|
Distemper: |
| Foxes are susceptible to canine distemper virus (
Canine Distemper: Introduction), which is easily transmitted between dogs, mink, ferrets, raccoons, and other susceptible species. Because of the high population density in confinement and the high transmissibility of the virus, mortality on unvaccinated farms may be 50% in breeding stock and 75% in pups. The diagnosis is based on clinical signs, histologic lesions (including the presence of inclusion bodies), ELISA,
immunohistochemistry, and fluorescent antibody procedures. The most effective control procedure during an outbreak is to immediately destroy all foxes showing signs of disease and to vaccinate all others. All dead animals should be incinerated, and all equipment thoroughly disinfected. Because there are no licensed distemper vaccines for foxes, mink vaccine has been used. Vaccination of weaned pups at 12-13 wk of age is suggested. Annual vaccination of breeder foxes is
recommended. |
|  |
|
Fox Encephalitis: |
| This disease, caused by the same virus that causes infectious canine hepatitis (
Infectious Canine Hepatitis: Introduction), may cause serious losses when unvaccinated foxes are raised intensively. Mortality may be 2-40% on affected ranches. Fox encephalitis has a rapid course. The virus invades cells in the liver and kidneys and the endothelial lining of small blood vessels. Signs include anorexia, bloody diarrhea, depression, and often nervous signs such as convulsions and paralysis.
Death occurs in a few hours to a few days. Signs and death are due to hemorrhage of small vessels throughout the body, including the brain. Diagnosis is confirmed by demonstrating typical intranuclear inclusion bodies in liver, kidney, and endothelial cells; virus isolation; or fluorescent antibody techniques. An inactivated vaccine is available. Pups from unvaccinated vixens are vaccinated at weaning, and others when 10-12 wk old. Breeders should be given booster vaccinations in
December or January. |
| |
|
Salmon Poisoning: |
|
Neorickettsia
helminthoeca
is the cause of salmon poisoning disease (
Salmon Poisoning Disease and Elokomin Fluke Fever), which is the result of eating salmon or trout that harbor the vector fluke,
Nanophyetus
salmincola
. Signs include fever, inappetence, vomiting, lethargy, and diarrhea. Treatment is the same as for dogs. Untreated foxes usually die. |
| |
|
Botulism: |
| Improper handling and storage of food is the usual source of botulism in foxes as well as in mink. Storage of meat byproducts in metal drums, in which anaerobic conditions prevail, is an excellent medium for production of botulism toxin. In almost all instances, type C toxin has been incriminated. Signs include flaccid paralysis and abdominal breathing, usually followed by death. Because vaccines approved for foxes are not available, those approved for mink are used.
(See also
botulism,
Botulism.) |
| |
|
Canine Parvovirus: |
| While canids in zoological parks have succumbed to canine parvoviral infection, there have been no reported outbreaks of canine parvovirus (
Canine Parvovirus) on commercial fox farms; however, the prospect of an outbreak should be kept in mind. Vaccination of silver foxes with inactivated canine parvovirus vaccines should be considered, whereas blue foxes might be better protected with mink virus enteritis vaccines. |
| |
|
Parasites: |
| Internal and external parasites are controlled by means essentially the same as those recommended for dogs. |
|
Fleas (
Ctenocephalides
canis
) cause skin irritation and sometimes severe anemia and are particularly harmful in pups.
Ear mites (
Otodectes
cynotis
) are common in ranch-raised foxes. Infected foxes shake their heads and dig at the base of the ears with their front paws. Secondary bacterial or mycotic otitis may result. Some foxes hold their heads to one side. (See also
fleas,
Fleas and Flea Allergy Dermatitis: Introduction, and otitis externa,
Otitis Externa: Introduction.) |
|
Sarcoptic mange (
Sarcoptes
scabiei
) may cause serious economic loss in ranch-raised foxes. Clinical signs are similar to those seen in dogs. Ivermectin at 200 µg/kg, SC, has been used successfully to treat outbreaks; however, idiosyncratic reactions have been reported in some dogs at this dosage, and caution is suggested. (See also
Mange in Dogs and Cats.) |
|
Hookworms (
Uncinaria
stenocephala
) in commercially raised foxes can cause deaths in pups. Fox pups are infected by larvae in the vixen’s milk. Anemia may be profound, and pups may die beginning at 12 days of age. Fecal samples from these pups often are negative for eggs, and death may occur before the infection becomes patent. Pups with milder infection may grow poorly, appear emaciated, and have a marginal anemia. Treatment involves worming pups at 10 and 21 days with pyrantel pamoate. The vixen also
should be wormed when the pups are 21 days old. |
| Foxes are commonly infected with ascarids (
Toxocara
canis
), which may cause vomiting, diarrhea, abdominal distention, lethargy, and occasionally intestinal obstruction. Migration of ascarid larvae may cause parasitic pneumonia. Fox pups may be infected in utero or after whelping by ingesting eggs. Treatment involves worming pups at 10 and 21 days of age with pyrantel pamoate or piperazine. |
| Two lungworms,
Capillaria
aerophila
and
Crenosoma
vulpis
, infect foxes. Lungworm infection and the consequent chronic bronchitis or pneumonia may cause death in ranch-raised foxes. (See also
Lungworm Infection: Introduction.) |
| Foxes may be infected with coccidia, the most common being
Isospora
bigemina
. The signs are mild to bloody diarrhea, anorexia, and death. Treatment is the same as for dogs. (See also
Coccidiosis: Introduction.) |
| |
|
Dermatomycosis: |
| Although dermatomycosis appears to be rare in the USA,
Trichophyton
mentagrophytes
has been incriminated in an outbreak. It is reported to be common in foxes in the former USSR. (See also
Dermatophytosis: Introduction.) |
| |
|
Nutritional Diseases: |
|
Rickets may occur in young foxes shortly after weaning. Affected pups appear bowlegged due to curvature of the long bones and joint enlargement. Sometimes the facial bones are distorted and the costochondral junctions enlarged. Rickets is treated by correcting the ratio of calcium to phosphorus in the diet and supplementing with vitamin D. (See also
Dystrophies Associated with Calcium, Phosphorus, and Vitamin D: Introduction.) |
|
Chastek paralysis (
Nutritional Diseases) is a vitamin B1 deficiency induced by feeding certain types of raw fish that contain the enzyme thiaminase. Early in the course of the disease, a few foxes may have an abnormal gait as though their legs were stiff; within 12-36 hr, they have extensive spastic paralysis and are unable to rise. Convulsions often occur shortly before death. Raw fish should be removed from the diet, and daily
injections of 100 U of thiamine given. Cooking of fish that contain thiaminase before mixing prevents the deficiency. |
|
Biotin deficiency occurs when high levels of uncooked eggs (particularly turkey eggs) are fed, causing gray underfur and loss of guard hairs. Preventive measures are described for the disease in mink (
Nutritional Diseases). |
|
Cardiac myopathy has been seen only when fox pups are fed certain commercial pellets. Some factor(s) is deficient in the pup’s early growth phase, which results in an enlarged right ventricle. Supplementing the ration with liver or meat is preventive. |
| |
