Studies on the efficacy of toltrazuril, diclazuril and sulphadimidine against artificial infections with Isospora suis in piglets.

Abstract

Isospora suis, the causal agent of piglet coccidiosis, is a prevalent and economically important parasite. Three randomized blinded studies were conducted to examine the therapeutic potential of various anticoccidials. Piglets were artificially infected each with 104 sporulated I. suis oocysts at the age of 3 days. Piglets were allocated to groups of 10 to 12 animals as follows: groups A: sham treated control group (each study); studies 1 and 2: group B: toltrazuril, 20 mg/kg body weight (bw), day 2 post infection (dpi); group C: diclazuril, 2 mg/kg bw, dpi 2 and 3; group D: sulphadimidine, 200 mg/kg bw, dpi 5, 6 and 7; study 3: group B: toltrazuril, 20 mg/kg bw, dpi 2; group C1: diclazuril, 15 mg/kg bw, dpi 2; group C2: diclazuril, 15 mg/kg bw, dpi 2 and 9. The following parameters were assessed: studies 1 and 3: general health, feacal consistency, oocyst excretion (opg), body weight; study 2: intestinal pathomorphology and villi length. Severe isosporosis was regularly observed in the sham treated controls (A). Diclazuril (C) and sulphadimidine (D) failed to suppress isosporosis. In contrast, oocyst excretion, diarrhoea and weight gain impairment were efficiently controlled by toltrazuril teatment (B). The villi were on average distinctly longer in the toltrazuril treated animals than in groups A, C and D on dpi 7 and 11. These differences were still visible on dpi 15. The episode of pathomorphological and functional alterations due to piglet isosporosis appeared to be considerably longer than the period of clinical disease.