“Don’t let your comfortable cattle become ‘lousy’ cattle,” urges Dr. Larry Hawkins.

Hawkins is referring to the tiny louse, which can inflict major damage on entire herds of cattle during outbreaks in cold weather.

Lice are cold-season insects, but proactive management, including monitoring and treatment, can keep your cattle healthy throughout fall and winter. (Photo by Robert Waggener)
Lice are cold-season insects, but proactive management, including monitoring and treatment, can keep your cattle healthy throughout fall and winter. (Photo by Robert Waggener)

“Don’t wait for such outbreaks to happen,” Hawkins emphasized. “Keep on top of this potentially very serious problem so your beef and dairy cattle stay healthy and comfortable.”

Hawkins, senior technical services veterinarian with Bayer Animal Health, said he has been called to ranches and farms dealing with train wrecks caused by lice.

“As we move into late fall, lice begin to reproduce in exponential fashion, and by December and January you can see huge populations on many animals in a herd,” he said.

“Once lice become reproductively active when temperatures fall, a single insect can lay about 40 eggs in a three-week period of time.”

The number of lice in an untreated animal can quickly soar into the thousands, causing extreme irritation for the cattle and economic loss for the beef or dairy cattle producer. But careful and ongoing monitoring coupled with proactive treatment will help keep lice populations in check—and your cattle performing well throughout late fall and during the winter.

“A good time to treat is when you’re preg-checking animals, and then be aware of things throughout winter,” said Hawkins, who noted that if a few cattle begin to show any signs of irritation, get them in the chute for a close examination.

This will help determine what is causing the extreme annoyance, whether lice, mites or something else.

If more than five lice are discovered in a square inch, treatment should begin immediately to avoid an outbreak.

“Some of the conventional products will very effectively kill adult lice if used properly, but they won’t kill the eggs that are on the animals at the time of treatment,” Hawkins said. “Those eggs will hatch within the next week and then it takes another week for the population to begin building again, so if you don’t treat again the cycle starts all over.”

To avoid another outbreak, Hawkins recommends following the first treatment with a second application in three weeks.

“That should get the lice population to very, very low levels—even near zero,” he said. “This should keep the problem under control through most of the winter, but you still need to keep on top of things.”

Treatment options include self-application devices, such as dust bags and oilers, non-systemic pour-ons and endectocides, or systemic pour-ons.

“The endectocides (avermectins and milbemycins) will help control both lice and mites, including the chorioptes mites, which can be a real problem in dairies,” Hawkins said.

“Another very good option to consider is the new technology that is available. It has a pyrethroid, which kills the adults, and it also has an insect growth regulator, which stops the eggs from hatching,” he added. “This gives you very good control with one treatment instead of the customary two.”

Regardless of what treatment is used, Hawkins said that keeping a close eye on your cattle, conducting regular examinations with a few animals and working closely with your large-animal veterinarian will pay big dividends for both the health of your herd and your pocketbook.

“Don’t let lice affect cow comfort,” he emphasized.