Unseen damage from parasites can steal from your bottom line

Keep some simple tips in mind so performance levels stay strong

Despite great progress in controlling parasites, too many operations fail to consider active ingredients for specific parasite challenges — or even deworming at all. Failure to deworm calves in the spring can limit the calf's ability to reach its full potential.

Advancements have made parasite infestations primarily a subclinical issue, so producers assume there is no problem because they don’t see obvious clinical symptoms or death losses, said Dr. Mark Alley, DVM, managing veterinarian, Zoetis. Because the infestations are subclinical, it’s hard to visualize the calves may be 10 pounds lighter, but, as Dr. Alley said, “In the sale check, that makes a difference.”

“Not deworming nursing calves is probably the biggest obstacle that we have to overcome,” he said. “Most just don’t think it’s an issue.

“Part of the reason for these management decisions comes down to the success of macrocyclic lactones in stopping the loss of cattle due to brown stomach worm (Ostertagia) infestations,” Dr. Alley said. For a time, the industrywide urgency of that problem took the focus away from working to control internal parasites like Cooperia, Nematodirus and Haemonchus.

However, the inappropriate use of macrocyclic lactones is now causing some parasite resistance issues, so producers need to pay attention to ingredient families when selecting parasite control products.1 The three most common ingredient families are benzimidazoles, macrocyclic lactones and imidazothiazoles.

The first step is understanding the limits of current management practices. It is important for cattle producers to work with a veterinarian to do diagnostics and determine what is working in their parasite control program.

As Dr. Alley explains, there are some challenges at the cow/calf level understanding which parasite is present. It is believed older cows develop some resistance to Cooperia. Cooperia, Nematodirus and Haemonchus typically are a greater parasite challenge in younger animals. “But the only real way to determine which parasites are present is to get cultures or PCR [polymerase chain reaction] of the eggs from fecal samples,” Dr. Alley said.

An example Dr. Alley shares is the assumption that winter weather kills a lot of parasites, specifically the larvae and eggs in the environment. “In reality, cold weather doesn’t have a very big impact at all on them,” Dr. Alley said.

As soon as warm weather returns enough to grow grass, the parasite resumes its life cycle on the pastures.

“As a result, we get really short grass that’s just greening up, and with the right-size, right-age calf, they’re going to start nibbling on grass,” Dr. Alley said. “And when they do graze, they may be consuming some parasites with their first forage consumption.”

Dr. Alley recommends cow/calf producers work closely with their veterinarian to develop an effective parasite management program for cows and calves that addresses the parasite challenges in their geographic area.

For more information, visit GetLessParasites.com for solutions from Zoetis. 

About Zoetis

As the world's leading animal health company, Zoetis is driven by a singular purpose: to nurture our world and humankind by advancing care for animals. After 70 years innovating ways to predict, prevent, detect and treat animal illness, Zoetis continues to stand by those raising and caring for animals worldwide, from livestock farmers to veterinarians and pet owners. The company's leading portfolio and pipeline of medicines, vaccines, diagnostics and technologies make a difference in over 100 countries. A Fortune 500 company, Zoetis generated revenue of $7.8 billion in 2021 with approximately 12,100 employees. For more, visit zoetis.com.

For more information, contact:
Kathleen McGinty

Lori Maude
Bader Rutter

1Gasbarre LC. Anthelmintic resistance in cattle nematodes in the US. Vet Parasitol. 2014;204(1-2):3-11.



Mon–Fri, 8:30am–8:00pm ET

This site is intended for U.S. Animal Healthcare Professionals. The product information provided in this site is intended only for residents of the United States. The products discussed herein may not have marketing authorization or may have different product labeling in different countries. The animal health information contained herein is provided for educational purposes only and is not intended to replace discussions with an animal healthcare professional. All decisions regarding the care of a veterinary patient must be made with an animal healthcare professional, considering the unique characteristics of the patient.

All trademarks are the property of Zoetis Services LLC or a related company or a licensor unless otherwise noted. ©2022 Zoetis Services LLC. All rights reserved.