As we move into the warmer months here in Virginia, pasture exposure increases — and so does parasite transmission. Spring is the perfect time to review your horse’s parasite control plan before grazing season is fully underway.

Internal parasites are often a sneaky member of your horse’s environment that can cause potentially serious side effects to their gastrointestinal health if left unchecked and poorly managed. While we cannot see them easily out in the environment, internal parasites can wreak havoc on the horse’s gastrointestinal tract causing irritation to the internal lining of the GI which affects the horse’s ability to absorb adequate nutrients, and in more severe cases, causing colic. Our most common culprits in horses are strongyles, ascarids (“roundworms), and depending on the season, tapeworms.

How do we detect the parasite load in our horses?

The most usefull tool we have is a fecal egg count (FEC).  A fecal egg count measures how many parasite eggs your horse is shedding in their manure. While the FEC levels do not directly correlate with levels of clinical disease in the horse nor do they tell us the exact number of worms inside your horse, they do give us a good indication of

• whether your current deworming program is working
• the effectiveness of the environmental management practices your are using for controlling the populations of parasites

Some parasites, such as tapeworms, may require more specialized testing.

In horses identified as “high shedders”, or horses that have an elevated count of parasite eggs detected on FEC, a fecal egg count reduction test (FECRT) may need to be performed.  This involved performing a fecal test before deworming and again approcimately two weeks after treatment to measure how effective the dewormer is in lowering the parasite levels in your horse.   

Environmental Management Matters

Good parasite control does not rely on dewormers alone.  Pasture management plays a major role in reducing exposure.  As recommended by the AAEP "Wage War on Equine Parasite" guidelines: 

• Pick up and dispose of manure droppings in the pasture at least twice weekly.
• Mow and harrow pastures regularly to break up manure piles and expose parasite eggs and larvae to the elements.
• Rotate pastures by allowing other livestock, such as sheep or cattle, to graze them, thereby interrupting the life cycles of parasites as able.
• Group horses by age to reduce exposure to certain parasites and maximize the deworming program geared to that group.
• Keep the number of horses per acre to a minimum to prevent overgrazing and reduce the fecal contamination per acre.
• Use a feeder for hay and grain rather than feeding on the ground.
• Remove bot eggs quickly and regularly from the horse’s haircoat to prevent ingestion.
  
  

Deworming Protocols

While there are many deworming products on the market for horses, it is important to have a targeted approach when selecting the type and timing of a dewormer. Traditionally, deworming was performed on a regular basis regardless of the level of parasite eggs detected in a horse’s fecal test. Ongoing research in equine parasitology has shown us that many common worms are forming resistance to our commonly used products therefore requiring we use a targeted approach on high shedding individuals for repeated dewormer use.  This is is similar to the way that bacteria can become resistant to antibiotics.  Once resistance develops, we cannot reverse it.  

Please use veterinary guidance for selecting the correct product for your horse based on time of year, environment, and your horse’s age group. Foals, weanlings, yearlings, adults and senior horses are all approached slightly differently in their product and FEC test interpretation so please use veterinary guidance when transitioning between age classes to adjust deworming protocol effectively.

What Parasite Control Looks Like at Woodside

When you work with our team, you can expect:

• Seasonal fecal egg count recommendations

• Identification of low and high shedders

• Targeted deworming guidance

• Recheck fecals when indicated

• Age-specific protocols for foals and young horses
  
  

One of the most common questions we receive is "What does 0 EPG mean?" Occasionally, a fecal egg count comes back as 0 eggs per gram.  This does not mean your horse is completely parasite-free. No horse is ever truly parasite-free. It simply means the parasite burden is low and not actively shedding eggs at the time of testing — which is exactly our goal.  We aim to maintain a low, controlled worm burden that does not impact health.

Strategic parasite control protects your horse today — and preserves the effectiveness of our medications for the future.  If you’re unsure when your horse last had a fecal egg count — or if you’d like to review your farm’s parasite strategy — our team is happy to help.