Diagnosis, Treatment and Experience of Canine Distemper in Foxes

Canine distemper is an acute, febrile, highly contagious infectious disease caused by the canine distemper virus, which belongs to the genus Morbillivirus in the family Paramyxoviridae. It can infect dogs, a variety of fur-bearing economic animals and ornamental animals, with young animals being susceptible. It is characterized by digestive disorders and respiratory symptoms, and has a high morbidity and mortality rate. The author's diagnosis and treatment experience is presented below.

1. Diagnosis

Because the clinical symptoms of canine distemper are complex and are often accompanied by mixed or secondary infections, diagnosis should focus on differentiation from rabies, typhoid, infectious hepatitis and leptospirosis. (1) Differentiation from rabies: canine distemper has no laryngeal and masseter muscle paralysis and no aggressiveness. (2) Differentiation from typhoid: typhoid is caused by Salmonella and responds to treatment with antibiotics and sulfonamides, with splenomegaly on necropsy, whereas canine distemper simultaneously presents respiratory symptoms and skin rashes, has neurological symptoms, and does not respond to antibiotic treatment. (3) Differentiation from infectious hepatitis: infectious hepatitis shows transient corneal opacity, prolonged clotting time after bleeding, and characteristic liver lesions and bloody exudate in the body cavity on necropsy, whereas canine distemper has no such changes. (4) Differentiation from leptospirosis: leptospirosis has no respiratory or conjunctival inflammation and shows obvious jaundice.

2. Prevention and Treatment

Only healthy foxes can be immunized. For young foxes, the first vaccination is at 1 month of age, the second at 50 days of age, and a booster at 70 days of age. Adult foxes are immunized twice a year with an interval of 1 month, and immunization is best completed before spring. At present, there is no specific treatment method at home or abroad. Based on many years of clinical practice, the author believes that the following methods can be adopted for fox populations in which an outbreak has occurred but typical neurological symptoms have not yet appeared. (1) Intramuscular injection of immunoglobulin (Ig), 5 mL per dose for adult foxes; (2) intramuscular injection of hyperimmune serum, 3 consecutive times, 5 mL per dose. At the same time, sulfonamides and antibiotics are used to control bacterial complications; for individual severe cases, intravenous infusion of drugs may be given to delay the course of the disease and promote recovery. When serous purulent conjunctivitis occurs, chloramphenicol eye drops are applied to the eyes; when enteritis occurs, oxytetracycline can be added to the feed, 1 tablet per dose for adult foxes, twice a day, or micronomicin can be injected intramuscularly at 1 mL per dose, twice a day; when pneumonia is complicated, penicillin can be injected intramuscularly at 500,000 units per dose for adult foxes, 2 consecutive times, or lincomycin can be injected intramuscularly, once in the morning and once in the evening for adult foxes, 2 mL per dose. Fox populations that have already developed canine distemper should be isolated, cages and equipment should be properly disinfected, feeding management should be strengthened, feeding utensils should be fixed, regularly boiled for disinfection, and the whole population should be vaccinated as soon as possible.