAVA meeting 2009 “What’s New & Hot?”