On the parasites of silver foxes on some farms in the south-west

Abstract

INTKODUCTIONIt had been hoped to follow the survey outlined here by a series of controlled experiments designed to elucidate (i) the more important features in.the life cycles of, in particular, the nematode parasites of the silver foxes, and (ii) the effects of the various infestations on the foxes, and methods of controlling them, or of ameliorating the damage done. In fact, in September 1939, we were on the point of obtaining, by the kind courtesy of several of the fox farmers with whom we had been working, a number of experimental animals. With the advent of war, however, it became apparent that this work must be at least temporarily abandoned. The results of the survey seemed to us to be sufficiently interesting in themselves, and to provide a basis for future observations, should they at any time become possible. We have therefore decided to publish them as they stand.The figures analysed in the following pages have been obtained during the course of an investigation into the diseases of silver foxes and of methods of controlling or preventing their outbreak. Carcasses and samples of faeces have been obtained from fourteen farms altogether. In most cases the material was first obtained as the result of a specific request to the owner, and some selection of the carcasses to be examined was made with a view to obtaining a representative sample from the farm. In addition to these animals, however, other carcasses were sent in with requests for information as to the cause of death. These animals were examined by the same routine methods as the others for which request had been made. In some cases the only animals obtained from a farm have belonged to the second category, the farm having been for various reasons omitted from our initial survey.In all 154 carcasses have been examined, and in most cases the worm populations related to the worm egg counts obtained by the Stoll dilution count method. Of this total twenty-seven animals were selected during the 1937 season, and their faeces examined at about fortnightly .intervals over a period of up to 2 months before they were pelted. As will be seen from the analysis of the figures presented later, the worm egg counts fluctuated violently and in a very irregular manner, and it proved impossible to discover any quantitative relation between the counts from the faeces and the worm populations in the carcasses.' In addition to the silver foxes, we have examined nine adult and four cub red foxes, in order to determine how far it is possible that the silver-fox farms may be infected from wild red foxes living in their neighbourhood. Some of these carcasses have been obtained locally, but as most of the area is hunted it has not been possible to obtain an adequate number to provide a true indication of the extent to which the wild species is parasitized. We have had to rely on chance deaths in traps, etc. The local foxes have therefore been supplemented by animals obtained from near Oswestry, where, in the absence of hounds, the foxes are shot.

Studies of disease in the Red fox (Vulpes vulpes) in Northern Ireland

“…The variety of helminth species recovered in the study is very similar to that recovered in England by Blackmore (1964) and Watkins & Harvey (1942) with the exception that lung worms, Capillaria and Eucoleus spp. were not detected here.…”

“…Blackmore (1964) notes that two cubs between three and four weeks old died while being hand reared and that death was associated with a large ascarid burden. Watkins & Harvey (1942) on a study largely on the Silver fox (a mutant form of the American Red fox Vulpesfulvo, thought to be conspecific with V. vulpes) found these nematodes, which could be a serious disease in cubs, in very young foxes. T. canis was recovered from a cub between seven and 14 days old and U. stenocephala in animals only 46 days after birth.…”

Red foxes (Vulpes vulpes) in Ireland as hosts for parasites of potential zoonotic and veterinary significance

“…Bar= 1 mm. (b) Life cycle of A alata; the trematode uses two intermediate hosts, the first a water snail, the second a frog PAPERS & ARTICLES (Willingham and others 1996) and between 45 and 78 per cent in Britain (Watkins andHarvey 1942, Beresford-Jones 1961).…”

The coccidian parasites (Protozoa, Apicomplexa) of carnivores

“…Watkins and Harvey (1942) found this species (the only coccidium they saw) in 11 out of 52 silver fox cubs dying out of pelting season in England. They also found it in perhaps 10% of the adult and perhaps 25% of the cub foxes from some 15 fox farms in England.…”