Coccidia (Protozoan Parasites)
Coccidia are microscopic, single-celled parasites (protozoa) that infect the intestinal lining of many animals, including horses, livestock, poultry, and rabbits. Unlike worms, coccidia cannot be seen with the naked eye, but they can cause significant damage to the gut – especially in young, stressed, or intensively managed animals.
Coccidial infections are particularly common in environments where animals are kept in close quarters, such as stables, feedlots, kraals, coops, hutches, and rearing pens. Poor hygiene and wet, contaminated conditions greatly increase the risk of infection.
Why Coccidia Matter
Coccidia invade and multiply inside the cells lining the intestine. As they reproduce, they destroy these cells, which interferes with digestion, nutrient absorption, and fluid balance.
This damage can lead to:
Diarrhoea (sometimes severe)
Dehydration
Weight loss
Poor growth
Weakness
Reduced appetite
Poor feed conversion
Increased susceptibility to other diseases
In young animals, heavy infections can become life-threatening if not detected and managed early.
Coccidia in Different Animals
Equines (Horses & Donkeys)
Coccidia are less common in adult horses but can affect foals and young equines, particularly in crowded or unhygienic conditions. Infected animals may develop diarrhoea, dullness, and poor growth.
Because signs are often non-specific, coccidiosis may be mistaken for other digestive disorders.
Livestock (Cattle, Sheep & Goats)
Coccidia are a major cause of diarrhoea in young ruminants. Stressful events such as weaning, transport, overcrowding, and sudden dietary changes can trigger outbreaks.
Infected animals may show watery or bloody diarrhoea, dehydration, weakness, and weight loss. Even mild infections can reduce long-term productivity.
Poultry (Chickens and other birds)
Coccidia are one of the most important intestinal parasites in poultry. They spread rapidly in flocks and can cause major production losses.
Signs may include diarrhoea (sometimes bloody), weight loss, poor feather condition, lethargy, reduced egg production, and increased mortality in young birds.
Rabbits
Coccidia are extremely important parasites in rabbits, particularly in young or newly weaned animals.
Infected rabbits may show:
Soft stools or diarrhoea
Weight loss
Poor growth
Bloated or painful abdomen
Dull coat
Lethargy
Reduced appetite
Liver coccidiosis can cause liver enlargement, jaundice, and, in severe cases, death. Because rabbits are highly sensitive to gut disturbances, early detection is critical.
How Coccidia Spread
Coccidia have a direct life cycle.
Infected animals pass oocysts in their droppings. These oocysts develop in the environment and become infective. Other animals then ingest them from contaminated feed, water, bedding, soil, or surfaces.
Once inside the host, the parasites multiply rapidly, damaging the intestinal lining before being shed again.
Warm, damp, dirty conditions allow coccidia to spread quickly.
Signs of a Coccidial Burden
Coccidial infections often appear suddenly, especially in young animals. Common signs include:
Diarrhoea
Dehydration
Weight loss
Dullness
Reduced appetite
Poor growth
Weakness
Reduced productivity
Some animals may carry low levels without obvious symptoms, acting as sources of infection for others.
Detection
Coccidia are detected using faecal testing, where specialised methods are used to identify their microscopic oocysts.
Detection allows for:
Early intervention
Targeted treatment
Outbreak prevention
Monitoring of environmental contamination
Reduced unnecessary medication
Because coccidia multiply rapidly, early detection is critical – especially in young stock, poultry, and rabbits.
Treatment & Long-Term Control
Coccidia are not controlled with standard dewormers, as they are not worms. They require specific anticoccidial treatments.
Long-term control focuses heavily on management, including:
Good hygiene and regular cleaning
Dry, well-drained living areas
Avoiding overcrowding
Clean feed and water systems
Stress reduction
Strategic monitoring
Without good environmental control, reinfection can happen quickly – even after treatment.