Download Number 6 - Laboratory Animal Boards Study Group

Journal of the American Association for Laboratory Animal Science
Volume 49, Number 6, November 2010
ORIGINAL RESEARCH
Biology
Phillips et al. An Observational Assessment Method for Aging Laboratory Rats,
pp. 792-799
Primary Species: Rat
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions
SUMMARY: The authors developed a method for observational assessment to support
efficient monitoring of the health of aging rats (Brown Norway) in chemical susceptibility
studies. A 5-point scale was used to score appearance, posture, mobility, and muscle
tone (leg muscle and abdominal muscle). A score of 1 indicates no deterioration,
whereas a score of 5 indicates severe deterioration. The maximum total score (sum of
all 4 measures) was 20, with a score of 4 considered normal. Body weights were
collected weekly. Figure 2 shows a sample score sheet. Figure 3 shows photographs of
the clinical appearance of aging rats.
QUESTIONS:
1. What is a hybrid study design?
2. How do the authors define mobility?
3. What is a frequency distribution?
4. What is rank order in statistics?
5. In this study, what conclusion did the authors make about body weight
measurements?
ANSWERS:
1. A hybrid study design is a cross-sectional and longitudinal study.
2. Mobility refers to the rat’s ease of movement around the cage.
3. A frequency distribution is the empirical frequency distribution and probability
distribution.
4. Rank order in statistics in a systematized arrangement of the data values in
ascending or descending order.
5. In this study, body weight was not an accurate predictor of mortality.
Howard et al. The Pharmacokinetics of Enrofloxacin in Adult African Clawed Frogs
(Xenopus laevis), pp. 800-804
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions; T4. Treat disease or condition as appropriate; K6. Pharmacology with
emphasis on drugs used to treat spontaneous or induced disease
Secondary Species – Xenopus laevis
SUMMARY: Study investigated the pharmacokinetics and toxicity of a single
subcutaneous (SQ) or intramuscular (IM) injection of enrofloxacin (10 mg/kg) in adult,
female African clawed frogs. There were no adverse clinical signs and necropsy showed
no negative effects (i.e., liver or kidney toxicity, skin effects) of injection. The half-life,
volume of distribution and clearance were similar for both routes of administration. Peak
plasma concentrations, half-life, and AUC produced after a single dose were sufficient to
reach therapeutic levels considered effective against common aquatic pathogens and
suggest a once daily dose. Concentrations of enrofloxacin and its active metabolite were
found in the water (concentrations increased over time), so authors suggest changing
water daily to minimize drug reabsorption after excretion.
QUESTIONS:
1. What is the mechanism of action of fluoroquinolones?
a. Inhibition of DNA gyrase preventing supercoiling and synthesis of bacterial DNA.
b. Inhibition of peptidoglycan crosslinks in bacterial cell walls.
c. Binds to 50S ribosome and inhibits bacterial protein synthesis
d. Sequentially inhibit enzymes in the folic acid pathway, thereby inhibiting bacterial
thymidine synthesis
2. What is the active metabolite of enrofloxacin that was also found in the water of
these frogs?
3. The half-life of enrofloxacin in African clawed frogs is most similar to which of the
following?
a. Mammals
b. Fish
4. Why was it not possible to bioavailability of IM or SQ injection of enrofloxacin in this
study?
ANSWERS:
1. a.
2. Ciprofloxacin
3. a.
4. Bioavailability (the extent of systemic absorption) can only be measured by
comparing the IM or SQ area under the curve (AUC) with the AUC from an IV dose.
According to the authors IV dosing is not possible in X. laevis.
Papp et al. Pharmacokinetics of Cefovecin in Squirrel Monkey (Saimiri sciureus),
Rhesus Macaques (Macaca mulatta), and Cynomologus Macaques (Macaca
fascicularis), pp. 805-808
Domain 3 – Research; Task 3 -Design and conduct research
Primary Species – Macaques
Secondary Species - Squirrel monkey
SUMMARY: Cefovecin is a third-generation broad-spectrum cephalosporin antibiotic
licensed for the treatment of skin infection in dogs and cats. It is administered as a single
subcutaneous injection to those species. All published canine data indicate that the drug
is fully bioavailable after subcutaneous administration, with a mean maximum
concentration of 121 ug/L, a mean elimination half-life of 133h, and a clearance of 0.76
mL/h/kg after intravenous dosing. Cefovecin is also highly bound to plasma proteins,
96.0% to 98.7%.
Cephalosporins have well established safety and efficacy profiles. The use of an
injectable antibiotic with an extended duration of action is of great interest to zoo and
laboratory animal veterinarians. For veterinarians working with primates this type of
dosing is of benefit because it reduces the frequency of capture and restraint, decreases
the stress to animals, and lessens the risk of injuries to animal handlers. The current
dosing regimens can be difficult to administer and may contribute to treatment failure.
With these issues in mind this group set out to determine the potential use of cefovecin
in nonhuman primates by determining is pharmacokinetic parameters in several widely
used primate species.
The maximal plasma concentration of cefovecin after a single 8 mg/kg subcutaneous
injection showed only a 2-fold difference between nonhuman primates and dogs.
However, the terminal half-life was considerably shorter in nonhuman primates and
exposures were much lower in nonhuman primates than in dogs. In Cynos they
observed a high bioavailability (82%) and low distribution volume (0.16 L/kg) but
clearance was 20-fold higher than that in dogs. This was attributed to the decreased
plasma levels in nonhuman primates to an increased higher elimination rate rather than
poor absorption. In vitro liver metabolism experiments indicated that the hepatic
extraction of cefovecin is low in all 3 nonhuman primate species as previously observed
in dogs. Therefore, liver metabolism dose not play a significant role in its elimination. In
dogs, the drug is eliminated mainly (70%) by renal excretion. In Cynos the numbers
were similar, 80% of the drug was recovered in urine after IV drug dosing. The unbound
clearance in Cynos ranged from 400 to 700 mL/h/kg a value slightly higher than
estimates of glomerular filtration rate for these animals. This suggested that either renal
absorption does not occur in primates or that it is compensated by active secretion in the
proximal tubule. This finding is in contrast to the findings in dogs in which reabsorption
seems to dominate.
Cephalosporins are time-dependent antimicrobials. Successful therapy is achieved by
maintaining the effective cephalosporin concentration above 90% of the minimum
inhibitory concentration of the targeted pathogen. Protein binding is the key determinant
of the efficacy of antibacterial agents. The binding of cefovecin in primates was lower.
These results show that the drug has a much shorter plasma terminal half-life and
decreased exposure when compared to dogs. This indicates that cefovecin would have
to be dosed to primates at increased frequencies, higher doses, or both.
QUESTIONS:
1. What class of antibiotics is cefovecin?
2. What is the effective cephalosporin concentration to achieve successful therapy?
3. What species is cefovecin currently labeled for use in?
4. What is cefovecin used to treat currently?
ANSWERS:
1. Cephalosporins
2. 90% of the minimum inhibitory concentration of the targeted pathogen
3. Dogs and cats
4. Skin, soft tissue and urinary tract infections
Health Surveillance
Wilson and Hankenson. Evaluation of an Inhouse Rapid ELISA Test for Detection
of Giardia in Domestic Sheep (Ovis aries), pp. 809-813
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions; K9. diagnostic procedures - serologic, cytologic, and molecular diagnostic
tests (e.g., PCR; ELISA; IFA; HAI; MAP) and proper sampling techniques
Secondary Species: Sheep (Ovis aries)
SUMMARY: The authors of this paper attempted to find a better screening test that
would not only aid in more accurate detection of Giardia duodenalis, but also expedite
detection of true positive cases because of the zoonotic potential of this protozoal agent.
Historically, the diagnosis of giardiasis is made by microscopic visualization of feces or
intestinal tissue samples for cysts or trophozoites. These test results are most sensitive
after multiple samples are assessed within a 3-5 day interval, because of the
intermittency of cyst shedding. Furthermore, this irregular cyst excretion can cause falsenegative results and the fecal floats are time-consuming in terms of preparation and
sufficient operator experience or appropriate training.
Other methods to available for the diagnosis of giardiasis include ELISA, enzyme
immunoassays (EIA), direct fluorescence antibody assays (DFA) and PCR-based tests.
ELISA tests are appealing because they can be performed in-house rapidly (8 min) vs.
days with other testing by contract labs. A pilot study evaluating the accuracy of ELISA
testing as compared to microscopic evaluations showed a discrepancy between the
results.
Unequivocally, it was concluded that the rapid ELISA test was not a reliable method for
diagnosis of Giardia in sheep and did not confirm any single true-positive animal.
QUESTIONS:
1. A highly sensitive test is a measure of true ______ in a population.
2. A highly specific test is a measure of true _______ in a population.
3. What are the morphologic forms of giardia?
4. Do sheep usually present with clinical signs of giardia?
ANSWERS:
1. A highly sensitive test is a measure of true positives in a population.
2. A highly specific test is a measure of true negatives in a population.
3. What are the morphologic forms of giardia? Cysts and trophozoites
4. Do sheep usually present with clinical signs of giardia? Not in this case; the authors
observed any clinical signs in giardia + sheep.
Wolf et al. Generation of a Specific-Pathogen-Free Baboon Colony, pp. 814-820
Domain 1: Management of spontaneous and experimentally induced diseases and
conditions; Task 1 – Prevent spontaneous or unintended disease or condition
Domain 4: Animal care; Task 1 – develop animal husbandry program
Secondary Species: Baboon (Papio hamadryas anubis)
SUMMARY: Wild caught and conventionally raised baboons have many indigenous
viruses, bacteria and parasites. Pathologies occurring in infected animals, many of these
agents can influence the results of biomedical research using baboons. Additionally,
zoonotic agents may pose an occupational risk to caretakers and research staff.
Retro viruses and herpesviruses are of concern due to their ability to influence the
immune system and persist in the host after the initial infection event. Reactivation of
latent herpesviruses is an important problem in immunosupressed subjects and several
herpesviruses encode genes for proteins that directly affect the host immune response.
Retroviruses are important for their zoonotic potential and ability to alter immune
responses. SRV (Simian retrovirus type D) and SIV both cause immunosuppressive
effects in infected subjects. (STLV) simian T-lymphotrophic virus is associated with
lymphoma in baboons. SFV (simian foamy virus) causes reactivation and destruction of
ex vivo cell cultures. SV40, SRV or SVF have been implicated for their zoonotic disease
potential as evidenced in primate handlers. The objective of this study was to establish a
SPF colony of baboons free of 12 target viruses: 5 herpes viruses, 4 retroviruses, SV40,
measles and monkeypox.
Baboons typically deliver between dusk and dawn. Neonates were removed from their
dams as soon as possible on the morning after birth. Dams were separated from the
colony, put in a squeeze cage, injected with 10 mg/kg of ketamine and pups removed.
Care was taken not to remove successive infants from female baboons. Approximately
20 to 30 infants were recruited into the program each year. Such Infant baboons
removed from the dam within 24 hours of birth were nursery reared. Strict barrier
principles were in place to prevent disease transmission from conventional baboons
housed in the same building.
Newly arrived neonates were warm bath and allowed to air dry after a quick dip in
chlorhexidine. Infants were individually housed during the first 2 weeks. Cages were
fitted with a hanging surrogate and bottle holder. Infants were fed infant formula (Similac
Advance, Abbot) at concentrations recommended for human infants. At 3 months of age
infants were group housed in larger cages. Animals were fed commercial chow at 3
months. At 1 year of age, baboons were placed in large aluminum and concrete gang
cages and provided with food enrichment in addition to commercial chow.
Viruses were tested for using serology and PCR. Serologic testing by ELISA was used
for all herpesviruses. Samples testing positive during serologic screening were
confirmed using western blot. Animals were tested for viruses at 3, 4, 6, 9 and 12
months of age. Animal losses were due to animals testing positive for BaCMV (baboon
cytomaegalovirus) and HVP1 (herpersvirus papio 1).
Abnormal clinging behavior in young animals was observed as an abnormal behavioral
trait. Species specific grooming behavior was observed more frequently when compared
to conventional animals.
During the initial 7 years of the SPF program 171 infants were enrolled of which 76
(44.4%) animals removed from the program. Of those removed, 54 were culled due to
breaks in virus-free status, 12 died of various causes, 4 due to seizures and 6 were
removed for other reasons.
QUESTIONS:
1. An effective for development of a baboon colony free of multiple viruses consists of;
a. Early removal of infants from dams
b. Housing in small peer groups
c. Frequent virus testing
d. Aggressive culling of virus-positive animals
e. All of the above
2. The gastrointestinal parasites; Trichuris trichuria, Strongyloides stercoralis and
Strongyloides fulleborni have been included recently in the list of agents targeted for
exclusion in SPF baboon program in this facility. True or False?
3. Treatment of baboons with fenbendazole or fenbendazole-containing primate diet
can eliminate Trichuris from single- and group-housed baboons. True or False?
ANSWERS:
1. e
2. True
3. True
Experimental Use
Gadad et al. Effect of Fenbendazole on Three Behavioral Tests in Male C57BL/6N
Mice, pp. 821-825
Domain 1, Task 2: Management of spontaneous and experimentally induced diseases
and condition, Control spontaneous or unintended disease or condition
Primary Species: Mouse
SUMMARY: Authors compared the behavior of control mice (fed regular diet) with 3
groups of mice treated with dietary fenbendazole. Forty-eight male C57BL/6N mice were
randomly assigned to 1 of the 4 dietary groups. Treatment groups were (1) 4 weeks of
fenbendazole (FF), (2) 2wks of fenbendazole followed by 2wks of regular diet (FR), and
(3) 2wks of regular diet followed by 2wks fenbendazole (RF). At the end of dietary
treatment, mice were tested sequentially in 3 behavioral tests and then euthanized with
carbon dioxide. All groups underwent the following tests: (1) spontaneous activity in the
open field as a standardized measure of motor function, (2) rotarod testing as a test of
motor coordination and balance, and (3) elevated plus maze as a test of anxiety.
Results: Fenbendazole had no significant effects on horizontal or vertical activities (open
field test) or on exploratory behavior (elevated plus maze test). Fenbendazole did have a
significant effect on time spent on the rotarod. Mice in all treatment groups were
significantly heavier than were controls at day 15, and the RF and FR groups were
significantly heavier than controls at day 30. All hematologic and clinical chemistry
values were within normal limits for all groups.
QUESTIONS:
1. What are the two primary pinworms of concern in laboratory mice?
2. What type of drug is fenbendazole?
3. How does fenbendazole work to eliminate pinworms?
ANSWERS:
1. Aspicularis tetraptera, Syphacia muris
2. Benzimidazole derivative
3. Absorbed from the GI tract and metabolized in the liver to its active form. The drug is
a microtubule polymerization inhibitor and binds to the structural protein beta tubulin.
Gruda et al. A System for Implanting Laboratory Mice with Light-Activated
Microtransponders, pp. 826-831
Domain 4: Animal Care; Task - Animal Identification Systems
Primary Species – Mouse
SUMMARY: For animal welfare and economic reasons, mice are commonly socially
housed in a laboratory setting. This management practice makes identification of
individual animals challenging. Examples of identification methods currently utilized
include: ear tagging, tattooing, ear notching, and toe clipping. Although all methods
mentioned are effective, each has its strengths and weaknesses. For example, ear
tagging is quick, simple, and cost-effective; however, ear tags may be irritating to the
mouse, and often are torn from the ear or fall out if placed incorrectly. Ear notching and
toe clipping are also quick, simple, and cost-effective, but there is a limitation to the
combinations of identifying numbers which can be produced. Tattooing is a more
expensive and labor intensive form of identification which requires some training to
perform effectively. In this article, the authors describe a novel microtransponder which
can be simply placed subcutaneously in either the ear or tail of mice, including
pigmented animals. The microtransponder measures 600 x 600 x 100 um, and requires
a microtransponder injector with a 21 g flattened needle for placement. Placement in the
ear requires anesthesia and takes longer than placement in the tail, which can be done
using a mouse restrainer. Reading the microtransponder when placed in the tail is
easier and less time consuming than reading it when placed in the ear, due to folding of
the ear during "scruff" restraint. There does not seem to be biocompatibility issues with
the microtransponder for the duration of this study (6 months), but studies are ongoing.
QUESTIONS:
1. Which is not a feature of a light-activated microtransponder?
a. Its small size makes it easy to place
b. It is relatively inexpensive
c. There is minimum training involved for placement and reading of the
microtransponder
d. Placement requires anesthesia
2. What was the success rate of the microtransponder over the course of the study (6
months)?
a. 90%
b. 75%
c. 98%
ANSWERS:
1. d
2. c
Keen et al. Efficacy of Soaking in 70% Isopropyl Alcohol on Aerobic Bacterial
Decontamination of Surgical Instruments and Gloves for Serial Mouse
Laparotomies, pp. 832-837
Domain 3: Research; Task 3.11 – Aseptic requirements for performing surgery
Primary Species: Mouse
SUMMARY: Serial rodent surgeries are commonplace in biomedical research facilities,
and my present challenges to maintaining aseptic technique with each animal in the
series. This study examined using 70% isopropyl alcohol as a decontaminant for the
surgical instruments and gloves between up to 10 mouse laparotomy procedures.
Aerobic culture was performed on the instruments and gloves prior to and following each
procedure to determine bacterial contamination. Following each post-surgical culture,
the surgical instruments and the fingertips of the surgical gloves were submersed in 70%
isopropyl alcohol for 2 minutes, and for 30 seconds, respectively. Pre-surgical cultures
were obtained from the scissors, forceps, and gloves following the alcohol soak and prior
to beginning surgery on the next animal in the series. The researchers report that the
modified aseptic technique using 70% isopropyl alcohol was able to prevent bacterial
contamination in serial laparotomies of up to 5 mice.
QUESTIONS:
1. Which properties, if any, of 70% isopropyl alcohol make it useful for disinfection in
serial rodent surgeries?
a. Rapidly bactericidal
b. Does not leave a residue
c. All of the above
d. None of the above
2. 70% isopropyl alcohol was able to prevent contamination in serial laparotomies of up
to how many mice?
a. 2
b. 5
c. 10
3. What was the contact time used for the 70% isopropyl alcohol on surgical
instruments?
a. 30 seconds
b. 1 minute
c. 1 minute 30 seconds
d. 2 minutes
ANSWERS:
1. C
2. B
3. D
Hu et al. Ligation of Left Circumflex Coronary Artery with Subsequent MRI and
Histopathology in Rabbits, pp. 838-844
Domain 3: Research K3: Animal models (spontaneous and induced)
Primary Species: Rabbit
SUMMARY: Animal models of atherosclerosis using coronary artery ligation are
common; however articles describing the detail of the surgical approach and procedure
are rare for the rabbit. The current study provides a thorough description of anesthesia
preparation, induction, maintenance, and surgical procedure for ligation of the left
circumflex coronary artery in New Zealand White rabbits. The authors used 13 male
rabbits between 2.5-3.0 kg, and experienced 0 mortality. They collected data which
included ECG’s pre and post-ligation, MRI at 30 days post-ligation, followed immediately
by euthanasia and histology of the heart tissue using Harris hematoxylin stain, and
Masson Trichrome staining to differentiate between collagen and muscle fibers.
Procedures for the induction of the model were described in exceeding detail, however
post-operative care was not discussed. Analgesia consisted of a fentanyl patch. Based
on MRI findings, they determined that this model was highly reproducible for regions of
infarct. Some basic aspects of cardiac physiology and practical considerations in the
procedures to reproduce the model are within the discussion section. They also discuss
the benefits of Masson trichrome staining, and rabbits as models of cardiovascular
research.
QUESTIONS:
1. In a rabbit model of coronary artery disease, which coronary vessel is the main
arterial supply to the left ventricle?
2. In Masson trichrome staining of the heart, how is trichrome staining applied?
3. In non-intubated rabbits, what device can be used in lieu of an endotracheal tube to
provide positive pressure ventilation in the case of sudden apnea?
ANSWERS:
1. Left circumflex coronary artery
2. Immersion of sections into Weigert iron hematoxylin followed by Biebrich scarlet-acid
fuchsin, phosphomolybdic-phosphotungstic acid, and aniline blue
3. Aspirator (laryngeal airway) mask
Weaver et al. A Model of Clinical Evaluation of Perioperative Analgesia in Rabbits
(Oryctolagus cunniculus), pp. 845-851
Primary Species: Rabbit
SUMMARY: This article describes surgical ovariohysterectomy and telemeter placement
in 20 female rabbits. Rabbits were assigned to 4 treatment groups: buprenorphine at
0.02mg/kg SQ every 12 hours for 3 days; fentanyl (25mcg patch placed 24hrs
preoperatively); ketoprofen (1mg/kg SQ every 24 hours for 3 days); and control (no
treatment given). Various physiologic and behavior variables were recorded by blinded
observers, including food and water consumption, fecal output, and remotely recorded
behaviors during daily exercise in large floor pens. Compared with preoperative values,
significant declines occurred in: food consumption, water consumption, fecal output,
mean travel distance and rearing. No single treatment proved significantly better than
another, including the control.
The authors provided significant discussion on lack of improvement with treatment. One
major limitation was the lack of a known effective analgesic regimen. Other explanations
may include inappropriate dosing frequencies, ineffective choices of analgesics, and the
inability of the method of assessment to detect differences. The authors concluded with
stating that food and water intake, activity and fecal output may be useful variables in
assessing analgesic efficacy, and indicate more work needed in this area.
QUESTIONS:
1. T/F. Animals within the opioid treatment groups of this study showed no difference in
fecal output, going against the widely claimed dogma that opioids reduce propulsive
motility of the GI tract.
2. T/F. Of the many behavioral variables monitored, the two that appeared to be most
affected by surgery were travel distance and rearing.
3. T/F. Mean body weight returned to normal by 7 days post op.
ANSWERS:
1. T
2. T
3. F
Shousha et al. Comparison of Electrocardiographic Recordings in Open-Chest
and Close-Chest Swine Models, pp. 852-855
Primary Species: Swine Sus scrofa
Domain 3: Research
SUMMARY: The hypothesis is that a thoracotomy in swine would affect the ST segment,
even in the absence of a procedure that would induce myocardial ischemia because the
standards for assessment and interpretation of electrocardiography are based on the
conventional noninvasive model.
Cardiac electrical activity is influenced by the autonomic nervous system and other
biochemical conditions, which can fluctuate during surgery. Eight healthy male Landrace
swine were studied. Seven electrodes were positioned on the chest, back, and limbs of
the swine for continuous recording of 3 bipolar pseudo-orthogonal electrocardiographic
leads throughout the experiment. First a vascular procedure was performed and data
was collected to compare to the thoracotomy procedure. The heart rate did not
significantly differ between the vascular procedure and the thoracotomy. In all swine, a
statistically significant ST-segment depression was seen after the thoracotomy. This
depression was not seen with baseline readings or after the vascular procedure. In
conclusion, invasive surgical interventions could interfere with the electrocardiographic
interpretation of myocardial ischemia in thoracotomized animal models, because
thoracotomy procedure in acute open-chest swine models generates significant STsegment changes on the electrocardiogram. The physiologic mechanism of these
changes is not fully understood.
QUESTIONS:
1. Why is it important that the thoracotomy affected the ST segment?
2. True/False: All surgery changes the ST segment.
ANSWERS:
1. It could interfere with the electrocardiographic interpretation of myocardial ischemia.
2. False.
CASE REPORTS
Adissu and Turner. Insulinoma and Squamous Cell Carcinoma with Peripheral
Polyneuropathy in an Aged Sprague-Dawley Rat, pp. 856-859
Domain 1; Task 3 - Diagnose disease or condition
Primary Species: Rat
SUMMARY: A 3-year old male Sprague-Dawley rat presented with anorexia, polyuria,
polydipsia, weight loss, paresis, and proprioceptive deficits of the hind limbs. Serum
glucose was within normal limits. Necropsy revealed a solitary, well-demarcated, pale,
tan to white, firm, 0.8 cm diameter nodule protruding from the mid-duodenal pancreases.
The histologic and immunohistochemical features were consistent with beta-cell
adenoma (insulinoma). Also noticed during necropsy were two large irregular oral ulcers
associated with invasive metastatic epithelial cells. Finally, there was evidence of
peripheral neuropathy in the sciatic and brachial nerves with degeneration and atrophy
of the associated muscles.
Beta-cell adenoma is the most common islet cell tumor in the rat and is characterized by
encapsulation, expansile growth, and absence of invasion or metastasis. Metastatic islet
cell carcinoma is rarely described in rats. Small adenomas must be distinguished from
islet hyperplasia which is a common age-related change. Immunohistochemical labeling
for insulin in an adenoma is positive throughout the cells of the tumor while the staining
in the rest of the pancreas is largely centralized within the islets. Immunohistochemistry
for glucagon in adenomas tends to show a random distribution of stained cells while
hyperplastic lesions show staining in a zone around the perimeter of the islet. Other
age-related changes seen in this case include acinar fibrosis, ductal hyperplasia, and
interstitial lymphocytic infiltrates.
Microangiopathic changes in the endoneurium of the peripheral nerves have been
previously reported in rats with insulinomas. These changes are known to occur even in
the absence of hypoglycemia.
Spontaneous oral squamous cell carcinomas are rare in rats. The extensive local
invasion in the absence of metastasis to lymph nodes seen here is similar to canine
nontonsillar oral squamous cell carcinoma.
QUESTIONS:
1. T/F: Insulinomas in a rat will always present with a fasting hypoglycemia.
2. Which of the following histological characteristics are NOT typical for beta-cell
adenomas?
a. Expansile growth without invasion or metastasis
b. Glucagon-staining at the periphery of the pancreatic islets
c. Surrounded by a thin, fibrous capsule
d. Insulin-staining in a majority of the cells throughout the tumor.
3. T/F: Insulinoma should be a differential for rats with clinical signs suggestive of
primary disease of the nervous system.
ANSWERS:
1. F. Definitive diagnosis is by histology and immunohistochemical staining.
2. B. Cells positive for glucagon will typically be scattered throughout the tumor.
3. T. Even in the absence of hypoglycemia.
Kolappaswamy et al. Recurrent Idiopathic Gingival Enlargement in an Olive
Baboon (Papio anubis), pp. 860-862
Secondary Species – Olive Baboon (Papio anubis)
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions; T4: Treat disease or condition as appropriate; K5: anatomic pathology
including pathogenesis of significant naturally occurring (e.g. tuberculosis) and
experimentally induced (e.g. collagen-induced arthritis) diseases; typical gross and
histopathologic lesions (e.g. age-related changes, or pathologic changes of adverse
phenotypes associated with genetically modified rodents); and pertinent anatomic
pathology techniques (e.g. Steiner's stain)
SUMMARY: Gingival enlargement has been well described and is considered to be of a
multifactorial etiology in humans, however case reports in nonhuman primates are rare.
The oral anatomy and radiography of baboons is similar to that of humans, as the
presence of plaque, calculus and subgingival pocketing.
Case Report: 14 y.o. male, unmanipulated baboon presented for difficult in labial
closure. A history of mild gingival enlargement previously treated by gingivectomy (2 yrs
prior). No significant physical exam findings except proliferative gingival tissue
precluding the ability to close the upper lip over incisors and canine teeth. No
abnormalities in behavior, eating, etc. noted. Radiographs were unremarkable and no
gingival enlargement noted in the premolar or molar area.
Surgical excision: Excessive gingival tissue was resected to approximate normal
margins. Histopathology consistent with gingival overgrowth - dense collagenous
connective tissue fibrosis expanding and elevating submucosa. No evidence of
neoplasia or infection.
Healing noted within 4 weeks post-operatively.
Further studies should be directed to the specific etiologies of recurrent gingival
enlargement. Age, host response and the chronic exposure to dental plaque and
calculus, as in dogs and humans, cannot be ruled out as cause.
QUESTIONS:
1. What is the dental formula of Papio spp.?
2. The etiology of gingival enlargement (hyperplasia) of humans has been documented
from what sources?
a. Age
b. Drug induced (cyclosporine, erythromycin, calcium channel blockers)
c. Plaque
d. All of the above
ANSWERS:
1. 2/2, 1/1, 2/2, 3/3 = 32
2. D
Hopper et al. Camptomelia in a Rhesus Macaque (Macaca mulatta), pp. 863-867
Task 1 K1, K5, K8
Primary Species - Macaca mulatta
SUMMARY: This was a case report on an 8.5mo-old female rhesus macaque that was
reported to the vet staff with a lump on the right arm below the elbow. The lump turned
out to be an actual anatomical abnormality with the arm and the bone. The condition
turned out to be idiopathic camptomelia, or bowing of the long bones. This condition is
very rare, and is an osteochondrodysplasia characterized by skeletal malformations. In
humans, this can also lead to nonskeletal malformations, sex reversal, and mortality.
Some key differential diagnoses for this case of bending of the long bones were rickets,
primary-, secondary-, and pseudo-hyperparathyroidism, skeletal fluorosis, and genetic
developmental dysplasias (such as camptomelia). To rule these out, vitamin D levels
were measured (low in rickets) and radiographs were taken (characteristic changes in
rickets were not seen). Parathyroid hormone levels were measured and were normal,
there were no signs of renal disease physically or with blood work (cause of 2ndary
hyperparathyroidism), and none of the typical causes of pseudo-hyperparathyroidism
were present (tumor). The fluoride level in the water was normal and normal radiographs
along with normal circulating calcium and vitamin D levels ruled out fluorosis. Bone
density was also normal. The diagnosis of camptomelia was based on exclusion of all
other possibilities. 8 months later, the macaque had no further abnormalities develop,
and 2 siblings were both normal. The cause of this condition is not known.
QUESTIONS:
1. What is camptomelia?
2. What are some differential diagnoses for bending of the long bones?
ANSWERS:
1. A bending of the limbs that produces a permanent curving or bowing often congenital
in origin.
2. Rickets, hyperparathyroidism, fluorosis, and genetic disease. Test vitamin D levels,
renal function, radiographs, calcium levels, and bone density.
Alves et al. Giant Thoracic Schwannoma in a Rhesus Macaque (Macaca mulatta),
pp. 868-872
Domain 1 - Management of Spontaneously and Experimentally Induced Diseases and
Conditions, T3 - Diagnose disease or condition as appropriate; Domain 2 - Management
of Pain and Distress, T3 - Euthanatize (Euthanize)
Primary Species - Macaca mulatta
SUMMARY: This is the first documented case of thoracic schwannoma in a rhesus
macaque and the second reported case of schwannoma in a non-human primate. A
schwannoma is a benign peripheral nerve sheath tumor that occurs in about 90% of
humans with neurofibromatosis type 2. Most patients with mediastinal schwannomas are
asymptomatic. These tumors have also been described in dogs and cattle, among other
species. In this case report, a 15-year-old male rhesus macaque was presented for
physical examination after a confrontation with another macaque in the colony, resulting
in severe facial wounds. He was dyspneic on presentation, which was attributed to
trauma and hemorrhage, and the wounds were cleaned and closed. The animal grew
progressively dyspneic post-operatively and was anesthetized for physical examination
and thoracic radiography. Radiographs revealed a cranial mediastinal mass, and an
exploratory thoracotomy was performed. An 8- to 10-cm firm, well-circumscribed
mediastinal mass compressing the lungs was found, and the animal was euthanized due
to poor prognosis. On necropsy, a smaller (2 cm), similar tumor was noted on the right
body wall. Histopathology of the masses revealed a lobulated architecture with a fibrous
capsule, spindle cells with indistinct cell borders, 1-10 mitotic figures per high power
field, palisading nuclei, and central areas of hemorrhage, necrosis, and mineralization.
The tumor cells stained positive for S100 protein, vimentin, glial fibrillary acidic protein,
nerve growth factor receptor protein, laminin, and collagen IV, consistent with tumors of
peripheral nerve sheath origin. The histology, immunohistochemical data, physical
examination, and history are all consistent with those of schwannomas in humans. Due
to the relative infrequency of this tumor type in non-human primates, detailed etiological,
therapeutic, and prognostic data are not available.
QUESTIONS:
1. Most human patients with mediastinal schwannomas are asymptomatic for the
tumors.
A. True
B. False
2. Which of the following immunohistochemical markers ARE NOT found in peripheral
nerve sheath tumors?
A. S100 protein
B. Vimentin
C. Glial fibrillary acidic protein
D. Nerve growth factor receptor protein
E. None; that is, all of the above are found in peripheral nerve sheath tumors
3. Schwannomas are common and well-documented in non-human primates.
A. True
B. False
ANSWERS:
1. A
2. E
3. B
Han and Capuanno. Successful Treatment of Cryptosporidiosis in 2 Common
Marmosets (Callithrix jacchus) by Using Paromomycin, pp. 873-875
Domain 1
Secondary Species: Marmoset/Tamarins (Callitrichidae)
SUMMARY: Cryptosporidia are intracellular extracytoplasmic organisms with life cycles
similar to those of many apicomplexan protozoan parasites. However, cryptosporidia are
unique in that they alter the enterocyte membrane to create a niche for themselves
between the cell membrane and cytoplasm. Cryptosporidiosis is considered to be a selflimiting disease in immunocompetent human patients, nursery-reared infant macaques
(Macaca mulatta), and other animals. Cryptosporidiosis may be asymptomatic in
marmosets (Callithrix jacchus) but has been reported to cause enterocolitis in
immunocompetent marmosets, for which supportive therapy is the only published
treatment.
Paromomycin is an aminoglycocide antibiotic that has been one of the most widely used
agents to treat cryptosporidiosis in immunosuppressed human patients. The drug has
shown efficacy in experimentally infected animal models, for prophylaxis in outbreaks of
ruminants, and in cats with clinical cryptosporidiosis, although paromomycin toxicity in
cats has been reported.
In this article, two pair-housed marmosets arrived from a quarantine facility in good
condition. One week after arrival, both marmosets were reported to have loose feces
mixed with fresh blood and mucus. Fecal samples were ELISA-positive for C. parvum.
The marmosets had been noted as having diarrhea and low body weight on arrival into
quarantine. Treatment with paromomycin began 2 wk after the first episode of loose,
bloody feces was observed. Treatment dose and agent were based on the human
literature and consisted of paromomycin (15 mg/kg PO) twice daily, initially for 2 wk.
However, feces remained loose on day 14 of treatment and the authors added 2 weeks
to the treatment period. No additional loose feces were noted after completion of the full
28-d treatment, and both marmosets gained weight during the treatment period. Fecal
samples collected and submitted for cryptosporidium ELISA at the end of the treatment
period and 2 additional times, 2 wk apart, all were negative.
QUESTIONS:
1. How many days of treatment are needed to abolish clinical signs associated with
Cryptosporidiosis in marmosets?
a. 14
b. 21
c. 7
d. 10
e. 28
2. What is the antibiotic of choice to treat Cryptosporidiosis in marmosets?
a. Amoxicilin
b. Paromomycin
c. Gentamicin
d. Engemycin
e. Ciprofloxacin
3. What is the treatment dose used for treating Cryptosporidiosis in marmosets?
a. 250 mg/kg
b. 500 mg/kg
c. 150 mg/kg
d. 15 mg/kg
e. 25 mg/kg
ANSWERS:
1. e. 28
2. b. Paromomycin
3. d. 15 mg/kg