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 in the general, parasitic and infections diseases pages.
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 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 foot pads become greatly thickened. This disease is considered 100% fatal, with infected ferrets dying approximately 3 1/2 weeks after initial exposure. Prevention of this disease should be an absolute priority because treat:mentis 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.
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 sterilized (spayed or ovariohysterectomized) 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.