Coccidiosis in farmed silver foxes (Vulpes vulpes) and blue foxes (Alopex lagopus) in Finland: a case report:

Fur animal farming was initiated during the 1890s on Prince Edward Island in Canada. Farmed silver foxes descend from animals caught from the wild on the island. Finnish fur farming increased during the post war period and in mid-1980s, there were about 6000 fur animal farms, mostly located in Southern Ostrobothnia (Fig.), producing about 8 million fur animals yearly. Currently, there are approximately 1300 fur farms and the yearly production in 2007 was about 2 million fox and 2 million mink furs. The global production at the same time was about 7 million fox and 58 million mink furs. An outbreak of clinical enteric coccidiosis was encountered at a fox farm with silver foxes (Vulpes vulpes) and blue foxes (Alopex lagopus) in intensive farming district of Osthrobothnia in Finland during summer 2008. The breeding animal stock of the farm consists of 1500 silver fox females and 4000 blue fox females. The whelping period of the silver foxes was from April 20 to May 25, and the whelping period of the blue foxes was from ay 5 to June 10. The first clinical signs were seen on silver fox whelps at the age of three weeks. The whelps were unthrifty, their stools were watery, and they littered the floors of the wooden whelping boxes. Their fur was moist and clamped. The females also had moist fur coat, which clamped in the cervical and abdominal areas. There was not increased mortality. The morbidity was about 50 %, with all the whelps in affected culls showing the symptoms. At this time the females are still nursing their whelps, and the whelps keep themselves mostly inside the whelping boxes. After these first symptoms, all whelps were studied clinically. They showed marked unthriftyness and poor growth. The body size of the animals was significantly smaller than the normal at this age. Affected whelps were submitted to post-mortem examination to Finnish Food Safety Authority Evira laboratory in Seinäjoki. In parasitological flotation test from intestinal contents, coccidian oocysts were detected. Faecal samples were submitted for quantitative parasitological analysis and species identification. Of the six silver fox whelp faecal samples, coccidian oocysts were found in 4; max 5600 oocysts per gram (opg), and of the four blue fox whelp faeces, oocysts were found in two, max 120 opg. Two species of Isospora were found. Oocysts of the first one were 30-37x24-28 μm (mean [n=20] 35.3 (SD 0.9) x 26.2 (SD 0.4) μm, and sporocysts measured 15-16x14-15 μm (mean [n=20] 15.5 (SD 0.2) x 14.8 (SD 0.5). Sporozoites measured within sporocysts within oocysts were about 13x5 μm (cannot be measured very accurately). The oocyst surface is colourless, smooth and clear. There is neither Stieda body nor micropyle in the oocyst or sporocyst. No oocyst granule, but sporocyst residuum sometimes present. This species was identified as Isospora canivelocis (Weidman, 1915) Wenyon, 1923. Duszynski et al. [1] consider it possible that this species is identical with Isospora buriatica Yakimoff and Matschoulsky, 1940 in Matschoulsky, 1941 from the Corsac fox and Indian fox, and, more interestingly, with Isospora canis Nemeseri, 1959 from the domestic dog. The other species oocysts measured 21-26x16-21 μm (mean [n=10] 23.4 (SD=1.2) x 18.4 (SD=1.0) μm, and sporocysts measured 11-13x10-13 μm (mean [n=10] 12.2 (SD=1.0) x 11.4 (SD=1.0). The oocyst of this Helsinki University, Faculty of Veterinary Medicine (Docent), Helsinki, Finland Full list of author information is available at the end of the article Juokslahti et al. Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S18 http://www.actavetscand.com/content/52/S1/S18