Distemper in the silver fox (Culpes vulpes).

Abstract

In a previous communication 1 there was reported the isolation of organisms belonging to the genus Salmonella from foxes dying of an epidemic disease. These organisms have been shown to be very pathogenic for foxes. When injected into healthy foxes a disease is consistently produced, death usually occurring in from 14 to 20 days. The organism has been isolated from the spleen of an animal killed 5 days after injection, but no gross pathological changes had yet occurred. In artificially infected foxes the pathology at necropsy is characterized by an intestinal inflammation and enlargement of the spleen, lungs usually being normal. The spleen is sometimes enlarged 20 times, by weight. The same picture has been produced by a direct injection of material from carcasses of ranch animals.

Further experimental work has been carried out in vaccination of ranch animals with these organisms, and further studies of disease occurring in these animals, using for transmission experiments foxes which also have been immunized with a Salmonella vaccine. An epidemic on a large ranch had previously been studied in which the picture of a Salmonella infection was the characteristic pathology. The organisms were isolated from many animals. Vaccination of the entire ranch of more than 500 animals appeared to control the epidemic, which was mainly among foxes 4 months old.

During the ensuing months there were a few scattered deaths, and 6 months later there was an increase in the number of deaths sufficient to indicate the presence of a mild epidemic. In the second epidemic quite a different picture was presented from the one previous. There were no external signs of disease. Some animals were found dead; others were found in convulsions, dying shortly afterward, and a few were sick for several days before death.