Deworming Program Integral to Herd Health

Work with your veterinarian to choose the right deworming products and avoid resistance.

You’re spending hard-earned money on dewormers. But are they working hard for you? If you’re using the same product over and over, the wrong product for your operation, or the right product at the wrong time, the answer may be no.

Dr. Doug Ensley, DVM, technical marketing manager with Boehringer Ingelheim (BI), said dewormers are the most overlooked aspect of many herd health programs, but also one of the most important

Like “an iceberg”
There used to be a time when we could look at cattle and know that they most likely had parasites. Today, most of the signs of parasites in cattle are subclinical and may point to a number of other afflictions altogether. Calves aren’t growing like you think they should, weaning weights are down or the gains just aren’t what they used to be. Maybe your reproductive efficiency isn’t what you expected and your pregnancy rates are lower than past years.

“You need to think of parasites as an iceberg,” Dr. Ensley said. “Most of the problem is unseen, but performance is affected. If you’ve done a good job preventing disease, but have not taken a look at your deworming protocol, maybe it’s time to talk with your veterinarian.”

In a nutshell? If you can’t put your finger on what’s wrong, it could likely be parasites.

(Your herd’s) doctor knows best
Dr. Ensley said producers who have concerns about their deworming program should consult with their veterinarian, who can help them decide if they’re using the right products, or if it may be time to switch it up.

“The conversation may go something like this: ‘Doc, I’ve been deworming the same way with the same product for many years. Do you think there’s a value in making a change?’ he said.

Your veterinarian may then suggest a fecal egg count reduction test to see how well your dewormer is working.

“It’s important to work with your veterinarian and utilize a fecal egg count reduction test to assess the efficacy of your current deworming program. Then you can make an informed decision on what products to go to after that,” Dr. Ensley said.

Macrocyclic lactones and benzimidazoles are the two general categories of deworming products on the market, each with different modes of action. Dr. Ensley recommends using a benzimidazoles formulation either in rotation with, or given at the same time as a macrocyclic lactone to prevent resistant parasites. It is also suggested that recently purchased cattle with an unknown dewormer history receive a benzimidazole dewormer before being added to the herd.

Another reason there may be more resistance now than in the past, is the type of products used – but it’s no reflection on their quality. Instead, it’s how certain products are used.

“We used to deworm once or twice a year,” Dr. Ensley explained. “But with the advent of some products that doubled as fly control, producers started using them more frequently, and seeing resistance issues. Proper dosage is crucial when using products like these to help reduce resistance.”

Timing is everything
So, when should producers use dewormers, both to maximize efficacy and minimize resistance? While every operation will differ, Dr. Ensley said there are general guidelines to follow.

His No. 1 piece of advice? Deworm when it’s best for the cow, not when it’s most convenient for you. He also suggests deworming cows prior to the breeding season or prior to calving.

“Just think about when she needs to be at the highest nutritional level,” he said. “That’s a good time to deworm her.”

He also recommends deworming all new animals so they do not have a chance to contaminate your herd. “Ideally, you’re isolating them for a few weeks before commingling them with your other animals.

Sit down with your veterinarian and determine what is best for your operation to maximize the return for your dewormer, and doing what’s best for your animals.