Efficacy of prophylactic dosing of diclazuril for the prevention of coccidiosis in captive-reared North Island brown kiwi (Apteryx mantelli) chicks

Kiwi (Apteryx spp.) chicks in conservation captive-rearing programmes commonly suffer from coccidiosis, a parasitic disease that can cause significant morbidity and mortality in young birds. Current management combines preventative husbandry with treatment using coccidiocidal drugs. However, evidence suggests a lack of efficacy of toltrazuril, the primary drug used to treat coccidia, and limited information is available on safe and effective therapeutic alternatives for juvenile kiwi. This study evaluated the prophylactic efficacy of orally administered diclazuril (Coxiril 0.5% (5 g/kg) microGranulate premix, Huvepharma) for preventing coccidiosis in kiwi chicks naturally exposed to infection in captive-rearing facilities. Kiwi chicks (n = 6) received in-feed diclazuril at 0.5 mg/kg daily for 30 days, starting on the day of transfer to outdoor pens. An untreated control group (n = 6) was monitored in parallel. Health was monitored via clinical observation and blood biochemical analyses, while drug efficacy was measured using a combination of faecal oocyst counts, plasma concentration of diclazuril, and a molecular assay to assess changes in Eimeria spp. composition. In-feed diclazuril was well tolerated, with no adverse effects observed. Treated birds shed significantly fewer oocysts than control birds (p = 0.021). Changes in coccidia species composition suggested differential susceptibility of some kiwi Eimeria species to diclazuril. Further investigation of the optimal dose and treatment duration is recommended before integration of diclazuril into standard management protocols.