Coccidiosis Affecting Calves in North Dakota

Coccidiosis is an intestinal parasite that may contaminate feed and water.

Ranchers in North Dakota have been observing calves showing signs of coccidiosis this fall and winter, says Gerald Stokka, North Dakota State University Extension veterinarian. The intestinal disease affects several animal species. In cattle, it may produce clinical symptoms from 1 month to 1 year of age, but it can infect all age groups.

“Coccidia are very host-specific; that is, only cattle coccidia will cause disease in cattle,” Stokka says of the protozoan parasite that has the ability to multiply rapidly and cause clinical disease. The major damage to calves is the result of the rapid multiplication of the parasite in the intestinal wall and subsequent rupture of the cells of the intestinal lining.

Several stages of multiplication occur before the final stage, when the oocyst (egg) is passed in the feces. Oocysts are extremely resistant to environmental stress and are difficult to remove from the environment completely. Oocysts must undergo a final process called sporulation before they are infective again.

Oocysts frequently contaminate feed and water. When the sporulated oocysts are ingested by other animals, they start their life cycle over in the new host.

Symptoms
In weaned calves, clinical signs of coccidiosis may develop following stressful events, such as weather changes, or if the calves are in conditions such as being fed and eating off the ground. The conditions this fall and winter, with the ground not frozen under the snow, may have increased the risk of coccidiosis infections.

“Symptoms or signs of coccidiosis will depend on the stage of the disease at the time of observation,” says Stokka.

In general, coccidiosis affects the intestinal tract and creates symptoms associated with it. In mild cases, calves have only a watery diarrhea. However, in most cases, blood is present in the feces. Straining, along with rapid dehydration, weight loss and anorexia may be evident.

Animals that survive for 10-14 days may recover; however, permanent intestinal damage may occur. The lesions associated with coccidiosis found after death generally are confined to the cecum, colon, ileum and rectum.

Laboratory findings should be correlated with clinical signs for a diagnosis, because other infectious diseases such as salmonella and bovine viral diarrhea virus also may lead to blood in the stool, Stokka notes.

The susceptibility of animals to coccidiosis varies.

“Coccidiosis frequently is referred to as an opportunist, which is a disease that will develop when other stress factors are present or when exposure to the oocysts is overwhelming,” Stokka explains.

“The life cycle of coccidiosis in calves is approximately 21 days,” he adds. “This means that if a weaned calf is showing signs and symptoms of coccidiosis at 3 weeks after weaning, then the calf was exposed to the oocysts at weaning time. The logical conclusion is that weaning pens are contaminated.”

Treatment
Infected animals must be treated for the infection and to correct dehydration. Producers should select the proper drugs in consultation with their veterinarian. Sulfa drugs and a therapeutic dose of amprolium are available to treat coccidiosis. Antibiotics may be necessary if secondary bacterial infections are suspected.

Products also are available for treating the entire group of calves, Stokka says. Treatment and prevention are most effective when started early.

Prevention
Stokka and Karl Hoppe, Extension livestock systems specialist, suggest these steps to prevent coccidiosis:

• Move weaning or receiving pens to a clean area free of contamination.
• Increase the amount of space per calf at weaning.
• Feed an additive that can reduce the presence of coccidia.

“Feeding a coccidiostat (decoquinate or amprolium) or an ionophore (monensin or lasalocid) at weaning will reduce the risk of disease,” Hoppe says. “Be sure to follow label claims, because each product will have slightly different label claims.”

“Feeding an ionophore to the cows for reducing the overall coccidia parasites present in the environment also has the benefit of improving feed efficiency,” he adds.

Editor’s note: This article is provided by NDSU Extension. [PHOTO COURTESY NDSU]