[Safety of a new anticoccidial agent, clazuril, during reproduction in carrier pigeons].

In a six-month study, the safety of repeated treatments with clazuril, a new anticoccidial agent for the treatment of pigeons, was evaluated during 4 to 5 consecutive reproduction cycles. Clazuril was administered weekly at the recommended therapeutic dose level of 2.5 mg/pigeon and at twice this dose. The results were compared to placebo treatment. Evaluation was based on the following parameters: reproductive behaviour, egg laying, fertilisation, embryonic mortality, hatching, percentage of weaning and time interval between consecutive reproductive cycles. Maternal-paternal toxicity (body weight evolution, feather coat) and tolerance in newborn pigeons (general behaviour, daily gain in body weight, feathering, skeletal anomalies) were also evaluated. In all the treatment groups, reproductive performance was comparable and no drug- or dose-related side-effects were observed. Fertilisation, embryonic mortality and the time-interval between the consecutive reproductive cycles remained within the normal physiological range. Hatched pigeons showed a satisfactory daily weight gain and deaths among these birds were exceptional. Tolerance of clazuril in adult as well as in day-old pigeons was exceptionally good and body weight evolution, feathering and mortality were not adversely affected. No drug-related pathological findings or skeletal anomalies were detected in the animals at autopsy. It can be concluded that repeated treatments with clazuril are entirely harmless for pigeons during reproduction, even at double the therapeutic dose level. Clazuril is well tolerated by newborn and growing pigeons, which means that pigeon house group treatments during reproduction may be performed without any risk.