Contemporary Topics
Volume 42(6)
Refinements in the care and use of animals in toxicology studies regulation, validation, and progress pp. 8-15
This paper provides an overview of issues surrounding implementation of animal care refinements in toxicology laboratory settings, including regulatory constrains, conducting validation studies, current progress in refinements, and areas for future consideration. There has been strong interest in extending refinements and advances in animal care and use to animals used in regulated toxicology studies. Regulatory Oversight of Toxicology StudiesToxicology studies often have a direct effect on human health and are highly regulated by government agencies. Good Laboratory Practice (GLP) regulations were introduced to ensure study reliability and to enhance the overall quality of safe studies. Responsibility for study conduct, documentation, analysis, and reporting rests with the Study Director, and this person represents the single point of study control (GLP 58.33). Management is responsible for overseeing facility standards, organization, and the resources necessary to conduct the study appropriately (GLP 58.31). Toxicology facilities must comply with the animal care and use requirements of the USDA. Those facilities conducting work for the United States Government must also comply with US Public Health Service (PHS) regulations. Many facilities are accredited by AAALAC. To meet animal welfare and GLP requirements, enrichment programs for colony and study animals must be detailed in Standard Operating Procedures (SOPs) or IACUC-approved policies and are often managed by enrichment coordinators with specialized training or background in animal behavior. While it is usually not difficult to incorporate refinements and enrichments for colony animals, it is often difficult to do so for study animals without clear evidence that the impact of the refinement on study outcome will be negligible. Validation of Refinements in Animal Care and Use in Toxicology Validation is the process by which reliability and relevance of a Particular refinement is assessed. Reliability refers to the reproducibility of baseline results and the lack of interference with the toxicology study. Relevance refers to establishing the scientific meaningfulness and usefulness of a refinement. Validation studies require careful planning and should include collaboration and support of Toxicology Management and Study Directors. After the study, the results should be analyzed to assess reliability and relevance to the study objectives. The information should be shared with Toxicology Management and Study Directors to encourage support for the change, and facility SOPs should be developed or modified to incorporate the change. Acceptance by Toxicology Management and Study Directors of the results and the ethical imperative to change can only be accomplished through frequent dialogue between all parties, in concert with the IACUC, and prompt dissemination of results. Progress in Animal Refinement and Enrichment in ToxicologyBest practice guidelines for industry have included further suggestions for refining animal care during studies, such as opportunities for social contact, housing, enrichment opportunities, and human interaction. Recently presented validated refinements include chew toys and nestlets for rodents, environmental enrichment programs for short-term housing of macaques, pair or group housing of study dogs, pair housing of cynomolgus and rhesus macaques on study, pair housing of study rats in solid-bottom cages. Areas for Future Refinement of Animal Use in Toxicology Studies much can be done to continue refinement of animal care and use in Toxicology research. More consistent promotion of social housing for all species on chronic studies is a refinement that would have a major positive impact on animal well-being in toxicology studies. Another potential area for refinement that requires further validation is determination of toxicology study endpoints. Specific endpoints should be adopted that differentiate between direct pharmacologic or toxicologic effects and those occurring secondarily. Biomarker panels for study endpoint determination might be developed using similar biochemical or molecular screening assays to monitor early DNA damage, changes in mRNA and protein levels, cytokine release, and cellular toxicity in vivo using readily available samples. Less consideration is given to veterinary nursing support of rodents when their clinical condition deteriorates. A number of treatment options exist (e.g., cageside monitoring of electrolytes, fluid therapy, food treats), which could be used to increase animal comfort and the scientific quality of results. Continuing to explore and develop alternative dosing and restraint systems for study animals is an important area of refinement. Mixing test substances with readily consumed, palatable ingredients would permit cageside dosing. This practice would significantly reduce animal stress. The use of miniaturized and minimally invasive monitoring equipment to increase the information gained from each animal and detect alterations in animal condition is another area of potential refinement in animal use that requires validation. Implementing consistent training of laboratory animals is a final area of consideration for refinement. Best-practice guidelines have been developed by industry to refine the Are and use of animals in toxicology studies and validation studies exist for several of those proposed changes. Open discussion must continue to encourage changes in practices during regulated studies. Question:There are legislated requirements for safety testing of pharmaceutical and other products intended for human application or consumption. Who is responsible for administering and enforce these regulations in the United States? Answer:
The Food and Drug Administration (FDA)
Assessing the risk of transmission of three infectious agents among mice housed in a negatively pressurized caging system pp. 16-21
Description: It has been shown that ventilated cages run at negative pressure in a mouse room greatly reduced the exposure of animal care personnel to the major mouse allergen (Mus m 1). This study was designed to see if a similarly pressurized ventilated caging system would affect the risk of spread of infectious agents between cages or mouse racks. Mice (tumor necrosis deficient B6, TNF) persistently infected with the following agents: P. carinii (aerosol transmission), H. bilis (Fecal oral transmission), and P. pneumotropica (venereal, fecal oral transmission) were housed in a room with naļve SCID mice (8-10 weeks old) for a period of 12 weeks (Experiment 1). Naļve animals were exposed to the infected animals by direct contact, by placing SCID mice on dirty bedding for the cages of infected animals, or by handling the uninfected mice after handling the infected TNF mice. In addition to this study a 12-month study (Experiment 2) was also conducted to examine transmission between breeding colonies of the animals infected with the three agents and uninfected SCID mice like those used in the previous experiment. The agents were detected in both experiments by PCR (fecal swabs or cecal swabs for H. bilis. Oropharyngeal, tracheal or vaginal swabs for P. pneumotropica). Histopathology (Gomori silver stain) and PCR were used as detection methods for P. carinii. All cage changes were conducted within a negatively pressured change station. Mice were transferred by forceps (except those being exposed by handling) dipped in Wescodyne solution (broad spectrum iodophore) during cage changes.
Results:
Experiment 1
Cohabitation- In experiment 1, P. carinii was transmitted to animals that were cohabitated. The agent was identified as early as 4 weeks into the experiment by PCR. Histopathology conducted on week 12 confirmed the infection in the cohabitated population (20 of 20 cages at both 8 and 12 week time points). H. bilis was identified at every sampling period by PCR amplification of fecal samples. Detection was intermittent, but was corroborated by cecal PCR conducted on week 12. P. pneumotropica was identified by PCR at every sampling period, but its incidence was also intermittent.
Soiled Bedding- Experiment 1. Weekly transfer of soiled bedding did not result in the identification of P. carinii until the 12-week sampling period (4 of 20 cages). Mice were positive by both PCR and histopathology. Only 1 mouse was PCR positive for H. bilis during the 3 sampling periods. Mice were positive from 12 of 20 cages on week 10. It was interesting to note that the one mouse that was PCR positive on week 6 was negative on week 10 and 12. Transmission of P. pneumotropica occurred in only 1 of 20 cages during the first three sampling periods, in two cages in weeks 8 and 10, and in 8 cages on week 12.
Handling- No transmission of any of the agents occurred by handling naļve SCID mice after handling triply infected TNF mice.
Experiment 2.
This was a 12-month study of transmission of the three agents used in experiment one under the same conditions (negative pressure cage racks). None of the SCID mice tested became infected with H. bilis or P. pneumotropica at 3,6,9 or 12-month time points. P. carinii was detected in the lungs of 7 of 96 mice on the 12-month time point only. No cages tested at the 3,6,or 9-month time points were positive for P. carinii. Three cages contained only SCID mice that were on the rack directly in front of the exhaust of the changing station. The other four were on the other side of that rack and was composed of TNF and SCID mice that were randomly placed. All the mice positive for P. carinii by PCR had their lungs examined histologically using both H and E and silver staining, and the histology confirmed the PCR results.
High Risk practices:
P. Carinii was readily spread to immunocompromised SCID mice by direct contact with 30% infected by 4 weeks and 100% by week 8. TNF mice born to P. carinii infected parents were negative at ages of 24 and 37 days, but were uniformly positive by 60 days. Previous reports indicated this was due to the low level of cysts in the lung at earlier ages were not detectable until day 25.
There was a discernable decrease in the efficiency of transmitting P. carinii by soiled bedding as compared to direct cage contact. The first discernable transmission occurred by week 8 and only 20 % of the cages were involved. This may indicate that the detection of P. carinii by using dirty bedding sentinels maybe less than ideal if the number of donor cages housing infected mice was small.
No transmission by handling was detected. This suggested that fomites are may not readily transmit P. carinii infection at least during periods of short handling. The absence of infection of the SCID mouse controls and the confirmed infection in the TNF controls confirm that the spread of P. carinii can be suppressed by negative cage within pressure combined with the use of filter tops and a ventilated changing station.
Transmission studies of H. bilis and P. pneumotropica by direct contact and soiled bedding was similar to findings from previous work. Soiled bedding was not an effective method of transmitting infections by these agents.
Handling did not result in
detectable transmission for these agents. The absence of infection in the
uninfected control groups suggests that these organisms are not readily
transmitted by aerosol in cages with negative intracage pressure combined with
filter tops and a ventilated changing station.
Questions:
Answers:
Recovery of male rats from major abdominal surgery after treatment with various analgesics pp. 22-27
The objective of the study was to compare the recovery of male Sprague-Dawley rats after implantation of a telemetry device into the abdominal cavity when treated post operatively with and buprenorphine (0.12 mg/kg), butorphanol (4.0 mg/kg), or ketoprofen (16 mg/kg) and 5% dextrose, or with 10 ml of 5% dextrose only. (All animals regardless of whether they received an analgesic or not received the 5% dextrose solution post op) The only analgesic administered more than once was butorphanol with was given at 4, 12, and 20 hours post op. The numbers of animals in each group was not indicated. The parameters used to access recovery were heart rate, mean arterial pressure, home cage activity, body weight, and food and water consumption. The telemetry information was sampled for 10 seconds every 5 minutes.
Heart rate, nocturnal home cage activity water consumption and body weight indicated the animals recovered by 7 days post op. The amount of home cage activity during the dark phase is a good indication of the amount of pain and distress being experienced by the rat. Food consumption returned to normal 5 to 12 days post op depending on the analgesic administered. Buprenorphine treated animals recovered more slowly on the basis of nocturnal activity, Heart rate, and food and water intake. When compared to groups receiving only subcutaneous fluids, buprenorphine and butorphanol delayed recovery, where ketoprofen did not retard or advance the recovery rate.
Rats that were given butorphanol had a significantly increased heart rate only on the day after surgery. They also had elevated mean arterial pressure on the first 2 days post op. Butorphanol has been shown to decrease anti-diuretic hormone levels in rats leading to diuresis which could lead to dehydration. The study results indicate that butorphanol actually delayed recovery relative to rats given only subcutaneous fluids.
Rats given Buprenorphine have been shown to have an increase in consumption of non-food items (pica) such as bedding. The study results indicate buprenorphine also delayed post surgical recovery relative to rats given only subcutaneous fluids.
Using Heart rate and nocturnal activity measures the authors conclude that post op recovery was complete by days 7-11 which agrees with food and water consumption and body weight gain.
Water consumption returned to normal presurgical levels much sooner than did food intake, but the normalization of water intake was delayed by 2 days in buprenorphine treated rats. Butorphanol and ketoprofen had no effect on return to water consumption when compared to animals who received no analgesia.
Questions:
1. Return to normal with concern to heart rate following abdominal surgery in male rats was reported to occur when?
2. Post operative return to normal for water consumption occurs:
3. Which analgesic results in increased anti-diuretic hormone levels?
Answers:
1=d, 2=a, 3=d
Maintaining patency and asepsis of vascular access ports in Yucatan miniature swine pp. 28-32
A disadvantage of swine as an animal model is their lack of easy
accessible veins for frequent blood sampling and/or drug administration.
Therefore, vascular access ports (VAP) are often implanted. Unfortunately,
their use may lead to infection and related complications. For that reason, the
authors of this study evaluated a technique that may limit such problems.
Forty-eight adult male Yucatan miniature
swine were utilized in a diabetes study and an estrogen study, respectively. In
the diabetes study, a 7-French blunt-ended
silicone catheter was advanced into the external jugular vein. In the estrogen
study, again the external jugular vein was catheterized with a 7-French hydrocoated round-tipped polyurethane
catheter.
A subcutaneous pocket was created for the
vascular access port away from the jugular surgical site. The pigs received
prophylactic injections of PenG/Procaine SID for 3 days.
The catheter and port was "locket"
with 50% dextrose in saline containing 200 IU heparin/ml with or without 1mg/ml
vancomycin in a forceful and pulsatile fashion to remove any remaining blood
from the port and catheter. The use of 50% dextrose in saline increases the
viscosity of the "locking" solution and prevents the efflux of
heparin and antibiotic.
Results/Discussion:
Vancomycin added to the heparinized locking
solution reduced the rate of infections by 55% and doubled the duration of
catheter patency. Optimizing catheter placement (i.e. under visualization) and
change to a hydrocoated round-tipped catheter facilitated the improved outcome.
Sterile surgery conditions and reduced
surgery time are crucial for prevention of VAP complications.
The hydrocoated catheter becomes lubricated
upon hydration and subsequently eases insertion and reduces friction. The
rounded tip minimizes the mechanical trauma.
In contrast to the round tip, blunt-ended catheters alter fluid dynamics
at the tip, leading to areas of recirculation and low shear stress. This again
leads to thrombus formation in vitro because of increased platelet residence
time.
The use of a fluoroscope prevents trauma and
facilitatesd placement in a region of turbulent blood flow, minimizing clot
formation.
The regional concentration of antibiotics by
filling the catheter and port is greater than by systemic infusion. Vancomycin
has been shown to have prolonged bioactivity and stability in VAPs.
Confinement of the antibiotic to the lumen of
the catheter, its low concentration, and the administration in 50% dextrose in
saline makes the risk of promoting antibiotic resistance relatively small.
In a different study, it had been
demonstrated that 50% dextrose in saline as locking solutions maintained either
full patency of the catheter or patency after its flushing with a 95% success
rate and the use of heparinized glycerol even a 100% efficiency. This suggests
that glycerol may be an even better locking solution.
Questions:
1.
List at least 3 areas of
research, in which pigs have been extensively utitilized.
2.
What are complications related
to VAP?
3.
Which measurements can minimize
those complications as shown in this study?
Answers:
1. A. Cardiovascular system: hypertension studies,
ventricular arrhythmias,
atherosclerosis,
coronary arterial stenosis and infarction
2.
Access-site cellulites,
bacteremia, septic thrombophlebitis
3. sterile surgical conditions, controlling duration of surgery, choosing optimal surgical and catheter equipment (here hydrocoated round-tipped catheter), atraumatic catheter placement, appropriate locking solution
Safe and effective method for chronic 17b-estradiol administration to mice pp. 33-35
Patients with prostatic cancer have been treated with estrogen therapy. However, one of the side effects of estrogen therapy has been stricture of the anterior urethra.
The mouse has been used as an animal model to study the pathophysiology of this complication resulting from estrogen therapy. Previous studies have shown that estrogen treated male mice have urine retention in the bladder eventually leading to hydronephrotic kidneys. Interestingly, regarding other rodent species, this estrogen effect was limited to mice as estrogen did not induce these negative effects in male hamsters, rats, and guinea pigs.
The objective of this particular study was to determine a safer yet still effective method to chronically treat mice with 17β-estradiol.
The study at hand confirmed the estrogen effect on urine retention, hydronephrosis, and mortality in ovariectomized mice caused by the use of commercially available 1.7 mg SQ 17β-estradiol time-release pellets that are marked as a safe and effective estrogen treatment. Specifically, the time-release pellets were implanted at 4 weeks of age. By 6 month of age, 6 of the 9 mice having received these time-release pellets had died. The remaining 3 mice died by 8 months of age.
To find a treatment regimen for 17β-estradiol that was both safe and physiologically effective, the authors then compared various doses of 17β-estradiol administration via SQ pellets or in drinking water. The results of this study demonstrated that chronic treatment of female, ovariectomized C57BL/6J mice with 17β-estradiol in the drinking water at concentrations of 200 nM to 1 µM did not cause adverse effects and was effective in inducing a uterotrophic response, a marker of estrogen efficacy.
Questions
Question 1: What is the uterotrophic assay?
Question 2: How is the assay conducted?
Question 3: Name three possible explanations given by the authors to explain the absence of adverse effects resulting from the oral estrogen therapy?
Answers:
Answer 1: A screening bioassay to identify estrogen agonists and antagonists.
Answer 2: The mouse is sacrificed and the uterus is removed. The cervix and ovaries are then removed, and the uterus is trimmed free of fat. Uterine weights are then recorded.
Answer 3: The oral therapy is subject to first-pass clearance by the liver which may suppress estrogen levels sufficiently to prevent urine retention but still yield a uterotrophic response; the treatment regimens may affect the production of biologically active estrogen catabolites; the periodic pattern of drinking by the mice would be expected to result in fluctuations in plasma estrogen levels that may prevent the adverse effects whereas the pellets probably produce a constant stream of estrogen release that is less physiological.
Newborn endothelin receptor type B mutant (piebald) mice have a higher resting anal sphincter pressure than newborn C57BL/6 mice pp. 36-38
Hirschsprung's disease is characterized by aganglionosis of the distal colon and hypertonicity of the anal sphincter. Endothelial receptor type (Ednrb) B mutant (piebald) mice phenotypically resemble infants with Hirschsprung's disease in that these mice develop toxic megacolon Because of the absence of ganglion cells in their distal colon. Piebald recessive develop megacolon but piebald lethal usually die by 2 weeks of age. The white spotted coat of the piebalds occurs because of a lack of neural-crest derived enteric ganglia and melanocytes. The endothelial type B mutation disrupts normal migration. Hypothesis tested: Newborn piebald mice would have a higher resting anal sphincter pressure than wild type mice. Technique: One day old neonatal mice were manually restrained in dorsal recumbency and a 24 gauge, open-tip, epidural catheter was inserted into the anus until a deflection was noted on the polygraph pressure monitor. Saline was delivered through the catheter to allow sphincter pressure to be transduced to the monitor. The average of three measurements was taken. The resting anal sphincter pressure of the piebald mice was Significantly greater than that of C57BL/6 J mice and the investigators thought that Ednrb mutants might be a useful animal model for Hirschsprung's disease.Questions:1. Endothelial receptor type (Ednrb) B mutant mice develop megacolon because?2. This anomaly phenotypically resembles what human disease?3. The Ednrb mutants are what coat color?4. Why?Answers:1. They lack ganglion cells in their distal colon.2. Hirschsprung's disease.3. Piebald.4. The endothelial type B mutation disrupts normal migration of the neural crest-derived enteric ganglia and melanocytes.
Effect of hypertension of reproductive organ weights in various strains of rats pp. 39-41
Sprague Dawley rats (SD), Wistar Kyoto rats (WKY), and Spontaneous Hypertensive Rats (SHR) were used in a study evaluating differences in regional vascular resistance. Body weight, organ weight (testes and uteri), and body/tissue weight ratios were compared in the three strains along with their blood pressure. Testicular weight in the WKY and SHR was lower than in the SD. The testes/ body weight ratio was higher in the WKY and less in the SD and SHR. The body weight was higher in both the males and females SD and lower in the WKY and SHR. However, the body weight of the three female strains showed no significant difference but the uterus weight was larger in the SHR than in the SD and WKY. The systolic and diastolic blood pressure was higher in the male and female SHR than in the SD and WKY strains. This research indicates strain-specific differences in body weight of different organs and organ/body weight ratio. The testes reacted to hypertension in the WKY and the SHR strains increasing in size relative to body weight while the uteri in the females did not. Therefore, the hypertension affected the testes more than the uteri. This study shows the effect of hypertension should be considered when choosing a species, gender or organ for study.
Questions:
1. The testes were smaller in which two strains?
a. SD & WKY
b. SD & SHR
c. SHR & WKY
2. There was no significant difference in the uterine size of the three strains involved with this study.
a. True
b. False
3. The effects of hypertension should be considered when choosing species, gender or an organ for study.
a.
True
b.
False
Answers:
1.
c
2.
a
3.
a
A simple, inexpensive method to minimize floor-drain obstructions while supporting environmental enrichment in primate facilities pp 42-45
An important component of nonhuman primate environmental enrichment programs is affording the animals the opportunity to manipulate objects. Although these objects and various bulky food items enrich the quality of life for nonhuman primates, they complicate the duties of facility maintenance personnel. A prime example of these sometimes costly complications is a seemingly never-ending series of floor drain obstructions. We devised a simple, inexpensive modified drain cover that prevents large items from entering the drain. The total cost of materials for this device was $1.12, and it required only 15 min of labor for assembly. The design and implementation of this modified drain cover illustrate why the interaction between physical-plant personnel and animal-care personnel is key to the operation of a successful animal care and use program and proper maintenance of laboratory animal facilities. Relevant Background1. "Biomedical experiments are conducted in accordance with the principles of the scientific method developed by the French physiologist, Claude Bernard, in 1865. This method established two requirements for The conduct of a valid experiment: (1) control of all variables so that only one factor or set of factors is changed at a time, and (2) the replication of results by other laboratories. Unless these requirements are met, an experiment is not considered valid. ... Stressed animals do not make good research subjects." 12 "We should make use of information on a species natural history to improve management and enrich environments, because physical and psychological well-being are essential not only to the health of the animals but also to the validity of the research results." 23. "Whenever possible, primate conspecifics should be housed together in social groups because of their social needs, and these needs should not take second place to housing systems designed primarily for the convenience of animal care technicians. Independent of ethical considerations, to deprive a gregarious animal of its basic behavioral, emotional, and social needs is no less detrimental to the validity of many scientific investigations than deprivation of light, fresh air, food and water." 34. "A good management program provides the environment, housing, and care that ... minimizes variations that can affect research. ... Animals should be housed with the goal of maximizing species-specific behaviors and minimizing stress-induced behaviors." 4 An important components of nonhuman primate environmental enrichment program is affording the animals the opportunity to manipulate objects, such as rubber and metallic toys, polyvinyl chloride food puzzles, chains, and mirrors, along with bulky pieces of raw produce to introduce variety into their diet. Although these items are important for enrichment, they also complicate the day-to-day duties of facility maintenance personnel. A prime example of this is a never ending series of floor drain obstructions. Most floor drains, defined as any pipe that carries waste or waterborne wastes in a building drainage system, includes a drain basket, slotted drain cover, and a P-trap that is constructed to provide a liquid seal that will prevent back passage of air without materially affected the flow of sewage or waste water through it. A surprisingly wide variety of objects can be washed or thrown by monkeys down a 10.16 cm opening during cleaning. These include pieces of produce (cabbage, oranges), polyvinyl chloride food puzzles, rubber toys, padlocks, and hose nozzles. Large objects can become wedged in the curve of the P-trap and may serve as a nidus for obstructions that can be extremely costly and time-consuming to resolve. This article describes a simple, inexpensive modified drain cover that prevents large items from entering the drain and the P-trap. This device replaces both the slotted drain cover and the drain basket. The device is a 5.08 cm section of black seamless steel pipe with two zinc-coated bolts (12.7 cm in length, 0.64 cm diameter) welded perpendicular to one another across the opening of the pipe section. The bolts provide a barrier that stops large items from entering the drain and position the device so that is rests securely in the drain cavity when the basket and slotted drain cover are removed. The authors state that their modified drain cover has been in use in 55 floor drains for 7 months and has substantially reduced the number and severity of drain obstructions at their facility.Questions:
1. Environmental enhancement and promotion of the psychologicalwell-being of nonhuman primates are specifically mandated by the AnimalWelfare Act. (True or False)2. The National Research Council's Guide for the Care and User of Laboratory Animals emphasizes the importance of the physical plant to a properly managed laboratory animal facility. The interaction between physical-plant personnel and animal-care personnel is key to the successful operation of an animal care and use program. (True or False)Answers:
1. True2. TrueReferences1. American Medical Association 1992. Use of Animals in Biomedical Research - The Challenge and Response - An American Medical Association White Paper. AMA. Group on Science and Technology, Chicago2. American Society of Primatologists 2000. American Society ofPrimatologists guidelines for the ethical treatment of nonhuman primates. ASP Bulletin 24(4), 43. Animal Welfare Institute 1979. Comfortable Quarters for Laboratory Animals, Seventh Edition. Animal Welfare Institute, Washington4. National Research Council 1996. Guide for the Care and Use ofLaboratory Animals <http://www.nap.edu/readingroom/books/labrats/> , 7th Edition. National Academy Press, Washington
Pancreatic islet cell tumor in a domestic ferret pp. 46-48
Clinical report of an insulinoma in
a ferret in a research colony. A five year old male ferret was noted to
be experiencing episodic lethargy, hind limb weakness and ataxia. Weight
loss had also been noted. The only abnormality noted on CBC &
chemistry panel was a blood glucose level of 47 mg/dl (normal:
80-120mg/dl). Periodic repeated glucose levels revealed persistent
hypoglycemia. Insulinoma was suspected, the animal was euthanized and a
necropsy was performed.
Necropsy revealed pancreatic nodules
and the liver had multifocal pale foci diffusely distributed.
Histopathology revealed pancreatic islet cell tumors in the pancreas along with
hyperplastic islets of Langerhans and nodular exocrine acinar
hyperplasia. The liver revealed vacuolar changes likely due to fat store
mobilization and metabolic changes.
Pancreatic islet cell tumors
(insulinomas) are one of the most common neoplasms in ferrets. They occur
in middle-aged to older animals. They typically occur as discrete nodules
of pancreatic islets and typically secrete insulin autonomously. This
should be contrasted to acinar hyperplasia, expansion of exocrine tissue where
islets are unapparent. Acinar hyperplasia is a common incidental finding
in ferrets.
Clinical signs of these
tumors: weakness, ataxia, tremors, posterior paresis, collapse, seizures,
weight loss, vomiting, ptyalism and mouth pawing.
Laboratory abnormality:
hypoglycemia - may need a 4-hour fasting sample to document
Differentials for
hypoglycemia: hepatic dysfunction, pregnancy toxemia, sepsis,
hypoadrenocorticism, starvation, malabsorption and extrapancreatic
tumor-related hypoglycemia
Treatments:
medical: Dietary management - free choice food or 3-4 daily meals
Prednisone - inhibits peripheral uptake of glucose and stimulates
hepatic gluconeogenesis and
glycogenolysis
Diazoxide - benzothiadiazide derivative, suppresses insulin secretion by
the pancreatic beta cells,
enhances hepatic gluconeogenesis and glycogenolysis and reduces the cellular
uptake of glucose
Octreotide - somatostatin analogue - suppresses insulin secretion;
equivocal results in use in ferrets
surgical - nodulectomy combined with partial pancreatectomy - shows increased
disease-free and survival times
vs. nodulectomy only
Metastasis is rare, but local
recurrence is common.
Questions:
1. What is the most common laboratory abnormality associated with
insulinomas?
2. What is a rare, but
potential result of surgical removal/debulking of these tumors?
Answers:
1. Hypoglycemia
2. Diabetes Mellitus
The rotarod pp. 49
The rotarod, also known as the
rotarod test, is used as a basic assessment tool for coordination and balance
in rodents and provides one measure of locomotor ability. Additional behavioral
tests that assess locomotor ability include the open field assessment, the
balance beam, the hanging wire/ grip test, the vertical pole test, and walking
pattern analysis. In its most basic form, the rotarod is comprised of a
rotating cylinder typically 3-3.5 cm in diameter for mice and 7-7.5 cm in
diameter for rats, upon which an animal is placed. As the cylinder rotates
(solid rubber), the animal must move forward to keep from falling off the
cylinder. The cylinder is elevated above a padded landing area to reduce the
risk of injury to animals that fall. Animals with deficits affecting balance or
coordination fall from the apparatus more quickly than animals with normal
motor function. The rotarod has been proposed as one of a number of behavioral
tests for phenotyping genetically modified mice. Animals with experimentally
induced lesions to the CNS and animals receiving therapeutic and experimental
compounds may also be tested for motor deficits using the rotarod.
Questions:
1) Name the
behavioral tests that are used to assess locomotor ability?
2) Rotarod can be used to test_________________
Answers:
1)
Open filed assessment, the balance beam, the hanging wire, grip test, vertical
pole test, and walking pattern analysis and rotarod test.
2)
Locomotor ability.