10 DEPARTMENT OF GAME AND FISHERIES No. 9 



The animals were divided into groups according to their age and sex. The 

 groups ranged from pups under one month to foxes of considerable age. These 

 groups were examined at regular intervals throughout the year and any changes 

 in the blood count recorded. 



It is hoped that this work will provide a basis for a more rational diagnosis 

 of many conditions found in fur-bearing animals. 



Since the breeding of fur-bearing animals in captivity has become an 

 established industry, parasitic infection among them is a matter, not only of 

 scientific interest, but of great economic importance. 



Experience has shown that foxes bred in captivity are almost invariably 

 parasitized by the hookworm, Uncinaria stenocephala. A review of the literature 

 demonstrates that research has, in foxes, apparently been confined to one phase 

 of the subject, namely, the expulsion of the worms. Very little consideration 

 has been given to the question of infestation of the young and to the re-infestation 

 of animals treated with anthelmintics. 



Faecal samples submitted to the Experimental Fur Farm for diagnosis from 

 all parts of the Province of Ontario demonstrate that routine treatment of foxes 

 with anthelmintics will not prevent re-infestation unless the environmental con- 

 ditions of the ranch are given careful consideration. 



Infestation can be prevented only by attacking the parasite before it gains 

 entrance to the body of the fox, and in order to accomplish this, a study of the 

 life-cycle and the environmental conditions under which the ova and free- 

 living larvae develop, successfully, is necessary. 



In order to establish efficient methods of control and the possibility of the 

 complete eradication of the worm, such questions as the age of sexual maturity 

 of the worm, the duration of the larvae stage, and the resistance of the larvae 

 to heat and cold under various conditions, appear to be essential. Investigations 

 of the disease in humans have accomplished much along these lines but nearly 

 all of it has been carried out in tropical and semi-tropical countries under very 

 different climatic conditions from those experienced in Canada, especially during 

 the winter months. 



A survey of the literature available to the writer dealing with Uncinaria 

 stenocephala has revealed only one complete drawing of the male and female 

 (Raillet, 1884). These drawings are too small and make no attempt to show 

 differential characteristics. There also appear to be no microphotographs of 

 Uncinaria larvae. For these reasons, an attempt has been made to present 

 drawings and microphotographs of the various stages of the life-cycle of the 

 worm. 



Other phases of the hookworm problem relating to foxes, including diagnostic 

 technique, egg counting methods, pathology and treatment, have been investi- 

 gated and the findings recorded. 



REPORT OF THE BIOLOGICAL AND FISH 

 CULTURE BRANCH 



Fisheries is one of the most important natural resources of Ontario, and 

 the maintenance of this resource is the chief objective of the Branch. 



