14 DEPARTMENT OF GAME AND FISHERIES No. 9 



genie organisms were isolated with the exception of a pure culture of streptococci 

 from two cases. Injections of this organism in foxes and other experimental 

 animals failed to give rise to any disease. It would, therefore, appear to be a 

 secondary invader of a non-virulent type and certainly not responsible for the 

 outbreaks. Smears and cultures of the heart's blood failed to show any organisms, 

 nor did the injection of heart's blood intravenously in the ear veins of rabbits 

 and subcutaneously and intraperitoneally in guinea pigs give rise to any 

 symptoms of disease. Emulsions of ground-up spleen and brain also failed to 

 produce the disease in rabbits and guinea pigs. 



Transmission to Foxes. — The clinical picture presented by sick foxes at the 

 ranch closely resembled that of canine distemper, which is known to be caused 

 by a filtrable virus. As no pathogenic organisms could be isolated, experiments 

 were made in infecting fox pups. Intramuscular injections with 2 c.c. of an 

 emulsion of the spleen and brain hypodermically produced the disease without 

 fail. The material for injections was obtained from a fresh carcass of a fox 

 dead of the disease on the affected ranch. 



A Berkefeld filtrate of the brain and spleen of a fox dead of the disease 

 was obtained, using a 6- by 1-inch "M" candle. This was plated on blood agar 

 to be sure it contained no organisms and was injected intramuscularly and 

 produced the disease in its typical form. 



By the use of fox pups for experimental animals the incubation period 

 was determined as being from two to three weeks with death in three to four 

 weeks. The disease has been proved to be due to a filtrable virus. 



Transmission to Ferrets. — Encephalitis is the only other present known in- 

 fectious disease of foxes caused by a filtrable virus. Green ^ states definitely 

 that fox encephalitis does not afifect ferrets, nor was he successful in transmitting 

 encephalitis to ferrets by injections with the virus of fox encephalitis. It is 

 well established that the virus of canine distemper is virulent to ferrets. 



Healthy three-month-old ferrets not previously exposed to distemper were 

 secured and injected intramuscularly with an emulsion of the ground-up spleen 

 and brain of one of the foxes dying after the above experimental injections. They 

 developed typical canine distemper symptoms and also those of fox distemper, 

 viz. purulent discharge from the eyes and nose, rapid emaciation, rigours, coma, 

 and death. 



A Berkefeld filtrate prepared as outlined above was also injected in a second 

 series of ferrets and likewise produced the disease. 



Summary. — A severe infectious disease of foxes has been studied over a 

 period of two months. Some 200 cases have been observed and the opportunity 

 was afforded of post-morteming numerous carcasses as well as some 20 foxes 

 dead within 12 hours for ideal bacterial examination. The disease has been 

 proved to be caused by a filtrable virus and is not transmissible to rabbits or 

 guinea pigs but is virulent to ferrets. From the symptoms, post-mortem, its 

 highly infectious character, transmission to ferrets and its being caused by a 

 filtrable virus the disease would appear to be analagous to canine distemper. 



Infectious Pneumonia 



Several severe outbreaks of pneumonia have been reported in the Province 

 during the past year. There appears to be two separate types of infection. 

 Lobar pneumonia affects fox pups causing a peracute fatal pneumonia. It is 



ijour. of Hygiene, July, 1930. 



