HUSBANDRY, HANDLING AND TREATMENT OF POCKET PETS

Lucy W. Bartlett DVM, Diplomate ABVP, Specialty of Avian Practice
Avian and Animal Hospital of Bardmoor
11405 Starkey Road
Largo, FL 33773

Guinea pigs and Chinchillas

Guinea pigs and Chinchillas are both rodents and are also similar in many respects anatomically and physiologically. They are both monogastric herbivores from South America. They have a large cecum and bear precocious young after a relatively long gestation period. Both creatures are lively but gentle, docile pets. They may occasionally be a little skittish but in general are not difficult to care for.

Guinea pigs require vitamin C in their diet because they can not produce it. Chinchillas do not need vitamin C supplementation. Chinchillas require daily dust baths unlike Guinea pigs but are not prone to dystocia as Guinea pigs are.

Guinea pigs come in three common types; English and American varieties, Peruvian (very long hair) and Abyssinian (short, course hair that grows in whorls). The color varieties include white, red, brown, black, tan, chocolate, and combinations of the above.

Guinea pig housing should be 2 square feet of floor space per pig. Newspaper, shredded paper, or straw can be used on the cage bottom. Ventilation should be good. Flooring can be solid or wire mesh (more foot problems with wire). They do not climb or jump, so cage tops are not always needed. They produce a lot of feces, often in their water and food dishes and are known to inject a premasticated slurry of pellets into the tubes or their sipper bottles causing a dangerous plug that can result in life threatening dehydration if not detected in time. They need a hide box and require cooler temperatures (65-79 degrees F).

Diets for Guinea pigs still need much researching but at this time the best recommendations include guinea pig pellets (vitamin C added), alfalfa or grass hay and fresh vegetables especially dark leafy greens. The vitamin C in pellets is only active for 90 days under ideal conditions so supplementation is recommended. There is Vit.C (ascorbic Acid) in kale, parsley, beet greens ,chicory, spinach, red and green pepper, broccoli, tomatoes, kiwi, and oranges. Provide some of these daily. Vitamin C can be added to the water at 1 gram/litter of drinking water and changed daily.

Guinea pigs and chinchillas perform coprophagy which means ingesting soft fecal cecal feces directly from the anus. This is an important function and is essential for proper nutrition and digestion. Animals that are prevented from coprophagy become ill.

When well taken care of, Guinea pigs have few disease problems. Once they become ill they must be treated early in order to recover. Sick pigs are very delicate and at times seem to just give up the will to live. They do not tolerate clinical procedures well and may go into respiratory or cardiac arrest when another species would not under similar circumstances. All handling must be careful and gentle with attention paid to providing good supportive care, maintaining caloric support, keeping the environment stress-free and slowly working towards a diagnosis and then specific treatment.

Chinchillas require more room than the pigs and multilevel cages. They love to climb and jump and need room to do so. Dust baths need to be provided daily. Sanitized chinchilla dust is commercially available in pet stores. Alternatively a 9:1 mixture of silver sand and Fuller's earth can be used. Beach sand is not suitable. Put one inch deep of dust in a low flat pan like a kitty litter pan and allow 20-60 minutes a day of "bathing" then remove the pan to prevent fecal contamination. Hide boxes are needed for security. Y and T sections of PVC plumbing pipes make good hiding spots and are easy to clean. They need a dry cool environment (ideally 50-68 degrees F). They are prone to heat stroke when the temperatures climb above 82-86 degrees F, therefore outside cages in will not be appropriate in the summer (or spring or fall) in Florida.

Not a lot is known about Chinchilla diets except the fact that they need high fiber. There are chinchilla pellets commercially available that are mixtures of rodent, guinea pig and rabbit chow in a slightly longer pellet. Nonbreeding chinchillas do well on good quality grass hay, a small amount of pellets, fresh vegetables and grains. Breeding and growing chinchillas need a richer diet provided by increasing the amount of pellets. Wood for gnawing can be provided and safe woods include elm, maple, birch and bark from apple, pear and peach trees,

Handling

When frightened, Guinea pigs will usually freeze their position and stay still, with only an occasionally attempt at bolting away. Keeping a hand on the rump will keep them from backing up when being examined. Carry a pig by supporting the body in one hand and cupping the dorsum with the other.

Chinchillas use flight as their defense mechanism. They can move very suddenly and can loose a patch of fur ("fur slip") when frightened and then grabbed. When lifting a chinchilla place one hand under the body or around the neck and hold it by the base of the tail with the other hand. They can also loose the skin on the tail if grasped too far down from the base. They will leap and jump with little encouragement so stay alert. When carrying a chinchilla, tuck the head under your arm.

Try to take the rectal temperature before the animal becomes too excited. Check the nail and clip if needed. Venipuncture can be difficult in these species. The lateral saphenous and cephalic veins are very small. Clipping the hair and using a small needle for example a 25 to 27 gauge is beneficial. The jugular vein can be used but the restraint needed may be too stressful on sick animals of this type. Stop immediately if stress or dyspnea becomes apparent.

Supplemental fluids are usually given subcutaneously into the loose skin over the shoulders. Normal daily water intake in the Guinea pig is 100ml/kg. Volumes of 25-35 ml can be given at a time with the total daily volume divided in to 3 doses. IV catheters may be used but often the stress of placement out weights the benefits. The same is true for the chinchilla.

Injections can be given SQ over the shoulders where the skin is often very thick, use a 25 gauge needle. IM injections can be given in the gluteal or biceps muscles. Medications and oral nutritional supplementation is given with a syringe into the side of the mouth. Force feeding guinea pigs and chinchillas that are anorectic is very important and easily accomplished with a curved tip 12 cc syringe and vegetable baby food, a slurry made up of their pellets, Nutrical (Evasco Pharmaceuticals, Buena, NJ), a soy based liquid enteral formula or combinations of the above. Add Vitamin C to all guinea pig formulas.

Guinea pigs do not adapt well to changes in diet or surroundings. They often become more depressed and will not eat when hospitalized if the food is slightly different or the surroundings are unfamiliar. Whenever possible, keep hospitalization to a minimum and teach owners how to do nursing care and treatment at home.

Mice, Rats, Hamsters and Gerbils

Clients that bring their rodents into the veterinarian are in most cases bonded to their pet and need to feel the hospital staff is compassionate and knowledgeable. Pet rodent owners will often request the same level of care and diagnostics as a dog or cat owner and such care should be available and offered.

When scheduling appointments, keep in mind that the hamsters and rats are nocturnal in nature and are better evaluated late afternoon. Mice and gerbils are active day and night so scheduling is not as important. Have clients bring the rodent in his own cage so the cleanliness, food, water supply and general habitat can be evaluated. Tactfully request that the clients not clean the cage just before bringing it in. Cages should be well ventilated, large enough to allow exercising and include hiding places.

When getting a history from the owners, inquire about the temperature where the animal is kept. Rodents usually suffer more from overheating than from being too chilly.

Note the type of substrate in the cage, aromatic types of wood chips like cedar are at times irritating to the rodent.

Where the animal came from, how long the owners have had it and has it been exposed to other rodents are all pertinent questions.

Small rodents should be fed a complete, fresh, wholesome, palatable, clean, pelleted rodent diet with a protein above 14%. Supplementation with small amounts of fresh vegetables is acceptable.

Fresh water from a clean sipper bottle should always be available.

Vitamin drops, salt blocks, seeds and various treats are usually not necessary.

Pellets that are not fresh loose the nutritive value and will lead to malnutrition. Owners need to find a source that orders fresh food frequently so they are not buying pellets that have been stored or on the shelf for months.

Handling Rats, Mice and Hamsters

Pets that have been frequently and gently handled often need little restraint for the physical exam. Other rodents will need to be restrained in a towel or even heavy gloves are needed at times. Though pet rodents do not often bite, when they do it is relatively painful and one needs to resist the "fling against the wall" reflex. Usually a difficult rodent can be grasped behind the head with the thumb and fore finger and the body can rest in the palm of the same hand. It may be easier to first throw a thin towel over the creature and then grab with confidence. The value and safety of taking a rectal temperature is questionable in small rodents, but getting an accurate gram weight is essential.

Small amounts of blood can be obtained from a hind-end skin stab, nail clip or nick of the tail tip. When enough blood is needed for a CBC or biochemical analysis it can occasionally be drawn from the saphenous or dorsal metatarsal vein if visible. This is not always possible in a small rodent because of the quantity and quality of blood needed. Isoflurane gas anesthesia through a mask will allow venipuncture in some patients that can not be easily handled awake.

Most illnesses in pet rodents are related to their skin, digestive tract and respiratory tract. Fecal exams, fungal cultures and skin scrapings can be performed as you would any other mammal.

Hamsters have distensible cheek pouches and pigmented sebaceous flank pouches that clients mistake occasionally for lesions. Bacterial pneumonia caused by Streptococcus species may be inadvertently transmitted to hamsters by children. Rapid diagnosis can be made by identifying the characteristic gram positive diplococci on a Gram's stain of nasal or ocular discharge. Female hamsters have a normal post-ovulatory discharge at the end of their estrus cycle. It is a stringy, creamy, white discharge and may be mistaken for pus by the owners.

Handling Gerbils

Grasping gerbils too far down on the tail can lead to "tail slip" where the skin of the tail comes off in your hand. The remaining raw exposed tail will usually become necrotic and shed if not amputated. Make sure you only gently grasp the base of the tail when tail grabbing is necessary. Gerbils have large ventral abdominal marking glands that are androgen dependent. These glands can become infected with age or neoplastic. A genetic based seizure disorder has been described in 20-40% of young gerbils. The seizures may be mild or severe and are out grown with time in some cases.

Antibiotics

There are many antibiotic sensitivities in rodents. Proper antibiotic choice and proper dosing is essential. Streptomycin and procain are toxic to mice. Nitrofurantoin causes neuropathologic lesions in rats. Gerbils can not tolerate dihydrostreptomycin and streptomycin. Avoid penicillins, erythromycin and lincomycin in Hamsters and Guinea pigs.

Antibiotics that have been used in rodents with apparent safety include enrofloxacin, ciprofloxacin, trimethoprim-sulfa and chloramphenicol. Dilution maybe needed for accurate dosing and using tuberculin syringes will help in administering the proper dose. Antibiotics in the water may the only way to treat some rodents but dosing will be inaccurate and some rodents will refuse to drink.

Anesthesia

Anesthesia in all the pocket pets with few exceptions should involved isoflurane gas (Errane).

There is no other anesthetic gas that demonstrates such a rapid induction and recovery and is as safe for both patient and hospital personnel. Mask induction is quick and intubation is recommended when possible though the size of many small rodents makes this impossible. A nonrebreathing system should be used for anesthetic delivery.

Rats, mice and gerbils do not vomit. They have a high metabolic rate and small size requiring frequent feeding and for these reasons, fasting is not recommended.

Chinchillas and Guinea pigs should be fasted 2-4 hours prior to anesthesia but do not with hold water.

REFERENCES

Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery, Elizabeth V. Hillyer, DVM and Katherine E. Quesenberry, DVM
W.B. Saunders Company, 1997

The Biology and Medicine of Rabbits and Rodents (3rd. ed.), John E. Harkness, DVM and Joseph E. Wagner, DVM, Lea & Febiger, 1989

The Veterinary Clinics of North America Small Animal Practice, Exotic Pet Medicine II, Katherine E. Quesenberry, DVM and Elizabeth V. Hillyer, DVM, W. B. Saunders Company, 1994

Chinchillas, A Complete Owners Manual, Maike Roder-Thiede, Barron's Educational Series, 1993

Exotic Companion Medicine Handbook for Veterinarians, Cathy A. Johnson-Delaney, DVM, Wingers Publishing, Lake Worth, FL