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.

Canine Distemper
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 tick 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 foot pads become greatly thickened. This disease is considered 100% fatal, with infected ferrets dying 3-3 1/2 weeks after initial exposure.

Prevention of this disease should be an absolute priority because treatment is useless. Kits should fist be vaccinated against canine distemper at 68 weeks of age (4-5 weeks of age if kits are from unvaccinated mothers). A booster vaccination is essential 2-3 weeks later. Yearly boosters are recommended thereafter.

Heat Periods
Female ferrets are seasonally polyestrus, 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 spayed at 6-8 months of age. Female ferrets in heat can be taken out of heat within about 3 weeks by injection of a specific hormone after the first 10 days of heat. Once out of heat, they can be spayed before they come back into heat (usually 40-50 days after administration of the hormone).

Feline Distemper
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. Most veterinarians administer a combination canine distemper-feline distemper vaccine.

Rabies
Ferrets are highly susceptible to rabies and can transmit the virus. A rabies vaccine is now available for use in ferrets. Ferrets 3 months of age or older should be vaccinated, with annual boosters thereafter. Owners of vaccinated ferrets should know, however, that under certain circumstances, public health authorities may require euthanasia of vaccinated ferrets that have bitten a person.

Other Diseases
Ferrets are not susceptible to viruses that commonly produce upper respiratory disease in domestic cats, nor are they susceptible to canine hepatitis. These is no definitive evidence that ferrets are susceptible to canine Parvo-virus or feline leukemia virus; therefore, vaccination against these diseases is probably unnecessary. A few cases of lymphoma and lymphosarcoma (cancer have occurred in ferrets. 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 an infection. Some researchers believe that leukemia and related diseases among ferrets may be caused by a virus or viruses specific to ferrets.

Influenza: It is interesting to note that ferrets are susceptible to infection with several strains of human influenza 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. Treatment with a specific anti-influenza-A drug may be recommended. Such treatment is not recommended if bacterial infection complicates the influenza infection.

Parasitism: Most of the external parasites of domestic dogs and cats (fleas, mange mites, ear mites, etc.) can cause disease in ferrets. Less is known about the ferret's susceptibility to the more common internal parasites (roundworms, etc.) of dogs and cats. Protozoan parasites, also shared by dogs and cats (especially Giardia and Coccidia), can cause intestinal disease among ferrets. Periodic fecal 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 BY USED ON FERRETS.

Heartworm Disease: Ferrets are susceptible to Heartworm disease, a mosquito-transmitted illness seen mostly in dogs. 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. Further, the average 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 to mosquitoes.

Bacterial Infections: Various bacteria can produce a variety of diseases in ferrets, including botulism, tuberculosis, dysentery 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, and electrocardiogram (EKG), and echocardiography. All ferrets older than 3 years should have an EKG to screen for this disease.

Miscellaneous Problems: Tumors cause persistently low blood sugar levels, which produce weakness, depression, fainting spell, 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 cam 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.