Coccidiosis causes severe diarrhoea and welfare harm in young calves and growing cattle. Prevention through hygiene and anticoccidial treatment significantly reduces suffering.
Clinical coccidiosis causes significant welfare harm in affected calves. The profuse, often bloody diarrhoea results from massive intestinal cell destruction as coccidia complete their life cycle. The resulting enteritis is painful — calves show abdominal straining, hunched posture, and signs of severe discomfort. The protein-losing enteropathy and dehydration cause rapid deterioration and can be fatal within days without appropriate treatment.
Neurological coccidiosis — a severe complication causing seizures, blindness, and ataxia — represents a distinct and even more serious welfare emergency. The neurological signs result from the metabolic consequences of severe disease and carry a poor prognosis. Calves with neurological coccidiosis require intensive supportive care alongside anticoccidial treatment, and welfare outcomes are often poor despite treatment.
Prevention is far more effective than treatment. Reducing the infectious oocyst burden through adequate space allowances, frequent bedding changes, and preventing water source contamination limits exposure. Strategic use of diclazuril or toltrazuril at the start of high-risk periods prevents oocyst multiplication before clinical disease develops. Colostrum management supports calf immunity during the high-risk period.