Chapter Twenty-Nine

Chapter Twenty-Nine Miscellaneous Laboratory Animals Part 2

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Fish • Nest materials - sand, gravel & rocks, plant matter, kidney secretions, mucus cocoons & mucous-coated air bubbles • Lay eggs 2 - 3, to millions, some bear live young • Studies of temperature & electrolyte regulation, endocrinology, bacterial diseases, behavior, genetics & water pollution • rainbow trout - studies of liver cancer • live-bearing tropical fishes - studies of melanomas • goldfish in neurological & vision studies • Criteria for selecting include availability, survivability in aquariums, & background or amount of baseline information available.

Fish Handling & Restraint • Identify w/ numbered jaw tags, button tags inserted through fins or an operculum, freeze branding, fin clipping and pigmentation patterns. • Wild-caught - no mud on gills & not injured, no damage to protective mucus coat • Not kept out of water more than a few seconds, without equipment to keep their body & gills moist • Temperature, pH & O2 level of transport water should not vary from water taken from. • Plastic bags & Styrofoam boxes for transport • Shipment requires water oxygenation system. • Can use anesthetics for long-distance shipment

(Images) Zebra Fish Equipment Views of a zebra fish room...

(Image) Zebra Fish

Fish Behavior • Watch out for - food refusal, abnormal posture, erratic movements, gulping air at water surface, scraping against objects, jumping out of water & listlessness. • Some fishes aggressively defend territories; crowding causes greater aggressiveness. • Inquisitive & mobile • Behavior changes with reproduction or feeding. • Interspecies and inter-species fighting occurs. • Reduce by separating aggressive individuals & house compatible species w/ similar requirements.

Fish Husbandry • Optimal housing = easy to clean, or self-cleaning, & regulation of water composition & flow rate • inexpensive, non-corrosive & provide adequate temperature / O2 control • Circular tank for continuous swimmers • For bottom feeders, a large bottom area > important than high water column. • Some have higher O2 requirements. • > surface area allows > O2 to be absorbed into water than deeper vessel of same capacity.

Fish Husbandry II • Important considerations: chemical and physical characteristics of water • Require certain levels of acidity or alkalinity, dissolved O2 , salts, electrolytes, specific range of water temp & circulation • Treat chlorine water with sodium thiosulfate or hold 24 hours before use. • allows chlorine to dissipate into air • Activated carbon used in filter to remove certain types of ions or toxins. • Plumbing fixtures, tanks, pond liners and water should not contain or release toxic substances.

Fish Husbandry III • Fluorescent lighting for aquariums • less heat & greater control of light spectrum • Avoid direct sunlight - heat not controlled, nor effect on microorganism growth • Quarantine new arrivals for 3 wks. • Disinfectants = alcohol or potassium permanganate • Flush tanks well with clean water before reintroducing. • Fish poisoned by small amount of residual soap. • Species population density tolerances • 2 rules: 1 gm fish per liter or 2.5 centimeters of fish per 4 liters of water

Fish Husbandry IV • Extract O2 from water through gills; highly vascularized filaments in gill cavities. • In aquarium, movement is by bubbling air through water. • Water contains ~8 to 11 ppm of O2. • Lungfishes have accessory air-breathing organs. • CO2 content of water limits oxygenation - never allowed > 15 ppm. • Recirculation - - pumping system removes water from tank, forces it through filter, cleans water mechanically, chemically & biologically. • Recirculated water lessens volume of water used.

Fish Diet • Adults usually fed 1x / day. • Give quantity to allow feeding less than 10 min. • Siphon or scoop out any food left over. • Feed young, growing fishes 3x / day. • Food = compounded powder, pellets or flakes, or fresh food such as shrimp, brine shrimp, other fish, insects or vegetables • Automatic feeders are available. • Water temperature & O2 impact feeding behavior. • Sinking pelleted feed for bottom feeders, floating pelleted feed for surface feeders, slowly sinking flaked food for small fishes

Ferrets • Ferret is a mustelid carnivore; belongs to family Mustelidae with otters, weasels, & mink • Studies on pathology & immunology of viral diseases, reproduction, control of breeding season by day-length change, growth & pelt cycles. • dental & experimental teratology research, testing drugs & as alternative to cats

(Image) Ferret

Ferret Handling & Restraint • After adjusting, handle without difficulty & restraint gloves. Females with babies are aggressive. • Hold adult by grasping it behind front extremities with 1 hand & holding hind legs with other hand. • 1 hand across shoulders, thumb & forefinger around neck, other fingers around chest behind forelimb • Held by loose skin in back of neck, animal will relax & simple procedures can be performed. • Foul-smelling substance may be emitted (not sprayed) from scent glands located on either side of anus.

Ferret Sexing & Breeding • Male - hobs weigh 3 - 6 lb. • Female - jills weigh 1 - 2 lb. • Lose weight in breeding season & gain in fall. • Testes of immature males are small and firm; in older males they are longer & flabby. • Male ventrally situated penis as a dog’s with testicles close to anus. • Female vulva after estrus - trace of swelling & wrinkled • An induced ovulator

Ferret Husbandry • Kept in cat or rabbit cage w/ close-fitting door & narrow bar spaces • If rabbit cage, lower part of opening inside door must be closed with strip of metal to retain bedding. • Top-filled food hopper without cover not satisfactory; can easily crawl through when empty. • Wood chips an economical bedding. • Prefer to have a nest box to sleep. • Feed a commercial ferret diet.

Chinchillas • Belongs to same family as guinea pig • Normal wild color is a smoky blue-gray. • Nutrition studies, studies of middle & inner ear • Caution in handling because of risk of fur-slip. • release fur when attacked or frightened • To pick up, tail is grasped and animal swung onto opposite forearm & held against handler’s body where it will usually sit quietly.

(Image) Chinchilla

Chinchilla Husbandry • Adults, especially females , aggressive & may have to be caged individually. • commonly maintained in pairs • Wide variety of caging with solid or mesh bottoms • mesh is more suitable, since cleaning is easier • Takes dust bath; fur appears matted & rough without frequent access. • A pan or box with a mixture of Fuller’s earth & white sand placed in pen daily. • If dust bath is left in pen, there is a perpetual cloud of dust in room, as they are active in their dusting and grooming habits.

Chinchilla Diet • Commercial chinchilla pellets • long, thin capsules, grasped readily in one forepaw • Grasp food with paws & may throw pellets • Some breeders feed only commercially prepared food, giving no hay or greens. • Other breeders believe that hay is necessary for nutritional or behavioral reasons. • Some believe that best results are obtained by using vitamin or protein supplements.

Woodchucks • Rodent family • Used to study hepatitis B, obesity & energy balance, endocrine & metabolism function, central nervous system control • Hibernate, body temp can be as low as 33°F • Studies of heart, kidney & metabolic functions at low body temp with hibernating woodchucks

(Images) Woodchucks

Woodchuck Handling & Restraint • When disturbed, they click their incisors rapidly & emit sharp barks & shrill whistles. • Handled without difficulty if calm & firm approach. • Wear protective gloves at all times. • Restraint • Force down by sliding gloved hand over animal, immobilize head & shoulders with gloved hand, grasp base of tail tightly with other hand. • Lift hind legs & remove from cage, carry by tail • If accustomed to handling, support by gloved hand underneath thorax. • Box with door a hiding place & provides enrichment • an easy and less stressful way to transport animal

Woodchuck Husbandry • Adults may be housed in standard metal cages designed for cats, dogs or rabbits. • Doors must latch securely. Food & water bowls & cage floors clamped so cannot be pushed or slid out. • Squeeze through any hole large enough for head. • Raised flooring is preferable to contact bedding, as animals kick bedding from cages. • Adult s can be housed in groups in large cages. • Housing in groups less than 2 may result in food monopolization by dominant individuals. • Adult males must be housed individually. • Place each male with 1 female mate.

Woodchuck Diet • Nutritional requirements unknown. • Standard zoo diet = green veggies, apples & grains . • or diet of ground grains + peanut & soybean meal • A diet of canned creamed corn, cornmeal, apples, cabbage & bread has been used • Commercial rabbit pellets, made into blocks (9 x 16 mm oval), recently introduced. • This form reduces spillage, facilitates food consumption measurements, & forces animal to gnaw, helping to keep their incisors at proper length.

Opossums • The only North American marsupial • Marsupials s have pouch where young carried. • Some 90 living species in 11 families; found mainly in Australia, in South & Central America. • Wild caught North American opossums used. • Not bred in captivity to develop any special strain. • Experimental studies in developmental biology • Young born premature (12–13 days gestation). • Used to study fetal development outside uterus. • Brazilian gray short-tailed is hamster-sized, no pouch, carries young on abdomen; young readily accessible for study.

Opossum Handling & Restraint • In daytime, fairly sluggish. If tipped from its nest box, will stand hissing, mouth open, drooling. • At night, more aggressive & active. • Large & powerful jaw muscles • Heavy leather gloves not complete protection • To remove, distract it while reaching for tail. • Prevent toenails from being torn from nail beds when lifting from wire bottom cage. • Flat paddle may be inserted beneath feet while exerting tension on tail. • Continuous, gentle shaking while carried by tail to prevent animal from climbing its own tail.

Opossum Husbandry & Diet • Dog, cat and rabbit cages are suitable. • Provide a shelf for climbing. • If in groups, provide nest box for each animal to minimize fighting. • Brazilian opossums can be housed in rat cages. • Wide range of food in wild: insects, earthworms, small vertebrates, fruits & grass. • In laboratories they are fed commercially prepared dog or cat food, wet or dry.

Armadillos • Nine-banded included in anteaters & sloth group • Susceptible to leprosy & is first unaltered model capable of developing form of disease that is difficult to treat. • Important characteristics for research are: • production of monozygous quadruplet young • simple uterus similar to human • implantation delay of the blastocysts • low body temperature of 80 to 97.5°F • ability to build up an oxygen debt • band patterns on the shell which readily mutate • primitive immune response

Armadillo Handling & Restraint • Powerful back legs & sharp claws, heavy gloves should be used for manual restraint. • Pick up by sides of carapace or lift by tail base. • Cannot be kept on bare concrete or wire-mesh floor - develop sore feet from attempts to dig. • Commercial polyethylene kennel for shipment of animals by air provides inexpensive, sanitizable cage & only limited space is required. • Modification required is covering lower half of grilled door w/ metal sheet to prevent kicking out bedding.

Armadillo Diet • In the wild, eat insects. • Traditional captive diet = milk, eggs, & chopped raw meat & can maintain them for long periods. • Diets based on canned dog or cat food with vitamin K and some fruits added. • To adapt newly captured to laboratory diet, give no food for 2 days & offer laboratory diet as a soupy mixture in place of drinking water. • will drink this to obtain the moisture

Additional Reading Anderson, R.S. and Edney, A.T.B. Practical Animal Handling. Pergamon Press, Oxford, UK. 1991. Fowler, M.E. Restraint and Handling of Wild and Domestic Animals. Iowa State University Press. Ames, IA. 1995. Fowler, M.E. Zoo and Wild Animal Medicine. W.B. Saunders Company, Philadelphia, PA. 1986. Fox, J.G. Biology and Diseases of the Ferret. Lea and Febiger. 1988. Frye, F.L. Biomedical and Surgical Aspects of Captive Reptile Husbandry. Veterinary Medicine Publishing Company, Edwardsville, KS. 1981.

Additional Reading Hrapkiewicz, Karen, Leticia Medina, and Donald D. Holmes. Clinical Laboratory Animal Medicine: An Introduction, 2nd Ed. Iowa State University Press, Ames, IA. 1997. Johnson-Delaney, K. Exotic Companion Medicine Handbook for Veterinarians. Wingers Publishing. 1996. Kuehl-Kovarik, C. “The Gray Short-tailed Opossum: A Novel Model for Mammalian Development.” Lab Animal 24 (6) 1995. May, E.B., Bennett, R.O., and Reimschuessel, R. “The Application of Laboratory Technology to Fish as Models in Biomedical Research.” Lab Animal, May/June, 1987.

Chapter Twenty-Nine