Wire-bottom versus solid-bottom rodent caging issues important to scientists and laboratory animal science specialists. Contemporary Topics 40(6), 11.
Abstract: A review article based on a survery in 1999 of toxicology facilities and their choice of housing rats. The survey showed that more than 80% were housed on wire-bottom cages. The "Guide" states: "Rodents are often housed on wire flooring, which enhances sanitation of the cage by enabling urine and feces to pass through to a collection tray. However, some evidence suggests that solid-bottom caging, with bedding, is preferred by rodents. Solid bottom caging with bedding is therefore recommended for rodents". It also sates that "IACUC review of this aspect of the animal care program should ensure that caging enhances animal well-being consistane with good sanitation and the requirements of the reseach project". Several references provide evidence of pathologic changes associated with rodents held in wire-bottom caging. Some microscopic changes to nerve tissue have been documented to occur within weeks of housing on wire. Foot lesions on rats housed on wire over 1 year are significantly common. Preference testing between solid and wire has indicated a preference for solid with bedding when animals are resting. When awake rats were shown to acually play longer and engage in more species typical rank-indicating behaviours when on wire, and prefer wire over solid. However no evidence can be documented showing any differences in BW, water consumption, physiologic data, or ease of handling with either housing type. There is evidence that thermoregulation and metabolic responses are affected by the presence or absence of bedding. Toxocologists prefer wire caging because of ease of sanitation, better animal health assessment, serviceability of equipment, labour savings, controlled exposure to drug and drug metabolites, more accurate feed consumptiojn data, reduced staff allergies, elimination of bedding ingestion as an expt variable, better air circulation and ammonia control, denser cage census, reduced fecal and urine exposure, no significant watering-based accidents, and existing baseline data. Preferences of toxocologists for solid cages were based on; reduction of limb lesions, improved thermoregulation, better health assessment capabilities, easier group housing, reduced lighting exposure, potential use within an isolator, and global pressure. The total replacement capital costs to the major US based pharmaceutical company toxicology programs is estimated to be greater than $16 million to convert from wire to solid. The esimtated costs are based on purchase of new plastic caging and racks to place them on. However other increases in costs are expected due to higher perdiems for higher maintenance costs, more frequent cage changing, cost of bedding, cage set up time , and cage replacement every 2.5 years. Cage wash schedules are more intensive for solid-bottom than for wire. . The paper summarizes by stating that there is no compelling scientific evidence that wire-bottom caging is inappropriate for rodent housing of less than 1 year duration. The addition of a resting board may address the foot lesions. The mere preference of an animal for one type of caging over another does not automatically mean that caging is best for all animals in most situations. The paper also states that the increase in labour costs, and potential staff health problems are higher for solid bottom. It cautions the lab animal community to proceed slowly when deciding to convert to solid when the inital costs to the industry are so high, and the scientific evidence to the betterment of the animals is not overwelming. The paper states that IACUC committees must make independent reviews of each protocol and decide caging type based on experimental, animal-welfare, and regulatory needs.
Questions: 1. Does the Guide recommend wire caging or solid bottom with bedding?
2. The guide defers the decision of caging to who?
3. In preference tesing when rats are awake they prefer which flooring? when resting?
4. State some important reasons why toxicologists prefer wire bottom caging?
5. What is the major health risk associated with wire and when does it occur?
Answers: 1. Recommend solid with bedding
2. The IACUC
3. wire., solid
4.Controlled exposure to drugs and drug metabolites, elimination of bedding ingestion as an experimental variable, more accurate feed consumption data
5. Foot leasion at 1 year +
Regarding the inadvisability of administering postoperative analgesics in the drinking water of rats (Rattus norvegicus). Contemporary Topics 40(6), 15.
Abstract: This study looked at the feasibility of administering analgesics in the drinking water to rats for 5 days postoperatively. Two groups composed of 5 naive female rats were given one of two formulations of acetaminophen: 1) pediatric cherry flavored oral suspension (32 mg/ml) 2) adult alcohol containing preparation (33 mg/ml). Both formulations were diluted to 6 mg/ml using normal drinking water, for a daily dose of 334 mg/kg. Consumption of acetaminophen solutions and food intake were measured during a 24 hour period. Results: Fluid intake on day one was significantly decreased in rats receiving both the cherry flavored (51% reduction from pre acetaminophen level) and alcohol containing preparation (40% reduction from pre acetaminophen level). Both groups demonstrated a significant rebound increase in water consumption during the first day of treatment. On days 2 through 5, the fluid intake of both groups was similar to pre treatment levels. Feed intake was a significantly reduced in animals on the cherry flavored suspension. In summary, due to the neophobic nature of rodents and subsequent inability to ensure an efficacious analgesic dose, administration of acetaminophen via the drinking water is not recommended.
Questions: 1. How can a conditioned taste aversion develop ?
2. What advantage does acetaminophen possess compared to other NSAIDS ?
Answers: 1. If an animal ingests a novel substance while it is sick, or becomes sick soon after its ingestion.
2. Acetaminophen does not possess anticoagulant properties.
Biodecontamination for Animal Rooms and Heat-Sensitive Equipment with Vaporized Hydrogen Peroxide. Contemporary Topics 40(6), 18.
Abstract: Vaporized hydrogen peroxide system (VHP 1000 Biodecontamination System) was successfully used to decontaminate an animal room. This system is a compact, mobile unit that generates and controls VHP delivery into an enclosed environment and can be hooked directly to the ventilation system. It maintains the concentration and humidity below the dew point of VHP so that it does not condense (puddle).
The system runs through a 3 hour cycle that consists of:
· Dehumidification
· Conditioning - VHP is introduced by vaporization
· Decontamination - circulating VHP concentration is maintained by introducing a controlled concentration and catalytically degrading VHP in the returning air line
· Aeration - VHP is no longer added to the system and recirculating VHP is either degraded or blown out the ducts
Hydrogen peroxide is sporicidal at low vapor concentrations; this is not true of the liquid state. The effectiveness of this treatment was tested with chemical and biological indicators (Bacillus stearothermophilus) placed throughout the room. Surface contamination was monitored with Rodac plates (Replicate Organism Detection and Counting)
Hydrogen peroxide breaks down to water and oxygen (non-toxic). Formaldehyde fumigation which is commonly used, needs to be cleaned up by hand and leaves hexamethylene-tetramine salt on all surfaces. Ethylene oxide is another fumigating compound that can be used to disinfect but is less popular because of its toxic properties.
Questions: 1. Which of the following is used to monitor the effectiveness of hydrogen peroxide decontamination.
A. Bacillus subtillis
B. Bacillus piliformis
C. Bacillus stearothermophilus
D. Bacillus anthracisis
2. Which of the following is not an advantage of vaporized hydrogen peroxide when compared to formaldehyde fumigation.
A. less toxic
B. less expensive
C. rapid
D. no residues formed
3. Which of the following statements is false in regards to automated vaporized hydrogen peroxidase decontamination of a room:
A. Does not require pre-cleaning before use
B. The room is dehumidified before HP is added
C. The system breaks HP down into water and oxygen
D. Is effective in killing bacterial spores
Answers: 1. C
2. B
3. A
Tapeworm identification in the fat sand rat (Psammomys obesus obesus). Contemporary Topics 40(6), 22.
Abstract: Rodentolepis nana (formerly Hymenolepis nana) was found in a colony of fat sand rats, but its identification was complicated due to the unexpected longer length of the cestode.
The sand rats were used for intervertebral disc research and some of these animals exhibited weight loss, decreased appetite, and premature death. R. nana eggs were found on fecal flotation. The cestodes' rostellums were armed with 24 hooks. These tapeworms were as long as 150 mm, much longer than the 25-40 mm listed for mice and the 7-100 mm listed for rats in the parasitology literature for the "dwarf tapeworm." The size of this parasite is reported to be influenced by the definitive host and the quality of the host's carbohydrate diet. Therefore, looking eggs with polar filaments and counting rostellar hooks should be the primary method of classification; not measuring the length of the cestode.
This hymenolepid tapeworm may use fleas and grain beetles as intermediate hosts. However, R. nana is the only tapeworm able to infect its definitive host (sand rat) without an intermediate host. After the eggs are ingested, oncospheres hatch from the egg, penetrate the small intestinal mucosa and develop into a cysticercoid in a lacteal. These re-enter the lumen and become gravid eggs, which are shed within 2 weeks of the rodent becoming infected. Autoinfection can occur when eggs hatch as they pass through the small intestine and never exit the body.
R. nana is zoonotic and may be found in pet store rats, mice, hamsters, and prairie dogs. The infection can be difficult to eliminate in rodent colonies. However, two courses of Droncit (0.1 ml SQ, spaced 2 months apart) was successful in eliminating the parasite in the reported sand rat colony.
A note on the fat sand rat: this species undergoes age-related spontaneous disc degeneration, which makes it an important model for orthopedic studies. It is also a model for cataract formation, arteriosclerosis, and type II diabetes. The Purina sand rat diet #5L09 is a special low-calorie formulation, which prevents the development of the diabetes seen when feeding high-calorie diets ad libitum.
Questions: 1) What is the former name of Rodentolepis nana?
2) What stage of R. nana's life cycle enters the small intestinal mucosa?
3) The fat sand rat serves as a model for which types of studies?
4) What is the scientific name for the fat sand rat?
Answers: 1) Hymenolepis nana
2) Oncosphere
3) Spontaneous disc degeneration, type II diabetes, cataract formation, arteriosclerosis
4) Psammomys obesus obesus
Changes in the weights of the accessory sex organs in male CD/IGS rats (Rattus norvegicus) after castration. Contemporary Topics 40(6), 25.
Abstract: The Hershberger assay is used for measuring androgenic or antiandrogenic properties of compounds. This model uses a castrated male rat which has chemicals administered for a specific period of time. The Organization for Cooperation and Development (OCED) has proposed the use of rats which have been acclimated for one to two weeks after castration. Accessory sex glands that have not atrophied sufficiently have an affect on the sensitivity of the test. In this study 5 week old Crj:CD IGS rats were castrated at five weeks of age and were euthanized from 0 to 14 days after castration. The ventral prostate, vesicular gland, bulbospongiosus/levator ani muscle, glans penis and bulbourethral glands were weighed. The ventral prostate and vesicular gland had significantly decreased in weight 8 and 6 days respectively. The other organs did not decease significantly between time periods though there was an overall decrease in weight. The authors suggested castrated rats should be allowed to recover for a period greater than 8 days before they are used in the Hershberger assay.
Questions: 1. The Hershberger assay is used to measure what properties of compounds?
2. The authors of this research recommended using castrated rats which have been acclimated for a time greater than
a. 2 days
b. 4 days
c. 6 days
d. 8 days.
3. Which organs had the most significant decrease in weight at 8 and 6 days?
Answers: 1. androgenic and antiandrogenic compounds
2. 8 days
3. ventral prostate and vesicular gland
Improved procedure and cannula design for simple-T cannulation at the distal ileum in growing pigs. Contemporary Topics 40(6), 27.
Abstract: Device and Modifications: Cannulae were fabricated from nylon with an 8 cm by 3 cm flange that was inserted into the ileum and
against which double purse string sutures secured the intestinal segment. The barrel of the cannula was threaded for receiving a
threaded ring screwed down the cannula barrel on the external surface to firmly fix the cannula against the body wall. In this
modification, the ring had notches for accepting a spanner wrench for adjustment. In addition, this modification incorporated the use of
a nylon "plug" which fit the cannula barrel with a narrow tolerance and prevented intestinal digesta from leaking on the skin surfaces.
Operative/Post-operative Modifications: In this surgical model, cannulae were exteriorized between the last two ribs. In the
authors' opinion, this maneuver greatly stabilized the cannula and relieved some incisional stress from the weight of the cannula barrel
and plug.
The authors also believe that the success of their technique and complete recovery (defined by them as a return to feed consumption of
the presurgical feed intake, 5% of body weight in seven days) to five days of organic iodine washes of the exteriorized cannulae and
then continued twice daily washes with soapy warm water. Their contention was further supported, at necropsy, when the weight of
the pigs indicated that the growth curve for these 15 pigs was very close to that cited by the NRC for this breed of swine.
Questions: 1. The ________________ part of the porcine colon is anatomically configured in a special way compared to other mammals and given the common name, ____________.
2. Give the number or rib pairs cited by anatomy texts, these authors placed the cannulae between the _____________________.
a. 14th and 15th
c. 12th and 13th
d. 11th and 12th
3. When surgically placing cannulas in the intestinal tract of any animal, incisions should be limited to the __________________ side of the intestinal segment.
Answers: 1. ascending: spiral
2. (a) 14th-15th
3. Antimesenteric
Fibroma (myxoma) molle in a hamster (Mescricetus auratus). Contemporary Topics 40(6), 32.
Abstract: This is a case report of a Fibroma Molle in the cheek pouch of a Syrian hamster. The mass had initially presented as a white papule that could be observed when the cheek pouch was everted. It grew to a size of 5X3X5 mm in 6-9 weeks. Grossly, the mass was white, well-encapsulated, multilobulated and pedunculated. Differential diagnoses for an oral mass in the cheek pouch of a rodent include a benign reactive lesion from a friction mechanism; foreign body granuloma; abscess caused by a microorganism such as Staphylococcus or Streptococcus; periodontitis; tumor of viral origin or tumor of mesenchymal origin. Oral tumor in hamsters can be classified into 3 main categories; spontaneous, caused by chemical or physical agents; or due to viral agents such as SV 40, SV5, polyoma virus, adenovirus, herpes virus or murine sarcoma virus. An excisional biopsy was diagnostic for a fibroma (myxoma) molle based on histopathology. The mass consisted of loosely arranged bundles of interdigitating spindle to stellate cells, and eosinophilic strands of collagen. Using Alcian Blue/PAS staining, extracellular ground substances consistent with acid mucopolysaccharide (blue amorphous material) was identified.
Hamsters have a relatively low incidence of tumors (3.7% malignancies). The cheek pouch is the primary site for connective tumors of mesenchymal origin. In humans, fibromas are one of the most common benign growths of the oral mucosa.
Questions: 1) What is the genus and species of the Syrian hamster?
2) True/False Tumors of the oral cavity are relatively common in the hamster.
Answers: 1) Mesocricetus auratus
2) False
Treatment of Argulus sp. infestation of river frogs. Contemporary Topics 40(6), 35.
Abstract: Argulus, also known as fish louse, commonly infests saltwater and freshwater fishes and normally inhabit the skin, gills and buccal cavity. Adult parasite is dorsoventrally flattened and oval about 6 to 10 mm in lenght and can be seen without magnification. Its preoral sting penetrate the skin and deliver a cytolytic toxin to kill larval fish. These parasites feed on host's blood. Clinical signs are reported to be repeated trauma, erratic swimming and poor growth in fishes. Skin may become ulcerated and susceptible to secondary infections including bacterial, fungal and viral. Life cycle of this parasite is direct and takes about 40 to 100 days.
This article describes the Argulus sp. infestation of River Frogs. Skin scrapings from Ten mature (2-3 yrs of age) river frog tadpoes (Rana hecksheri) showed numerous immature and adult Argulus sp on the tails and dorsal trunks. The river frogs were collected from Pointsett State in South Carolina and house in a tank at the North Carolina Zoological Park. The treatment included manual removal of adult parsites and the treatment of tadpole with lufenuron (15 mg/l) and sodium chloride in the tank water for 3 weeks. Skin scrapings repeated on days 2, 10, 18 and 28 after the initiation of treatment. No parasites were seen after day 2 of treatment. There were no deleterious effects of the treatment noted. Lufenuron prevent larval insects and crustaceans from developing into adults by inhibiting the synthesis, polymerization and deposition of chitin. Lufenuron has been used in dogs and cats to prevent flea infestations. This is the first report of treatment on Argulus infestation in amphibians.
Questions: 1. True/false: Argulus, also known as fish louse, commonly infests saltwater and freshwater fishes; and adults can not be seen without
magnification.
2. True/False: Argulus infestations in amphibians can be successfuly treated with lufenuron.
3. True/False: Argulus has indirect life cycle.
4. What is the mechanism of action of lufenuron.
Answers: 1. False: Argulus, also known as fish louse, commonly infests saltwater and
freshwater fishes and adults can be seen without magnification.
2. True
3. False: Argulus has direct life cycle.
4. Lufenuron prevent larval insects and crustaceans from developing into adults by inhibiting the synthesis, polymerization and deposition of chitin.
Adaptation of a dental radiovisiograph unit as a laboratory animal research tool. Contemporary Topics 40(6), 37.
Abstract: The authors used a digital radiography system designed for dentistry to assess various skeletal and soft tissue parameters in rabbits, rats and mice. Examples of uses included assessment of fractures, implant placement, and ossification in rabbit tibias; evaluation of bone fill in rat cranial defects; assurance of proper placement of oral gavage tubes in mice and rats. Oral contrast material allowed imaging of the GIT and IV contrast allowed imaging of the kidneys and bladder in rodents. They were able to use the instrument and software programs without modifications. Additional software allowed assessment of bone density. The unit included a digital camera. The unit also included 2 sensors which serve as replacements for radiographic film. The sensors are X-ray-sensitive charge coupled devices. They record a digital image which is viewable as a radiograph-like image on a computer screen. Advantages: Instantaneous digital radiographs Does not require wall shielding or a dedicated X-ray suite Does not require film processing equipment Reduces scatter radiation by < 95% Excellent contrast and resolution of bony changes in rodents Inexpensive at <$15,000. Disadvantages Not a substitute for bone mineral density assessment with DEXA or CT Small size of sensors limits the size of the body part to be imaged The mA and kVp are fixed and exposure time is the only method available to vary total exposure The limitation on total exposure can limit clarity of soft tissue images or other subtle changes Digital radiographs printed on plain paper lack the clarity of those on a computer screen The unit's software stores images by dental tooth number
Questions: 1. What is the National Council of Radiation Protection limit on annual exposure from X-ray equipment in a unrestricted areas?
2. What is DEXA?
3. What does an X-ray-sensitive charge-coupled device do?
Answers: 1. 100 mRem annually
2. Dual energy X-ray absorptiometry
3. Records a digitial image and converts it to a radiograph-like image on a computer screen.
Electronic imaging system incorporating a hand-held fundus camera for canine ophthalmology. Contemporary Topics 40(6), 41.
Abstract: A hand-held fundus camera combined with an electronic imaging system was used to collect images of the canine ocular fundus. The electronic imaging system was made up of a hand-held fundus camera, an IBM personal computer, Microsoft Windows NT, Adobe Photoshop, and color printer. The system allowed for capture of fundic images and conversion to a digital image. The images could be stored in electronic format, edited, and printed.
Questions: 1. What is the genus and species of the dog?
2. Which of the following is not an advantage of the electronic imaging system:
a. continual imaging of the retina can be performed
b. images can be stored in a compact amount of space
c. data collection costs in canine ophthalmology are markedly reduced
d. the electronic imaging system requires more time to generate photos than traditional photography using film.
Answers: 1. Canis familiaris
2. The electronic imaging system is faster than traditional photography using film