The ferret (Mustela putorius furo) is a domestic pet. It is not a wild animal, though ferrets are descendants of the European polecat (weasel) and are, therefore, close relatives of skunks, mink, otters and badgers.
Types and Terms
There are 2 varieties of ferrets, based on coloration. Fitch ferrets (the most popular) are buff-colored, with black masks, feet and tails. Albino ferrets are white, with pink eyes. The female ferret is called a ‘jill’, while the male is called a ‘hob’. Babies are ‘kits’.
The gestation period of ferrets is 42-44 days (average, 42 days). The average litter size is 8 (range, 2-17). Kits are born deaf, with their eyes closed. Their eyes open and they begin to hear between 3 and 5 weeks of age. Their deciduous (‘temporary’) teeth begin to erupt at 2 weeks of age, at which time they begin to cat solid food. Kits generally are weaned onto commercial kitten chow at 4-8 weeks of age. Kits reach their adult weight at 4 months of age. Males are typically twice the size of females, but both sexes undergo periodic weight fluctuations. It is not uncommon for the average ferret to add 30-40% of its body weight in fat deposited beneath the skin in the fall, and lose this fat the following spring. The average lifespan of ferrets is 9-10 years.
Ferrets make wonderful pets because of their engaging personalities, playful activity and fastidious nature. They can be easily trained to use a litter box because they tend to habitually urinate and defecate in the same places. Provide a low-sided litter box for easy entry and exit. More than one litter box may be necessary if the ferret has free run of the house. There is no innate animosity between ferrets and dogs and cats, and all can usually share a household with little difficulty. However, ferrets have been known to attack pet birds, so it is advisable for owners of both to take appropriate precautions to prevent these encounters. Ferrets are naturally inquisitive and can squeeze through very small spaces. It is important to ‘ferret proof’ your house before bringing your pet home. Thoroughly check every room it will inhabit, sealing all holes and openings wider than 1 inch in diameter. Make sure that any windows that may be opened have secure screens. Check the openings around plumbing, heating and air conditioning ducts or pipes.
Some kits are small enough to squeeze under some doors. Ferrets are so small and silent that you will usually not hear them approach. They are easily stepped on when they are sleeping under a throw rug or suddenly turn up under foot. Their love of tunneling and their inherent curiosity frequently places them in potentially dangerous situations. They could very easily crawl unnoticed into your refrigerator, into the bottom broiler of a stove, through the rungs of a balcony railing, out the front door, or even end up in the washing machine with clothes under which the ferret was sleeping. Other dangers include folding sofa beds and reclining chairs. The obvious solution to avoiding accident and injury is to learn your ferret’s habits and be constantly vigilant.
To help protect your ferret, especially if it is allowed free run of the house, obtain an adjustable, lightweight cat collar, the kind with elastic on one end, a small bell, and an I.D. tag. The bell will signal that your ferret is underfoot or has perhaps slipped out the front door. The bell also helps to warn caged birds that are allowed unrestricted freedom in the home that the pet ferret is nearby. Unfortunately, we have seen a number of cases of serious injury and death to pet birds caused by ferrets. The collar also indicates to unknowing neighbors (many people have no idea what a ferret is) that whatever it is, it must be someone’s pet.
While ferrets are not destructive to most household items (furniture, clothing, etc), some have a tendency to chew on soft rubber. This is especially dangerous because the pieces of tennis shoes, Barbie Doll toes, or other rubber items can become impacted in your ferret’s intestines. Ingested pieces of kitchen gloves or sponges with household chemicals can also threaten your ferret’s life if eaten. Latex rubber squeak toys should not be given to ferrets because they may swallow parts of them, causing intestinal obstruction.
All ferrets have an affinity for people. Some enjoy people more than others. The older a ferret is, the mellower it is likely to become. Young kits tend to be nippy, but no more than a new kitten or puppy. They just nip with more enthusiasm. Some kits never nip at all, but most that do eventually outgrow it. Ferrets have tough skin and kits have sharp little teeth. The roughhousing a kit may do with its littermates may not be appropriate for its owner’s finger. Many new ferret owners mistake this nippiness for viciousness, even though the same behavior in a new kitten or puppy is accepted.
There are a number of documented cases of ferret attacks on infants and very small children. Some of these involved serious injury to the child. Parents must either forbid encounters between pet ferrets and their infants or very young children, or closely supervise all of these encounters. It is important to point out, however, that these unfortunate encounters are far less common than those involving household dogs and cats.
Ferrets are unusual animals, but not ‘exotic’. They have been domesticated for thousands of years and can be treated under the same set of disciplinary rules you would use for any other domesticated animal. Ferrets are extremely intelligent and can quickly be taught what they may and may not do.
Feeding commercial cat food can easily satisfy the dietary requirements of ferrets. The growth formulas for brand name cat foods, composed of high-quality meat (not plant) protein are preferred (for example, lams or Science Diet). Dry kibble is recommended over semi-moist and canned foods because the soft foods lead to disease of the gums and tooth roots. Table food also can be offered but should be limited to cooked meat, fish and poultry. Fruits and vegetables may be offered in very limited quantities. Do not feed milk and foods rich in sugars (cookies, candy) and carbohydrates (pasta, rice, bread) because ferrets have great difficulty digesting these foods. Bones and foods containing bones should not be offered because they are likely to injure the ferret’s digestive tract.
It is not necessary to offer vitamins or vitamin-mineral supplements to your ferret as long as it is fed as outlined above. Your veterinarian may recommend these dietary supplements, however, under special circumstances or for aged ferrets.
Fresh, clean water should be available at all times. Water bottles or heavy ceramic (crock) dishes can be used for this purpose.
Ferrets must be confined within the home and when their activities cannot be adequately supervised. Most ferrets prefer to sleep within a relatively small, enclosed area. A cat or rabbitsized wire cage or a suitably sized dog/cat airline carrier works very well. Wood shavings or a few towels can be used on the bottom of the enclosure. Ferrets are especially fond of tunneling under towels and prefer to sleep in this manner.
The objectionable odor of pet ferrets is primarily the result of the influence of sex hormones on normal skin secretions. Consequently, castrating male and spaying female ferrets is usually sufficient to control this problem. It is usually done at 6-8 months of age. Castrating male ferrets also helps reduce any aggressive tendencies. A very pungent and equally objectionable secretion occasionally is produced by the ferret’s scent (anal) glands. Some owners also have their pet ferrets descented.
When awake, ferrets generally exhibit constant activity. They can be easily picked up, however, and gently restrained by using both hands to support their weight and provide security from falling and injury. Ferrets can also be easily restrained for examination, laboratory sample collection, and treatment by gently suspending them off their feet by the nape of the neck. The relaxation that results from this method is similar to that exhibited by very young mammals as they are carried in their mother’s mouth from one place to another.
Two medical conditions of ferrets demand special mention: the ferret’s extreme susceptibility to canine distemper and the unusual consequences of female ferrets coming into heat. Other medical conditions are also briefly discussed below.
Ferrets are highly susceptible to canine distemper. The initial signs of the disease appear 7-10 days after exposure to the virus and include inappetence and a thick mucus and pus-laden discharge from the eyes and nostrils. A rash commonly appears under the chin and in the groin area 10-12 days following exposure. The footpads become greatly thickened. This disease is considered 100% fatal, with infected ferrets dying 3-3.5 weeks after initial exposure. Prevention of this disease should be an absolute priority because treatment is useless. Kits should first be vaccinated against canine distemper at 6-8 weeks of age (4-6 weeks of age if kits are from unvaccinated mothers). A booster vaccination is essential 2-3 weeks later. Yearly boosters are recommended thereafter.
Female ferrets are seasonally polyoestrus, which means they can come into heat more than once during the breeding season (March through August). They are also induced ovulators, which means ovulation occurs after copulation. The onset of heat is recognized by swelling of the external genitalia. If a ferret in heat does not engage in copulation, she will remain in heat for up to 160 days. If she is bred, the swelling of the external genitalia usually regresses to normal within 2-3 weeks after copulation.
Sustained sexual heat is dangerous and life-threatening because it usually results in bone marrow suppression. This results in severe anemia and decreases in the number of circulating white blood cells. Because of this likelihood, any female ferret not intended for breeding should be sterilized (spayed or ovariohysterectomized) at 6-8 months of age. We now recommend contraceptive implants which last several years and also prevent other diseases which are associated with sterilization of ferrets. This implant is also recommended in Male ferrets.
Researchers claim that ferrets are not susceptible to feline distemper. There are, however, reliable reports to the contrary. Consequently, the decision to vaccinate ferrets against this disease is an option for each ferret owner. However, if an individual ferret is likely to have substantial contact with cats (especially those of unknown or uncertain health status), vaccination of the ferret against feline distemper is a wise idea. The vaccine itself cannot harm the animal, and it represents ‘insurance’. The vaccination schedule for feline distemper is the same as for canine distemper.
Ferrets are assumed to be highly susceptible to rabies and capable of transmitting the virus (not UK). Vaccination trials using standard rabies vaccines have never been carried out to determine the protective value of such vaccines. Consequently, it is not known if the vaccines currently being given are protective, and if so, for how long. In spite of these facts, a killed rabies vaccine should be given annually, starting at 3 months of age. Of course, there is a danger that such a vaccine may produce a false sense of security. Nevertheless, it is unlikely that an average domestic ferret, living in an urban household, will come into contact with rabies virus by way of a bite or contact with the saliva of a rabid animal.
Other Viral Diseases>
Ferrets are not susceptible to the viruses that commonly produce upper respiratory disease in domestic cats (rhinotracheitis, calicivirus), nor are they susceptible to canine hepatitis. There is no definitive evidence that ferrets are susceptible to canine parvovirus or feline leukemia virus; therefore, vaccination against these diseases is probably unnecessary. A few cases of lymphoma and lymphosarcoma (cancer) have occurred in ferrets over the years. Some of these ferrets tested positive for feline leukemia virus, while others tested negative. Though a cause-and-effect relationship cannot be proven by such a small number of cases, the possibility exists that ferrets may become infected with feline leukemia virus. Cancer can be one possible result of such an infection. Some researchers believe that leukemia and related diseases among ferrets may be caused by a virus or viruses specific to ferrets.
Feline Infectious Peritonitis This is another serious viral disease of cats for which ferret susceptibility is not yet known. There is no vaccine available for this disease, not even for cats. Because of the lack of knowledge regarding ferret susceptibility to this disease and the other feline diseases previously discussed, ferret owners should be extremely cautious with regard to their pet’s exposure to cats, especially those exhibiting signs of illness and those of unknown health status.
Influenza It is interesting to note that ferrets are susceptible to infection with several strains of human influenza (‘flu’) virus. Signs of this illness may mimic those of canine distemper (listlessness, fever, inappetence, sneezing & nasal discharge, etc). Unlike distemper, however, influenza usually passes within 5 days of the onset of illness, and ferrets recover. Bacterial infections may complicate the viral infection.
Parasitism Most of the external parasites of domestic dogs and cats (fleas, mange mites, car mites, etc) can cause disease in ferrets. Less is known about the ferrets’ susceptibility to the more common internal parasites (roundworms, etc) of dogs and cats. Protozoan (one-celled) parasites, also shared by dogs and cats (especially giardia and coccidia), can cause intestinal disease among ferrets. Periodic faecal (stool) examinations should be performed by your veterinarian to check for such parasites. Appropriate treatment can then be given, if warranted.
Ringworm Ringworm (a fungal disease of the skin similar to athlete’s foot) has been reported in young ferrets and may be transmitted by infected cats. As a rule of thumb, products manufactured and intended for use in and on cats (dewormers, flea products, ringworm medications, etc) are safe and suitable for use in and on ferrets, with one exception: flea collars should never be used on ferrets.
Heartworm Disease Ferrets are susceptible to heartworm disease, a mosquito-transmitted illness seen primarily in dogs (not UK). Ferret owners must carefully consider the pros and cons of preventive therapy for this disease. Some ferrets may have adverse reactions to the drug used for heartworm prevention. Furthermore, the average pet ferret is very unlikely to be bitten by an infected mosquito unless it lives in an area of heavy heartworm infection and is often exposed (housed outdoors) to mosquitoes. Most pet ferrets housed exclusively indoors are unlikely to become infected by heartworms and should not require preventive therapy.
Bacterial Infections Various bacteria can produce a variety of diseases in ferrets, including botulism, tuberculosis, dysentery (caused by Campylobacter fetus), and abscesses and infections caused by bite wounds and other injuries. Judicious use of antibiotics is usually sufficient for treatment of most, but not all, of these conditions.
Heat Stroke Ferrets lack sweat glands and are somewhat compromised in their ability to maintain normal body temperature in extremely warm environmental temperatures. If the temperature rises above 90°F, and if water is restricted or not available to ferrets, heat prostration is likely and death quite possible. Providing ample shade and spraying your ferret on hot days will help reduce the likelihood of this problem.
Urinary Stones Urinary stones, either within the kidneys or urinary bladder, may cause serious problems in ferrets. Both sexes seem to be affected equally. Signs of urinary stones include blood in the urine, inability to urinate, a swollen and painful abdomen, vomiting, listlessness and inappetence. Surgery is usually necessary to correct this problem, though a special diet may eliminate certain types of stones or prevent recurrence.
Cardiomyopathy Cardiomyopathy is a condition of the heart muscle seen in dogs, cats and ferrets. Most affected ferrets are males over 3 years of age. The cause for this condition is unknown. The muscle walls of the heart become thickened, reducing the ability of the heart to pump adequate quantities of blood to the rest of the body. Signs include inappetence, fatigue, increased periods of sleep, intolerance to exercise, fainting and shortness of breath. Cardiomyopathy is diagnosed using chest x-rays, an electrocardiogram (ECG) and echocardiography (a diagnostic technique using ultrasound waves). All ferrets older than 3 years should have an ECG to screen for this disease.
Insulin-secreting tumors are not rare among ferrets. These tumors cause persistently low blood sugar levels, which produce weakness, depression, fainting spells, changes in behavior and convulsions.
A number of Autoimmune diseases of ferrets have been identified. These types of diseases arise when the ferret’s immune system begins to destroy one or more of the body’s components. These diseases are usually very serious. Signs may include depression, lethargy and weakness. Veterinarians experienced in working with companion exotic animals should be consulted if this type of disease is suspected. An evaluation of the blood (and perhaps other tissues) is necessary to diagnose autoimmune disease.
Cataracts are fairly common in pet ferrets (young and old). Their significance and genetic predisposition are not fully understood.
Ferrets’ nails (claws) can become extremely sharp and should be trimmed periodically. The method used and guidelines followed are identical to those used in trimming the nails of a dog or a cat. Ferrets should not be declawed.
For More Information below are the names and addresses of organizations and publications dedicated to ferrets:
•California Domestic Ferret Association, PO Box 1868 Healdsburg, CA 95448 (707) 431-2277
•Central Illinois Friends of Ferrets, PO Box.564 Urbana, IL 61801
•Ferret (journal for veterinarians) 1014 Williamson St, Madison, WI 53703 Ferret Fancier’s Club, 713 Chautauqua Court Pittsburgh, PA 15214
•Greater Chicago Ferret Association, PO Box 7093 Westchester, IL 60153 (312) 357-8682
•International Ferret Association, PO Box 522 Roanoke, VA 2,4003