No Worms, No Worries

Gastrointestinal worms are often a hidden threat to the health of livestock.

“Many producers believe their animals don’t have internal parasites because you can’t see them from the outside unless it’s a really bad infection,” explained Dr. David Shirbroun, doctor of veterinary medicine, Boehringer Ingelheim.

These parasites, however, can negatively impact herd productivity, immune function and even reproductive health. 

To combat these challenges, Dr. Shirbroun emphasized the importance of using effective pour-on dewormers and working closely with a local veterinarian to design a tailored herd health protocol that addresses internal and external parasites, regional disease pressures and nutrition in maintaining overall herd wellness.

Choosing a Dewormer 

Administering the right pour-on dewormer helps maintain herd health and properly manages parasite infections and resistance.

“My number one recommendation for anyone who works with livestock is to work with their local veterinarian,” Dr. Shirbroun advised. “The deworming process varies for different regions, as there are geographical differences and challenges.”

He stressed the need for producers to be vigilant about how they are using dewormers. Because there aren’t many new deworming products on the horizon, it’s important to prevent resistance and overuse in cattle.

“Producers need to make sure they’re using the products we have available in the correct manner, at the correct times and on the correct animals,” he said. “And that’s where working with a local veterinarian is important to make sure you’re doing everything correctly.”

When it comes to choosing a pour-on dewormer, producers should take into account a few key considerations.

Branded Versus Generic

Although branded and generic dewormers may appear similar and share active ingredients, their production process and efficacy can vary.

“It’s important to look for products from major brands with quality research behind them,” Dr. Shirbroun explained. “There’s a variety of products and companies that provide dewormers, and then there are generic versions of those products as well.”

One of the main qualifications for a generic pour-on dewormer is that it has to include the same active ingredient and bioequivalence as the branded product. However, the generic products don’t necessarily require all the other same ingredients to be included.

“With a pour-on, this can influence absorption and, in theory, efficacy as well, even though they’ve got the same active ingredient,” Dr. Shirbroun explained.

Another big difference is the companies themselves. Dr. Shirbroun said a company like Boehringer Ingelheim has in-house sales representatives, veterinarians and researchers that are always working on and standing behind the products. On the other hand, generic companies tend to not have the same level of support, research and guarantees that go into their products.

Regional Differences 

Geographical differences, particularly weather, can affect parasite species and worm pressure. Warmer regions, like the southeast, have more worm pressure due to consistent temperatures.

“The majority of worms in cattle actually are in the pasture,” Dr. Shirbroun explained. “They have to undergo some development on pasture before cattle consume them, at which point they affect the animals.”

In areas where low temperatures are limited, parasites will not die off in the pasture, resulting in increased worm pressure in areas like the south and southeast. Northern states, however, experience heavier winters, which won’t kill all of the worm eggs and larvae but will kill a portion of them.

“An issue we potentially run into with having constant worm cycles in the south, is it becomes much faster for those worms to develop resistance to deworming products,” said Dr. Shirbroun. “This is because they’re not dying off by nature. And so, there’s more chance for animals in the south to pick up worms, prompting producers to deworm them more often.”

Applying Pour-On Dewormer

Proper application of pour-on dewormer ensures livestock receive effective treatment. Dr. Shirbroun outlined the steps below.

Step 1: Know the Animal’s Weight

Before applying dewormer, the first step is to get an accurate animal weight for effective treatment as dewormer products are weight dependent.

“It doesn’t matter whether it’s a pour-on, an injectable or an oral dewormer, you need to have an accurate weight of the animals that you’re treating,” he stressed.

According to Dr. Shirbroun, studies have shown that humans are very poor at judging an animal’s weight, especially cattle, and oftentimes will underestimate a weight.

“If the weight is underestimated, the producer may underdose the animal for the product,” he said. “In this instance, the product will not work as well as it should, and that’s where we can get some resistance.”

If a weight is unknown, Dr. Shirbroun advised against using an average herd weight and instead use the highest weight in the whole pen.

“This will ensure that every animal is getting more than enough product.”

Step 2: Proper Application

Pour-on dewormers are applied with an application gun that draws off of a jug of the product. For proper application, the product must be applied starting at the withers of the animal, going clear along the top line of the back to the tail head in one smooth, continuous motion.

“This spreads the product out along the whole length of the animal’s back allowing for proper absorption,” said Dr. Shirbroun.

A common application error for pour-on dewormer is squeezing the full amount on the animal in one spot.

“I’ve witnessed this several times. A lot of the product can actually run off or splash off, making it not as efficacious.”

Step 3: Application Frequency

According to Dr. Shirbroun, deworming frequency varies geographically and should be based on a fecal egg count reduction test.

“A local veterinarian can perform a fecal egg count,” he explained. “They’ll take a manure sample and test to see what kind of worm prevalence you’re dealing with. From the fecal egg counts, your veterinarian can then determine the treatment plan.”

Traditionally, deworming practices occur twice a year when cattle are moved to or from pasture.

Dr. Shirbroun noted, however, that optimal deworming times may not always align with convenience. He emphasized, again, the importance of working with a local veterinarian to develop a tailored deworming protocol.