II. Dermatophytosis
III. Rabies
IV. Salmonellosis
V. Tuberculosis
Infestation with Sarcoptes scabei may take two forms: 1) a focal
to generalized alopecia and intense pruritus associated with the mite,
which can be found in skin scraping of affected areas, or 2) sarcoptic
lesions which are confined to the toes and feet where feet are swollen,
scabby, and if not treated, clawless. Diagnosis is made by scraping
affected areas and observing the typical sarcoptid mite (see photo).
Treatment consists of application of sulfur ointment or lime and sulfur dips and washes, and trimming the claws and removing the scabs after softening them in warm water. Other topical treatments used for dogs have been used successfully on ferrets. Ivermectin is probably the most successful treatment available and has been successfully used to treat Sacroptes in ferrets (0.2mg/kg repeated in 2 weeks). Pruritus may be reduced by administration of corticosteroids.
Ferrets may also be infected with fleas (Ctenocephalides sp.) and may be treated with mild flea products, similar to those used on cats. Ear mites (Otodectes cynotis) may be treated with ivermectin (0.2mg/kg) repeated in 2-3 weeks.
Public Health Significance: Humans may be bitten by fleas and become infected with Sarcoptes
scabei, which manifests as pruritis beginning in the areas of the skin
having contact with the animal. The skin frequently becomes encrusted and
excoriated as the disease progresses.
Ringworm (Microsporum canis and Trichophyton mentagrophytes)
has been reported in young ferrets. Stored litter or shavings for
nest boxes are often the source of infection. The lesions are similar
to those described for cats. There are circumscribed areas of alopecia
and scaley crusts spread all over the body. Topical fungicides and
time will clear up the crusty, hairless lesions while fresh nest box material
will help prevent recrudescence. Griseofulvin (25 mg/kg ) may also
be used with topical therapy in advanced cases. 
Public Health Significance: Humans are susceptible to dermatophyte
infections.
Ferrets are susceptible to rabies virus, but the latency or duration of spontaneous infection is unknown. Rabies has been diagnosed in 6 ferrets since 1980, and in one case the ferret might have been vaccinated with a modified live rabies vaccine. Another case of ferret rabies was diagnosed in a ferret with no history of vaccination or exposure to a wild carnivore. There are now several USDA-approved killed vaccine products for use in ferrets: Imrab3, Rhone Merieux, Inc. and Prorab 1, Intervet. The dose and schedule for ferret vaccination is the same as that for cats, and the vaccine is effective in protecting ferrets from live virus challenge. However, the Public Health Service, through the CDC, currently recommends that vaccinated ferrets that bite a human should be euthanatized for rabies examination. The 10-day postbite quarantine is not known to be adequate for ferrets, and cannot be used as a standard until enough clinical data is collected from vaccinated ferrets. When faced with such a bite case, it may be best to contact the state public health official for the latest recommendations. Decreasing the risk of exposure to wild carnivores markedly decreases the chance of ferrets contracting the disease. There are other conditions that can cause central nervous system diseases in ferrets, particularly canine distemper virus infection. If there is any doubt as to the progression of a CNS disorder in a ferret, the affected ferret should be isolated and or euthanatized so the brain can be submitted for laboratory examination of rabies virus infection.
Public Health Significance: The concern of humans contracting rabies from unvaccinated pet ferrets is one of the major issues that precipitated the passage of laws and ordinances preventing private ownership of ferrets in many cities and states.
Ferrets do not appear to be highly susceptible to salmonellosis. Salmonella enterica serovar Typhimurium has been isolated from ferrets with severe conjunctivitis, dysentery, rapid weight loss, and a fluctuating body temperature. Serovars Tyhpimurium and Cholerae-suis have all been associated with clinical disease including abortion in pregnant ferrets. Macroscopic postmortem findings include gastroenteritis, with splenic and hepatic necrosis. Diagnosis should be confirmed by isolation of the organism from the feces. Oral sulfathiadine (1 gm/kg body weight once daily) for 4 to 7 days has decreased the clinical disease signs and reduced the shedding in experimentally-infected ferrets; however, the risks of medicating infected ferret needs to be weighed against the risk of exposing humans or other animals to Salmonella.
Public Health Significance: The risk of human infections should always be considered when investigating ferrets with dysentery.
Avian, bovine, and human strains of mycobacteria can cause tuberculosis in ferrets, however clinical disease is uncommon. Clinically, infected ferrets may become emaciated and exhibit paralysis of the adductor muscles of the hind limbs which may progress to affect all limbs. Disseminated disease caused by M. bovis is associated with weight loss, inappetance, lethargy, progressive muscle paralysis, hepatosplenomegaly, and death. Enlarged mesenteric lymph nodes may be palpated. At necropsy the adductor muscles appear yellow and soft. Multifocal areas of coagulative necrosis throughout the gastrointestinal tract, hepatosplenomegaly, and mesenteric lymphadenopathy may be found. Histologically, massive accumulations of histiocytes containing acid-fast bacilli may be found in abdominal organs. Other diseases that cause posterior paralysis include hemivertebrae, vertebral fractures, intervertebral disc disease, hematomyelia, or myelitis. A thermal response to the intradermal tuberculin tests using mammalian tuberculin (not PPD), use of radiology (to look for calcified lymph nodes), and lymph node or splenic biopsy with acid-fast staining aid in diagnosis of tuberculosis. There is no recommended treatment for tuberculosis in ferrets. Euthanasia is recommended.
Public Health Significance: Ferrets are susceptible to same forms of
tuberculosis as humans and may be potential sources of human infection.
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