A field study was conducted to evaluate the effect of a single oral treatment with 20 mg/kg
body weight (BW) of
toltrazuril (
Baycox 5%
suspension)--TOL--in comparison to a single oral treatment with 1 mg/kg BW of
diclazuril (Vecoxan
suspension orale, 2.5 mg/ml)--
DIC--and an untreated control group (CTRL) on naturally acquired Eimeria
infections in lambs. On a French sheep farm with a known history of
coccidiosis, 75 housed lambs aged 10-14 days were randomised and allocated to one of three groups. During an observation period of 60 days
after treatment, clinical (faecal consistency, BW) and parasitological parameters (oocyst excretion) were evaluated. Excretion in the negative control group started 3 days
after treatment and peaked on the 31st day with a prevalence of 80%. Animals were predominantly infected with Eimeria ovinoidalis. Treatment with
toltrazuril, but not with
diclazuril, resulted in significantly reduced numbers of excreting animals. The number of excretion days and the average oocyst excretion decreased significantly in both the TOL and the
DIC groups compared to the CTRL, with the TOL group showing significantly fewer excretion days and excretion intensities than the
DIC group. Changes in the faecal consistency were moderate throughout the study and not significantly different between the groups. Daily
weight gains were higher in the TOL group compared to the
DIC and CTRL groups which did not differ. This study demonstrates the good efficacy of
toltrazuril administered orally to lambs in the prepatent period in subclinical natural Eimeria
infections in housed lambs.