Progress In Managing Parasites

Wednesday, June 18, 2025

Emma Borkowski Is Investigating How To Keep Sheep & Goats Healthier

By Emily Mckinlay

The weather this grazing season is just one factor that could increase parasite concerns for sheep and goat farmers, says Dr. Emma Borkowski, an assistant professor at the Ontario Veterinary College, University of Guelph.

Borkowski’s research focuses on parasite control and immune responses in animals affected by parasites. She has been interested in this subject since her undergraduate degree.

“I’ve had a bit of a circuitous route to studying parasites. I took an undergrad course on parasites, and I was fascinated by how they interface with the host and the resulting arms race,” says Borkowski.

“The parasite is a freeloader, and the host is trying to reject it, but the parasite wants to stay. It does not want to kill the host because that would not benefit its survival.

“I always wanted to go to vet school, and while there, I realized how big of a problem parasites are for sheep and goat farmers. I thought that I could clinically make a real difference by studying them.”

For small ruminant farmers, parasites can be costly. It can increase feed and treatment costs, while encumbering performance.

“Even in animals that aren’t obviously sick, you still see a decrease in growth, milk production, and wool production, and those can have pretty impressive impacts,” explains Borkowski.

Weather, management, and individual animal factors can impact the exposure and response to parasites.

“There are a lot of things that affect parasite load. Weather is a major player in the parasite loads we see. Warm and wet weather allows parasites to survive on pasture for longer times.

“There would be an increased burden if there are a lot of animals and not much space, or a lot of manure in a smaller area. There are also factors in animals themselves that can impact parasite load. Younger animals are more susceptible to parasites, whereas older animals have time to develop an immune response.”

Borkowski says that some animals are genetically better at mounting an immune response to parasites. This is the basis for a lot of her work.

“I love working with these industries.

“Sheep and goat farms are progressive and engaged and are so committed to making their animals healthier.”

How can sheep and goat farmers keep their flocks and herds safer from parasites this year, and what new research is in progress?

Monitoring parasites

There are several options for monitoring parasite load, each with its own challenges and benefits.

“There is not a single perfect strategy,” says Borkowski.

The first strategy which provides a quantitative value for parasite load is to perform a fecal egg count. Borkowski says to do this, farmers can set up their own kit.

“This strategy can get expensive when we look at how often we need to collect samples. To address this, I’ve worked with Ontario Sheep Farmers to put on workshops teaching farmers how to check poop samples for parasite eggs.

“Even if you have your own microscope and slides for counting, it is still important to get your vet involved regularly to make sure you are still counting what you think you’re counting. Parasite load can develop quickly.

In the summer, in two to three weeks, animals can go from having a low burden to a lethal burden. When parasites are most active, counts need to occur as often as every two to three weeks.”

This method can be time-consuming, considering both the frequency and the approximate 10 minutes required per sample analysis.

Some producers instead opt to use visual signs to assess their animals. The FAMACHA scoring system is commonly used to assess parasite load.

“This system uses a card with shades of pink to compare with the colour of the mucus membranes in the animal’s eye,” explains Borkowski.

“This only works for blood-sucking parasites, and it means producers need to get their hands on their animals.”

Some farmers will also monitor body condition score and compare animal growth to weight benchmarks. Insufficient performance in these measurements can indicate health challenges but may not be specific to parasite burden.

Managing parasite load can also present challenges.

Management and challenges

For many years, oral drenches of deworming products have been the first-line defence against parasites. This has become less effective as parasites quickly develop resistance to these products.

Borkowski encourages producers to consider other management strategies as the primary approach to parasite management. If those strategies are not successful, this helps keep drenches working as a last resort.

As one approach to managing parasite burden, farmers should be conscious of which animals go on their pasture first.

“Generally younger animals are more susceptible to parasites. Put your young stock on cleaner pastures ahead of adults,” recommends Borkowski.

“If adults contaminate the pasture, pound-for-pound, young animals will pick up more parasites. Adults can handle a bit more contamination. Keep in mind your management groups and use grazing timing strategically.”

Rotational grazing can also reduce parasite load by moving animals away from the pasture before eggs begin to hatch. Since parasites can live on pasture for months, this may require a large amount of grazing land.

Borkowski also recommends that producers can alternate between the livestock species grazed on the land.

“Most of the parasites I study are species-specific and will affect sheep and goats but not cows.

“It helps a lot to graze sheep or goats and then put cows on the pasture. It still exposes the cattle to sheep and goat parasites, but they can’t infect them. The parasites will die off in the cow, and then the cows put their own parasites on the land, which can’t affect sheep and goats.”

As drenches become a less potent option for parasite control, there has also been more interest in selecting for a genetic ability to respond to parasite burden. Borkowski’s lab at U of G has been exploring this opportunity further in sheep and goats, as well as working to interpret current small ruminant parasite research in a Canadian production setting.

In the lab

The challenges of managing parasites and the high potential losses associated with parasites have encouraged Borkowski to find new ways to help sheep and goat farmers.

Her current research focuses are investigating immune responses to parasites and exploring if it’s possible to breed for immunity to parasite burden.

“My lab has kind of exploded in the past year. Right now, I have four graduate and three undergrad students. It’s a lot to look after.”

Currently, Borkowski’s lab is finishing up one project looking at how antibody levels in the gut affect the response to parasites and if immunity to parasites can be bred into goats. This concept has been explored in sheep already, and based on her lab’s results, Borkowski believes this will be a promising tool in goats as well.

“Goats have always been seen as defective at mounting an immune response to parasites.

“If we have a tool to measure their response, and we can determine that maybe that’s not true, maybe we can breed for better goats like we can in sheep.”

The majority of previous small ruminant research in this area has been conducted in different regions globally. Borkowski would also like to investigate these concepts in a Canadian setting.

“To understand the effect of parasites in a Canadian context, we plan to expose animals to parasites in a controlled setting to mimic the Canadian production cycle. We’ll start with constant low-level exposure for a few months to represent summer, then stop exposing them for a few months to simulate winter, and then we will re-expose them like they are going back outside for spring again.

“We want to see how the age and sex of animals affect immune responses. Much of our previous work has been in females and if you are trying to sell breeding stock – especially rams and bucks – we need to understand how we adapt our genetic selection programs to correctly identify the best animals.”

Looking to the future, Borkowski wants to study these immune responses at a cellular level to gain a deeper understanding of what’s behind the responses to parasites.

“For a new line of work, I am trying to understand the cellular signalling that is involved in making these antibody responses to parasites.

“It’s different than the classic response one might think of for vaccines. No one has completely untangled which specific immune cells are involved in this response. They have found candidate cells in humans and mice, but no one has looked at goats and sheep.”

Borkowski hopes this could improve future vaccine development to support sheep and goat producers.

“If we can target vaccines to the specific cell type that makes that specific mucosal antibody, there’s a chance we can use that response to make better parasite vaccines. It is hard to make a vaccine that will cause a strong response in the gut.

“Infectious diseases in livestock often start in the gut or lungs. If we can target directly where the pathogens come in, we can generally make for healthier animals. We are starting with parasites, but who knows where we could go in the future. I like to think about how we can design research that has an impact for farmers on the front line.” BF