Coccidiosis in Donkeys: Intestinal Parasite Infection and Foal Diarrhea

Coccidiosis is a disease caused by microscopic intestinal parasites called coccidia. In equids, the best-known species is Eimeria leuckarti, which has been reported in horses and donkeys. Many infected animals never become seriously ill, but foals are more likely to develop diarrhea and poor thrift because their immune systems are still developing.

The parasite spreads when a donkey swallows infective oocysts from manure-contaminated bedding, feed, water, or pasture. After ingestion, the organism multiplies in the intestinal lining. That can irritate or damage the gut enough to cause loose manure, dehydration, and reduced nutrient absorption.

In donkeys, coccidiosis is most concerning in young foals, recently weaned youngsters, and animals under stress from transport, crowding, weather shifts, or other illness. A positive fecal test does not always mean coccidia are the only cause of diarrhea, so your vet may look for other infectious or management-related problems at the same time.

Coccidiosis starts when a donkey ingests sporulated coccidia oocysts from the environment. These infective stages are passed in manure and can build up in wet, dirty, crowded areas. Foaling stalls, small dry lots, shared feeders, and water sources contaminated with feces all increase exposure.

Young age is one of the biggest risk factors. Foals are exposed early in life, and natural infections have been documented in very young equids. Stress also matters. Weaning, transport, poor weather, concurrent illness, and inadequate nutrition can make clinical disease more likely even when exposure levels are similar.

Heavy environmental contamination is often more important than a single sick animal. Because coccidia are generally host-specific, the main source is other infected equids shedding oocysts. Good manure control, dry bedding, and reducing crowding are key parts of prevention and recovery.

Your vet usually starts with a full history and physical exam. They will want to know the foal's age, how long the diarrhea has been present, whether other animals are affected, and whether there have been recent stressors like weaning, transport, or weather changes.

Diagnosis often includes fecal flotation or other fecal parasite testing to look for coccidia oocysts. In equids, Eimeria leuckarti oocysts are distinctive, but the number of oocysts shed does not always match how sick the foal is. That means a positive test supports the diagnosis, but it does not rule out other causes of diarrhea.

If the foal is weak, dehydrated, febrile, or not improving, your vet may also recommend bloodwork, fecal culture or PCR panels, and sometimes ultrasound or additional infectious disease testing. This broader approach matters because neonatal and young-foal diarrhea can have several causes, and treatment plans change depending on severity.

Prevention focuses on reducing manure contamination and lowering stress in young animals. Clean stalls often, remove wet bedding promptly, and keep feed and water containers off the ground when possible. Good drainage matters because damp, dirty areas help infective oocysts build up.

Avoid overcrowding, especially in foaling and weaning groups. Grouping animals by age can help limit exposure of the youngest foals to heavier shedders. If possible, rotate turnout areas and do not let manure accumulate around feeders, gates, and water sources.

Work with your vet on a practical herd-health plan. A foal with diarrhea may need prompt isolation, fecal testing, and supportive care before the problem spreads or worsens. Routine parasite control for donkeys should be based on your vet's guidance and fecal monitoring, because coccidia control depends heavily on sanitation and management, not only medication.