Wet weather means coccidiosis
March 30, 2009
The wet weather across much of the Tri-State region the past week will predispose young calves to a common parasitic disease, coccidiosis.
It has been estimated that coccidiosis costs the cattle industry more than $100 million dollars annually. The disease is most severe in younger animals. Cows may become somewhat immune to the disease, but they remain carriers without showing any clinical signs. These carrier animals tend to shed more heavily during periods of stress such as cold weather and calving.
Calves are always at risk for coccidiosis. The parasite is ingested by the calf from contaminated bedding and water. Standing water after rains is the primary mean of transmission in our area. Once the parasite is ingested it takes 17 to 21 days for the lifecycle to be completed and clinical signs to begin. This means young calves must be 3-4 weeks old to exhibit signs of coccidiosis.
The egg (oocyst) is consumed by the animal to be infected. The oocyst matures and releases small parasites (sporozoites). These enter the epithelial cells of the small intestine and multiply forming cysts of merozoites. These rupture and some re-infect the small intestine while others move into the large intestine.
As the parasite multiplies in the epithelial cells of the large intestine, they form large cysts. The mermonts released reproduce sexually and again enter epithelial cells and grow into oocysts. When these mature approximately 21 days after ingestion they rupture from the cells and are shed in the manure starting the cycle again.
Clinical signs are usually thought to be bloody diarrhea, but blood may not be present. We rarely see any blood in lambs suffering from acute coccidiosis. The animal may become dehydrated and loses weight. Calves which have had a bout of coccidia are more susceptible to respiratory diseases and other problems. As the cysts erupt from the intestinal cell there is damage done to the gut. This affects gains and the future well being of the calf.
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Treatment is only marginally effective on the severely infected animal. Electrolytes may be needed and amprolium may be added. Broad spectrum antibiotics are needed to prevent secondary infections. B-vitamins help in blood formation if the calf is anemic and also stimulate appetite. Sometimes a nervous condition is associated with coccidiosis. Thiamine has been used to treat this syndrome.
Treatment is more successful during the intermediate stages of the life cycle rather than when clinical signs appear. It is best to treat the entire herd if possible when clinical signs occur. Sulfa boluses have been used as treatment for many years. Some of our producers place pans of water with amprolium in their calf shelters. They report the calves drink it readily.
Many herds address the cows as carriers. Rumensin has been cleared to increase feed efficiency in cows. It has also been used as a preventive therapy for coccidiosis in feedlot animals. Incorporating it into your cow ration can increase feed efficiency while decreasing coccidial shedding.
Coccidiosis is a common and expensive problem in beef and sheep herds. Treatment is inconsistent once clinical signs begin. Good animal husbandry measures and sanitation are important in conjunctiono with a prolonged treatment with a coccidiostat to minimize problems. Contact you veterinarian with questions on diagnosis and treatment.
dave barz is a veterinarian at northwest veterinary supply in parkston, sd.