Anatomy

Ferrets have long bodies with short legs, allowing them to get into and out of tight tubular spaces. Their spine is very flexible. Male ferrets are usually about twice the size of female ferrets. Ferrets are monogastric animals whose organ arrangement is similar to that of the cat. The coat of the ferret is soft and exists in many color variations (at least 30 colors are recognized). They molt in the spring and fall as their weight changes (increase in the fall and decrease in the summer). Molting can be related to season and to ovulation. The skin should have a smooth appearance. Ferrets have no sweat glands, but they do have active sebaceous glands that produce the characteristic body odor. Ferrets have well-developed anal glands that produce a serous yellow liquid with a powerful odor. As with skunks, ferrets that are threatened or frightened may expel the contents of these glands over a long distance (and usually the technician or veterinarian treating them). Removal of these glands (descenting) will help alleviate much, but not all, of the odor of the ferret.

Ferrets have good special senses and can see well in low light. They have nonretractable claws that need to be trimmed periodically. All the other organ systems are similar to those of the cat.

Behavior

Ferrets are predators, and even today their behavior mimics that of their ancestors. They are able to live in communal groups and to interact well with humans. They engage in play, territory marking, and hunting behaviors throughout life. Play can become aggressive if not curtailed. Ferrets may scream, a noise that is quite loud and disturbing, when playing. They also love to burrow in soft materials, including carpet, furniture, and litter boxes. This can be quite destructive. They love to explore tunnel-like areas and prefer having an enclosed sleeping place. Ferrets can be taught to use a litter box, and they will never soil their sleeping quarters. They can also get into trouble by chewing on rubber items such as electric cords, toys, appliances, and rubber bands, causing intestinal upsets or obstructions. It is not uncommon for them to escape through small holes in the environment.

Housing

A ferret’s environment must be “ferret proofed” before the addition of a pet. Because most ferrets do not adapt well to continuous caging, the entire play area must be made safe. This usually means closing any small holes that might provide escape, removing all rubber objects, covering the bottom of all furniture pieces to prevent burrowing, and providing a secluded area for sleeping. Ferrets can be housed in wire or wooden cages if these provide adequate ventilation. If kept outdoors, they must be protected from the sun and excessive temperatures, because they have little ability to regulate their body temperatures and can become heat stressed. Toys for ferrets include boxes, bags, plastic pipes, sleeping bags, dryer vent tubing, and burrowing pits. Owners should avoid providing any toys that contain latex rubber. Ferrets will use a litter box, but the walls of the box should be high enough to catch the urine deposited when the ferret backs up to the corner. Pelleted litter usually works better than clay or clumping litter. It is suggested that owners provide several boxes placed around the house instead of one centrally located box.

Nutrition

Ferrets are strict carnivores designed to eat whole prey. Their digestive tracts cannot handle carbohydrates and fiber well. The most common diet for pet ferrets is dry kibble. The diet should contain 30% to 35% protein (high-quality meat source) and about 15% to 20% fat. Many prepared dog and cat chows contain too much carbohydrate and plant protein, which can lead to health problems. A limited amount of soft, fresh meat or eggs can be added to the dry diet if desired. Because ferrets love sweets and will develop dietary preferences early in life, owners should be discouraged from feeding fruits, raisins, or other sweet foods to their ferrets. All ferrets should have access to clean, fresh water at all times.

The Ferret as a Patient

Most pet ferrets are accustomed to being handled and will not present a problem to the veterinarian or clinic staff; however, one should always inquire about the animal’s temperament before the examination. Ferrets will bite without warning, unlike most dogs and cats. They may be scruffed by the loose skin on the neck and suspended with all four legs off the ground (Fig. 13-1), or they may be restrained much like a cat on the table for routine procedures. If the procedure might be painful (e.g., drawing blood), the ferret should be scruffed and held at the hips. All ferrets should be vaccinated against rabies and canine distemper (IMRAB 3 [Merial] and Fervac-D [United Vaccines] or PureVax [Merial]). Anaphylactic vaccine reactions are not uncommon in ferrets, especially from the distemper vaccine, and diphenhydramine, epinephrine, or corticosteroids should be used if a reaction occurs.

Figure 13-1 Restraint of a ferret by scruffing the loose skin on the back of the neck.

(From Quesenberry KE, Carpenter JW: Ferrets, rabbits, and rodents, ed 2, St Louis, 2004, Saunders, by permission.)

“Rodent Etiquette” or “How to Make Your Rodent Pets Feel at Home in Your Clinic”

Just like humans who do not get enough sleep, rodents can become irritable if they are disturbed during their normal hours of rest. Hamsters and rats are nocturnal and sleep during the day when most veterinary clinics see patients. Gerbils and mice can be active during both the day and night. By trying to schedule the patient’s appointment at a time they would normally be awake, the veterinary staff may find a happier patient, one that is less likely to bite or become aggressive.

Owners should be instructed to bring the animal to the clinic in its cage and not to clean the cage before the appointment. In this way the veterinarian can assess the care being provided to the pet and the environment in which the pet lives. Many times these clues can help to determine the problem.

It might be best to avoid making rodent appointments when the waiting room is filled with cats or other natural predators. Try to schedule them when the room will be quiet and calm. A checklist would be helpful to enable the technician or receptionist to get a complete medical history from the owner before being seen by the veterinarian. It is important to also obtain an accurate weight for all small patients, because it will be intricate in determining the dose of medication needed for treatment.

Rodents Commonly Kept as Pets

Rats and Mice

Mice, and especially domesticated rats, make good pets; however, they may produce severe allergic reactions in some people. Because of their resemblance to the wild pest species, many people shy away from handling rats and mice. These pets have a limited life span, which may present a problem for the owners. Rats may live 2 to 3 years and mice an even shorter time. The best diet for pet rats is a laboratory chow designed specifically for rats, together with limited amounts of grains, vegetables, and fruits. Owners typically overfeed rats on junk food, resulting in obese, obnoxious pets that beg for food. Rats can be housed in a variety of cages, some with condos and luxury furniture for the comfort of the occupant. Whatever type of cage is used, it must have good ventilation because rats urinate frequently and the ammonia build-up in poorly ventilated cages can affect the health of the animal. Rats respond well at normal room temperatures, but should not be left to roam the house unattended.