Learn More About Deworming Horses and How To Keep Your Horse Healthy

The importance of equine parasite control

Having an equine companion is truly a labor of love. One of the many risks to your horse’s health is parasites. The parasites that infect horses can cause many different health issues. As grazers, all horses are exposed to infection with intestinal parasites on a repeated basis throughout their lives. Low level infestations don’t cause any clinical signs for healthy adult horses, but heavier parasite loads can produce symptoms like these:

• Loss of appetite
• Weight Loss
• Potbelly
• Lethargy
• Coughing
• Respiratory issues
• Poor performance
• Diarrhea or constipation
• Colic
• Tail Rubbing
• Dull, rough coat
• Decreased stamina or lethargy

Although these are the common symptoms seen when a horse has worms, not every horse will exhibit the symptoms listed above. Additionally, other unrelated ailments can also bring on these same symptoms. Given this, it is best not to wait until your horse is sick to address intestinal parasite control. Deworming is an essential, ongoing part of providing your horse the preventive health care he needs. Of course it’s important to contact an equine veterinarian whenever your horse isn’t doing well, but your healthy horse needs a robust GI parasite control plan in place throughout his life.

A successful parasite control plan for horses has three components:

1. Environmental management
2. Fecal analysis to monitor parasite loads
3. Strategic deworming

Environmental Management

Limiting the amount of exposure horses have to their own feces has a huge impact on parasite loads, almost equal to deworming itself. To achieve this:

• Remove feces from pastures and stalls
• Only use properly composted manure when fertilizing pastures
• Rotate pastures
• Provide supplemental hay and forage in feeders off the ground to prevent contamination
• Avoid high stocking rates (1-2 horses per acre is ideal)
• Keep the herd population stable (new horses = new parasites)
• Change bedding frequently
• Clean walls and utensils in stalls

Since younger horses are more heavily impacted by parasites, prioritize cleaner pastures for their use and be especially conscientious about their stalls. Take extra effort to keep nursing mares clean to minimize exposure to foals.

Parasite Load Monitoring

The different types of fecal diagnostic tests that are used to guide deworming strategy can be divided into these two categories:

• Qualitative: examines what kinds of intestinal parasites are shedding eggs in a horse’s stool
• Quantitative: count how many eggs are shed in a given amount of feces via a fecal egg count (FEC). This helps show how heavy a horse’s worm burden is.

Conducting an FEC test before deworming and then repeating it 10-14 days later is called a fecal egg count reduction test (FECRT). It’s a standard method of testing to see if your deworming plan is effective and is reducing the number of parasites present. An FEC test can be helpful for determining which horses are moderate or high egg shedders, and running an FECRT after treatment will show if the shedding of eggs has been reduced.

Strategic deworming

Deworming strategies vary from region to region, so consult local resources to determine the best plan for you. Speak to an equine veterinarian or local extension service for guidance on the best products to use and when to use them. When choosing a dewormer, look at the scientific (generic) name for the active ingredient to know exactly what you’re getting, not the brand name. Take note of the spectrum of action on the label to ensure the dewormer will target the parasites identified by your fecal testing.

Pregnant mares and foals are a special consideration. Even though most of the common dewormers are safe for use in pregnant mares, always check the label to be sure. Many horse farms will deworm the mare shortly after delivery to reduce the risk of exposure to the foal. Foals are usually dewormed every 30-60 days from two months to one year of age, and then they are dewormed on the same schedule as adult horses, with results based on FEC results.

Professional guidance when making decisions about dewormers is essential because a blanket approach to deworming may be ineffective and can even cause complications. Nonselective use of dewormers accelerates the development of resistant parasites, so it’s essential to perform fecal diagnostics before starting treatment to help map out your deworming plan. Rotating dewormers too frequently can also contribute to resistance, so it’s important to avoid that outdated strategy as well. Resistant parasites are difficult to eliminate because the same dewormers administered to the same horses are no longer effective against them. Responsible deworming and vet-informed rotation is fundamental to sustainable equine husbandry. A good nutrition plan, a smart deworming management plan, and clean stables and pastures will go a long way towards helping your horse live a long, happy life.

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