Download Anal sacs: a new approach to an old problem?

VETERINARY PRACTICE JANUARY 2016
DERMATOLOGY
31
Anal sacs: a new approach to an old
problem?
THERE are numerous reasons why
dogs will “scoot” on their bottoms
but the most common of these is an
attempt for them to empty their anal
sacs.
Whilst we are uncertain what
opportunities veterinary
undergraduates get
to hone their anal sac
emptying skills before
they qualify, there is no
doubt that the frequent
requests from dog owners
to perform the ritual
emptying during routine
small animal consultations means
that it doesn’t take long for them to
become highly adept at the art of anal
sac evacuation once they do get their
coveted MRCVS.
What are anal sacs and why do they
fill up? Anal sacs, sometimes mistakenly
referred to as anal glands, are two
small structures located between the
internal and external sphincter muscles.
Each sac is lined with both sebaceous
and apocrine glands whose combined
secretions produce a semi-oil foul
smelling brown liquid.
As the anal sphincter muscles expand,
as defaecation occurs, pressure on the
sacs leads to the expulsion of their
contents over the faeces. Problems arise
when this emptying process does not
occur and the secretions build up in the
sac, causing obvious discomfort to the
dog.
There is very little high-quality
information as to why anal sacs
“overfill”. Suggested reasons include
change in the character of the secretion,
excessive secretions, soft faeces or
diarrhoea, poor muscle tone and
obesity. Poodles, Chihuahuas and Lhasa
apsos are said to be at increased risk of
developing anal sac disease although
most of this information is anecdotal.
The more difficult question to
answer is how often should anal sacs be
emptied and when if ever should they
be packed or removed? When anal sacs
are emptied it is important this is done
per rectum.
Briefly, a gloved, lubricated finger
Sue Paterson, MA, VetMB, DVD,
DipECVD, MRCVS, RCVS and
European Specialist in Veterinary
Dermatology, is at Rutland
House Veterinary Hospital, St
Helens, Merseyside.
Stephen Steen, MSc, FIBMS,
CHS (ABHI), is laboratory
manager and microbiology
adviser at CAPL/NWL Knutton,
Staffs.
should be inserted into the anus.
Gentle pressure should be applied
against a juxtaposed thumb. The
discharge should be collected onto
clean cotton wool. A bacteriology
swab or cytology can be taken from
the cotton wool.
The empty sac should be palpated
to check for swelling and to assess the
anal sac cytology from normal and
diseased sac. Studies by Lake (2004)
and Robson (2003) suggest neutrophils
and erythrocytes are rarely found in
normal anal sac cytology. Lake’s paper
also suggests the characteristics of
the discharge can be very variable in
normal animals and that the colour,
consistency and quantity of secretions
can give little
SUE PATERSON and
clue as to the
STEPHEN STEEN review this
status of the
common problem, including
gland.
how often they should be
A more recent
emptied, and discuss some
study by James
of the misconceptions about
(2010) also
antibiotics to use for infections
showed that
dogs with anal
thickness of the walls. The perianal
sac disease do have more neutrophils
area should be cleaned with dilute
on cytology than normal dogs;
antiseptic and the procedure should
however, the increased frequency of
be repeated on the other side.
neutrophils in affected dogs was not
When the walls of a normal anal
found to be statistically significant.
gland are palpated between finger and
That same study suggested there was
thumb they should feel smooth and
no cytological difference between anal
the thickness of a balloon. Where
sac cytology from normal dogs and
there is chronic hyperplastic change in those with anal sac disease. However,
the wall or there is neoplasia they feel
many of the dogs in this study needed
thickened and leathery.
their anal glands emptying (evidenced
One possible progression of the
by a return to “bottom scooting”) after
disease process is outlined in the flow only seven days, suggesting that their
chart – Figure 1.
perianal pruritus may have been caused
Clinical decisions as to when
by other factors.
over-full anal sacs progress to anal
Where relief of pruritus is so
impaction, anal sacculitis, and then
short-lived, perianal allergy must be a
anal sac infection and abscessation,
significant alternative reason for the
are challenging and must rely on
“bottom scooting” (Maina, 2014).
history, clinical examination, cytology
Important factors in the history that
and where necessary culture.
suggest the problem is related to anal
In Hedlund and Fossum’s Small
sac disease are summarised in Table 2.
Animal Surgery they suggest that anal
Whilst the authors would accept that
sacculitis is diagnosed when moderate the presence of bacteria, erythrocytes
or severe pain is elicited on palpation
and neutrophils on cytology could
and secretions are liquid yellow, blood be suggestive of anal sac disease, a
tinged or purulent. Cytology, they
diagnosis should only be made when
suggest, reveals cellular debris, large
other criteria are included. The authors
numbers of leukocytes and numerous would suggest at least three out of four
bacteria.
of the criteria in Table 2 should be
Several studies have compared
present to suggest anal sac disease.
Figure 2. Cytology from anal gland
showing inflammatory infiltrate with
rods and cocci.
Figure 3. Cytology from anal gland
showing rods and cocci but no
inflammatory infiltrate.
Figure 4. Anal sacs may be flushed
and then packed with an antibiotic
solution.
Where dogs are re-presented on a
regular basis to have their anal sacs
emptied, and where abnormalities are
detected, then it is often beneficial to
flush and pack the sacs. Where such a
procedure fails to resolve the problem
then anal sac removal may be necessary.
There are many misconceptions as to
the best antibiotics to use for anal sac
infections. The authors examined the
Full anal sacs
discharge from 20 normal anal sacs of
10 dogs considered not to be diseased
Impaction – sacs need to be emptied
monthly
or
more
frequently

(based on the criteria in Table 2) and
Impacted anal sacs
20 anal sacs from 20 dogs with disease
Inflammation within the sac initially without
 infection but identified by palpation of sac
(either anal sac infection or anal sac
abscessation) to identify the bacterial
Anal sacculitis
flora present and their antibiogram. The
Infection and chronic change in the sac
identified on palpation and by presence
data are contained in Tables 3 and 4
 infiltrate on cytology
of an inflammatory
(see overleaf).
Anal sac infection and abscess
The bacteria found in normal anal
sacs and infected sacs are very similar,
Figure 1. Possible progression of anal sac disease.
which is why
culture results
alone should not
be used to make
a diagnosis of
anal sac disease.
Interestingly, the
profile of the anal
Table 1. Suggested reasons why anal sacs fill up. Table 2. Factors suggesting anal gland disease.
sac organisms
32
DERMATOLOGY
VETERINARY PRACTICE JANUARY 2016
and culture, to flush the sac
using an antiseptic solution
such as chlorhexidine and
triz EDTA, and then pack
it with a topical antibiotic
(Figure 4).
Although off-license use
of bovine intramammary
preparations containing
clavamox and prednisolone
is useful, the author (SP)
Table 5. Antibiotic sensitivity pattern of
would prefer to use a
Enterococcus faecalis (y axis antibiotic, x axis
product with an anti-yeast
percentage).
component.
Key to antibiotics: Fusid – fusidic acid, Poly – polymyxin,
Fram – framycetin, Gent – gentamicin, Dox – doxycycline, Pra
Ear preparations
– pradofloxacin, Orb – orbifloxacin, Enr – enrofloxacin, Mar
containing aminoglycosides – marbofloxacin, Cvn – cefovecin, Ceph- cephalexin, Amc –
clavamox, Ery – erythromycin, Clind – clindamycin.
such as framycetin
and gentamicin would
seem good first choices.
Fluoroquinolones should
be used as a second choice
antibiotic.
Where possible, the
author (SP) would choose
a preparation that is oilbased rather than propylene
glycol-based to avoid any
potential irritant reactions
Table 6. Antibiotic sensitivity pattern of Proteus
to the latter. Where anal
sacs have formed an abscess mirabilis (y axis antibiotic, x axis percentage).
and ruptured, systemic
a fluoroquinolone as a second line
antibiotics are important.
option, the data showing no significant
Useful choices in these situations,
difference between enrofloxacin,
based on Table 8, would be
marbofloxacin and pradofloxacin.
clavamox as a first line choice and
Whilst the authors are aware
smell associated with anal sac
secretions.
Whilst Enterococcus faecalis is
capable of growing at a wide
range of different temperatures,
Proteus mirabilis and E. coli
grow best at mammalian body
temperatures, the optimum
growth temperature for Proteus
Table 3. Bacteria and yeast identified from
mirabilis being slightly higher at
normal anal sacs.
40ºC than E. coli (37ºC), which
might explain why inflammation
within an infected sac may
lead to a switch in the two
populations of bacteria.
The second stage of this
study, undertaken by the
authors, was to assess antibiotic
sensitivity for a range of topical
and systemic antibiotics.
Table 4. Bacteria and yeast identified from
Although antibiotic sensitivity
infected anal sacs.
was performed for all of the
organisms identified on culture, only
from normal sacs does not mirror that
the results for the most “significant”
of either canine skin or faeces.
organisms – Enterococcus faecalis, E. coli
The most significant change in
and Proteus mirabilis – are reported in
pathogen profile between these two
Tables 5, 6, 7 and 8.
small studies is the increased numbers
Antibiotic sensitivity becomes
of Proteus mirabilis in the group of dogs
important when anal sac infections
with infection.
require therapy. Where there is anal
Proteus mirabilis (like E. coli)
sacculitis and infection within an intact
is a Gram-negative facultative
anal sac, the authors would generally
anaerobic rod-shaped bacterium.
select a topical antibiotic.
It characteristically produces a very
A suitable protocol might include,
distinct “fishy odour” which probably
after sampling the sac for cytology
accounts for a large part of the
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VETERINARY PRACTICE JANUARY 2016
antibiotics listed, notably
fuscidic acid, erythromycin
and clindamycin, and
enterococci are innately
resistant to clindamycin
and the cephalosporins,
this is not something that
clinicians are familiar with
and likely explains the very
high incidence with which
clindamcyin is prescribed in
Table 7. Antibiotic sensitivity pattern of E. coli anal sac disease.
Where disease is recurrent
(y axis antibiotic, x axis percentage).
or where palpation of the
that Gram-negative rods display
sac suggests the potential presence of
innate resistance to certain of the
neoplasia, anal sac removal is preferable.
DERMATOLOGY
33
References and further reading
James, D. J., Griffin, C. E., Polissar, N. L. and
Neradilek, M. B. (2011) Comparison of anal sac
cytological findings and behaviour in clinically
normal dogs and those with anal sac disease. Vet
Derm 22 (1): 80-87.
Lake, A. M., Scott, D. W., Miller, W. H. and Erb,
H. N. (2004) Gross and cytological characteristics
of normal canine anal sac secretions. JAVMA
51: 249-253.
Maina, E., Galzerano, M. and Noli, C. (2014)
Perianal pruritus in dogs with skin disease. Vet
Derm 25 (3): 204-208.
Pappalardo, E., Martino, P. A. and Noli, C. (2002)
Macroscopic, cytological and bacteriological
evaluation of anal sac content in normal dogs
and dogs with selected dermatological disease.
Vet Derm 13 (6): 315-322.
Robson, D. C., Burton, G. G. and Lorimer, M.
F. (2003) Cytological examination and physical
characteristics of the anal sacs in 17 clinically
normal dogs. Aust Vet Jour 81: 37-41.
Table 8. Selected systemic and topical
antibiotics with sensitivity patterns
against common anal sac pathogens
[Proteus mirabilis (PM), E. coli
(EC), Enterococcus faecalis (EF)] (y
axis antibiotic, x axis percentage).
CANINE HEPATOCUTANEOUS SYNDROME
(superficial necrolytic dermatitis, necrolytic migratory erythema, metabolic epidermal necrosis, diabetic dermatopathy)
 Hepatocutaneous syndrome is an
and perinasal areas (Figures 1 and 2)
uncommon disease in dogs and very
and mucocutaneous junctions. There
rare in cats.
is usually marked hyperkeratosis of
 The majority of
the footpads with
DAVID GRANT
cases are associated
ulceration and
continues the series of
with chronic liver
fissures (Figure
dermatology briefs
disease with a much
3). These lesions
smaller number
are painful and
being caused by a glucagon secreting
are often the trigger for requesting
pancreatic neoplasm. In a survey of
veterinary advice.
75 cases in the veterinary literature
only six were caused by a pancreatic
Differential diagnosis
neoplasm (Miller, Griffin and
(from Hnilica, 2011)
Campbell, 2013).
 Cutaneous epitheliotropic
 The pathogenesis is incompletely
lymphoma
understood. In the case of pancreatic
 Pemphigus foliaceus
neoplasia, increased gluconeogenesis
 Pemphigus vulgaris
may be caused by hyperglucagonaemia.  Systemic lupus erythematosus
With liver disease there may be
 Drug eruption
increased catabolism of amino acids.
 Pedal pyoderma with an underlying
 With both diseases the end result is
cause (dermatophytosis, demodicosis)
low plasma amino acid concentrations
 Zinc-responsive dermatosis
and depletion of epidermal protein,
which is thought to be the cause of
Diagnosis
skin lesions.
 Blood samples may reveal a nonregenerative anaemia and in the case of
Clinical features
an underlying hepatopathy there will
 Signs of ill health may be apparent
usually be an increase in serum alkaline
at initial presentation or a few months
phosphatase, alanine aminotransferase,
after the skin lesions.
total bilirubin and bile acids.
 Polydipsia.
Hyperglycaemia is also possible.
 Polyuria.
 The most useful diagnostic tests in
 Concurrent diabetes mellitus may
practice are abdominal ultrasonography
be present with the above signs.
and skin biopsy. With liver disease
 Skin lesions are variable and
there are hypoechoic regions
include crusting, erosions and ulcers
surrounded by hyperechoic areas giving
commonly occurring in the periocular
rise to a honeycomb pattern which is
very suggestive. Pancreatic neoplasia
David Grant, MBE, BVetMed,
may also be detected either in situ or as
CertSAD, FRCVS, graduated
liver metastases.
from the RVC in
 Skin biopsy, particularly if
1968 and received
performed early, is diagnostic in many
his FRCVS by
cases. There is parakeratosis, oedema
examination in 1978.
in the stratum spinosum caused by
He was hospital
vacuolated keratinocytes and a deeply
director at RSPCA
basophilic basal layer. This gives rise
Harmsworth for 25
to a “red, white and blue pattern”
years until his retirement from
sometimes called the “French flag”.
the RSPCA and is currently
 Liver biopsy will identify the type
engaged in writing and lecturing
of hepatopathy.
internationally, mainly in
 Glucagon concentrations will
veterinary dermatology.
be elevated in pancreatic neoplasia
cases but may or may
not be elevated with
hepatopathy.
 Plasma amino acid
concentrations are
markedly decreased.
Treatment
three to six raw
egg yolks per day
together with zinc
and essential fatty acid
supplementation.
 As the hepatopathy
is usually irreversible,
the prognosis is very
poor with survival time
after the onset of skin
lesions a few months
only in the majority of
cases. There is, however,
a recent report of
prolonged survival in a
dog (Bach and Glasser,
2013). This case was
managed for 24 months
with a combination
of oral fatty acid and
protein supplements,
intravenous amino acid
infusion and intravenous
lipid infusion. The
authors suggest that
the addition of lipid to
the treatment regime
was highly beneficial
and to the best of their
knowledge had been
reported previously in
the veterinary literature.
 Rarely, in the case
of a benign pancreatic
tumour such as
Figure 1. Erythematous
glucagonoma, surgical
periocular lesions with
resection of the tumour early ulceration laterally
is curative.
in a 10-year-old male
 With chronic
neutered Jack Russell
hepatic disease an
terrier.
attempt should be
made to identify an
underlying cause,
such as mycotoxins or
anticonvulsant drug
hepatotoxicity. Most
cases do not have an
identifiable underlying
Figure 2. Perinasal and
cause and in these
upper lip lesions in the
symptomatic hepatic
same dog.
supportive treatment
may prolong survival
with drugs such as
S-adenosylmethionine
(sAME) or Ursodiol.
 Parenteral amino
acid supplementation
References and
is the treatment of
suggested reading
choice for improving
Figure 3. Severe
1. Bach, J. A. and Glasser,
skin lesions in animals
pododermatitis in the
S. A. (2013) A case of
with an underlying
same dog. There is
necrolytic migratory
hepatopathy (Hnilica,
erythema managed for 24
paronychia, ulceration
2011). 10% crystalline
months with intravenous
and hyperkeratosis of
amino acid solution, or
amino acid and lipid
the pads and secondary
3% amino electrolyte
infusions. Can Vet J. 54 (9):
infection. Lesions are also
solution, both at
873-875.
visible on the pressure
a dose of 25mL/
2. Hnilica, K. A. (2011)
points of the hocks.
Hepatocutaneous
kg intravenously are
The feet were painful,
syndrome. In: Small Animal
administered over eight
which was the reason for
Dermatology. A Color Atlas
hours. This treatment
presentation.
and Therapeutic Guide, 3rd
is repeated every seven
edition, 387-385. Elsevier.
to 10 days with improvement in skin
3. Miller, W. H., Griffin, C. E. and
lesions to be expected within one to
Campbell, K. L. (2013) Necrolytic
three weeks.
Migratory Erythema. In: Muller and Kirk’s
 A less effective alternative (Hnilica,
Small Animal Dermatology, 7th edition, 540542. Elsevier.
2011) is oral supplementation with