My Senior Horse Podcast: Australian Equine Internal Parasite Guidelines

Researchers spent nearly five years researching equine internal parasites and their management in Australia. That resulted in published guidelines for horse owners and veterinarians to help them better manage their horses.

In this podcast, we talk to Dr. Abdul Jabbar. He is a Professor in Veterinary Parasitology at The University of Melbourne, where he has worked since 2011. Jabbar holds a DVM degree and has a Masters in Veterinary Parasitology. He also earned a PhD from University of Melbourne. Jabbar has published more than 200 papers in international peer-reviewed journals and six book chapters.

(Editor’s note: The content of this podcast is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

Research Project

Jabbar and his colleagues (some of them from other countries), started by looking at internal parasites of Thoroughbred horses.

“At that time, we didn’t have much information for the parasites of Australian horses,” said Jabbar. He said the majority of equine internal parasite recommendations in that country were based on findings from Western Europe and North America.

“What we wanted to understand was what are the important parasites, what breeders are doing to control these parasites, what veterinarians are doing to control these parasites, and how recommendations for clients are being implemented.

Surveys were undertaken, as well as epidemiological studies. These studies assessed the efficacies of commonly used anthelmintics (dewormers).

Findings

Based on the findings of these studies and surveys, the researchers found there was widespread resistance to anthelminitics.

The Australian Equine Parasitology Advisory Panel that headed up this project included industry stakeholders, clinicians, pharmaceutical companies, and colleague Dr. Martin Nielsen. The latter is now a Professor at Aarhus University in Denmark and is a world-renowned equine parasitologist.

“Our aim was to provide a toolkit for veterinarian-based education for owners toward the sustainable control of internal parasites,” said Jabbar.

The target parasites were small strongyles and roundworms. They also provided recommendations for testing for anthelmintic resistance. “It’s important to test the efficacy of different dewormers commonly used at different properties,” he said. That way they can determine if the products are still effective.

Recommendations

The Equine Parasitology Advisory Panel wanted to provide veterinarians with recommendations on how to use different diagnostic for regular monitoring of the worm burden in horses.

“Also, they should not be relying on the use of synthetic chemicals for the control of these parasites,” stressed Jabbar. “They should also look at other options.”

These management practices could include grazing management and ‘cleaning’ pastures by removing manure. “There is a long list of things people can use at different properties,” he added. “All those things would not be applicable to one particular farm. It depends on the veterinarian to understand the local situation and recommend appropriate tools that could be applied.”

‘Alarming’ Anthelmintic Resistance

Jabbar called the situation in Australia ‘alarming’ when it comes to anthelmintic resistance.

It was 60 years ago when the use of synthetic dewormers came onto the scene. Since then, interval deworming became common practice. The survey showed that the majority of horse breeders are still using interval-based deworming.

“This is one of the key risk factors for development of anthelmintic resistance,” noted Jabbar.

While Australian veterinarians are recommending more modern practices for anthelmintic use, “they are not being translated on the ground,” said Jabbar. “There is a disconnect there.”

Another challenge in Australia is that like in the United States, horse owners can get dewormers from farm supply stores or by ordering them online.

People are using drugs “regularly and indiscriminately whether there is a need or not,” said Jabbar.

Testing Worm Burden

The studies and research found that there wasn’t much monitoring of worm burdens in Australian horses, said Jabbar. This can allow owners and veterinarians to know which horses have high, medium, or low worm burdens.

“Then we need to target those animals that require deworming rather than just a blanket deworming,” Jabbar stressed.

He said the key message is to promote evidence-based practices and stop using a blanket deworming.

Key Takeaways for Australian Horse Owners

Jabbar said if he could say only two messages from the findings, it would be the following:

Regularly check the worm burden to see if there is a need to use deworming products.
If you are using dewormers, regularly check to see the efficacy of that product.

How you do the second point is with a fecal egg count pre-treatment and post-treatment. This will tell you the reduction in the egg count. “That can give you an idea if the drugs you are using are still effective,” he said.

In recent Australian studies, more than 80 different drug efficacy trials were conducted in Thoroughbred horses. They found that small strongyles and roundworms had developed resistance against commonly-used dewormers.

“This is quite alarming,” said Jabbar. “Especially in the case of small strongyles, we found that all the drugs we tested, there was resistance there. Although the level of resistance was variable, the most effective drug was moxidectin. And we also found resistance against that!”

Jabbar said based on the findings of this project, the veterinarians and breeders in Australia want to know more about resistance and the options available for them.