a group of calves
15 March 2021

Be Proactive Against Coccidiosis


Posted by  | Jerry Mechor, DVM, MVSc | 15-Mar-2021

If you’re in the cattle business, you’re probably familiar with coccidiosis. It’s a crippling disease in cattle that can result in devastating losses, including animal mortality, growth reduction, permanent stunting, feed conversion reduction, treatment expenses and prevention costs. Fortunately, there’s been a lot of research done to help prevent and accurately diagnose coccidiosis in cattle. 

Getting the Diagnosis Right

A pathogenic species from the genus Eimeria causes coccidiosis. In cattle, 13 intestinal Eimeria species have been identified, although not all cause disease in animals. Eimeria bovis and Eimeria zuernii are two species that have been shown to have the greatest potential for disease infection.1 This is important because although lab results may indicate a high number of coccidiosis oocysts present in an animal’s feces, species identification is critical to establish the presence of pathogenic species.

While diarrhea is a common symptom of coccidiosis, diarrhea in calves does not always equate to coccidia. Bacteria, viruses, parasitic infections, dietary changes and nutrient deficiencies are other common causes of diarrhea in weaned calves. A thorough examination and diagnostic testing can help confirm a positive case of coccidiosis.

Accurate diagnosis of coccidiosis requires several steps:

     1. Look for clinical symptoms and conduct a thorough examination of sick calves.

     2. Conduct necropsy examinations on dead animals.

     3. Confirm the presence of pathogenic species of Eimeria oocysts through lab testing.

Lab testing is of vital importance for confirming coccidiosis in cattle. I recommend obtaining five to eight samples of feces from both healthy calves and from those suffering from disease. Submit them for virology, bacteriology and parasitology testing, and be sure to look at cocci speciation on the lab report.

Once lab results are in, a positive diagnosis of coccidiosis can be made by:

  • Confirmation of a significant number of pathogenic coccidian species in feces
  • Assessment of appropriate clinical symptoms, including diarrhea and dysentery
  • Confirmation by pathology, if appropriate
  • Ruling out of other diseases

Based on the diagnosis, producers can institute a treatment and prevention plan, whether it is for cocci, challenges with bacterial overgrowth due to diet changes or other intestinal issues.

Prevention Is Key

Eimeria oocysts can remain viable in the environment for up to a year, withstanding environmental challenges because they have a thick cell wall that helps protect them. They’re resistant to freezing, extreme pH changes and low oxygen availability, meaning they can thrive in extreme conditions. One key to coccidiosis prevention is a clean living environment for animals with plenty of exposure to direct sunlight, which can be detrimental to oocyst survival. Covered areas that are wet and contaminated with feces provide a favorable environment for disease transmission.

Another way to help prevent disease transmission is to reduce animal stress, because stressed cattle may be more prone to coccidiosis infection. Weaning, transporting, extreme weather, changing diets and overcrowding are all stimuli that could put animals at greater risk for developing coccidiosis.

Environmental management to minimize exposure of animals to fecal-contaminated housing, feed, water and soil is critical to prevent coccidiosis. These tips can help keep cattle healthy:

  • Ensure that cows are clean before entering maternity areas
  • Minimize the time newborn calves spend in the maternity pen
  • Clean maternity pens regularly
  • Thoroughly clean calf housing to remove all organic matter; expose to direct sunlight if possible
  • Minimize contact between calves
  • Isolate animals with severe clinical symptoms
  • Avoid feeding on the ground
  • Maintain clean waterers and feeders
  • Avoid overcrowding and reduce stress
  • Rotate pastures
  • Encourage early dry matter intake in young calves
  • Feed adequate levels of Rumensin® for the control and prevention of coccidiosis prior to exposure

For the prevention and control of coccidiosis, Rumensin is the most potent feed ingredient available.2 It kills coccidiosis parasites at three different stages in the life cycle instead of merely slowing their development.3 Rumensin is more efficacious at lower doses compared to other ionophores.2

Taking appropriate steps to prevent coccidiosis and accurately diagnosing positive cases can help dairy producers save time and money. Treating for the disease without confirming it’s the cause of symptoms in cattle could be a costly mistake. For more information about how Rumensin can help prevent coccidiosis in your cattle, contact your Elanco representative.

The label contains complete use information, including cautions and warnings. Always read, understand and follow the label and use directions.

CAUTION: Consumption by unapproved species or feeding undiluted may be toxic or fatal. Do not feed to veal calves.

Calves (excluding veal calves)  

For the prevention and control of coccidiosis due to Eimeria bovis and Eimeria zuernii: Feed 10 to 200 g/ton to provide 0.14 to 1.0 mg/lb of body weight/d, depending upon severity of challenge, up to a maximum of 200 mg/hd/d. The Type C medicated feed must contain 10 to 200 g/ton of monensin (90% DM basis).  


1Bangoura B, Bardsley KD. Ruminant coccidiosis. Vet Clin North Am Food Anim Pract. 2020;36(1):187-203. doi: 10.1016/j.cvfa.2019.12.006.

2Long P, Jeffers T. Studies on the stage of action of ionophorous antibiotics against Eimeria. J Parasitol. 1982;68(3):363-371.

3McDougald L. Chemotherapy of coccidiosis. In: Long PL, editor. The Biology of the Coccidia. Baltimore MD: University Park Press;1980:373-427.

Rumensin, Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates.

© 2021 Elanco.



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    Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates. © 2022 Elanco.