What is a Fecal Egg Count (FEC)?
A fecal egg count is laboratory analysis of an animal’s feces to determine how many internal parasite eggs are being shed into the manure. This allows us to calculate the number of parasite eggs per gram of manure.
The current recommendation is to deworm based on results of a fecal egg count rather than an every other month rotation. FEC’s are useful to help us determine:
- Which dewormers are effective on a particular farm
- Which horses are high vs low shedders by nature (creating a parasite management program for each horse)
- How often deworming is necessary
Why Do Some Horses Shed More Eggs Than Others?
Not all horses kept in the same pasture or on the same farm are affected by worms equally. It is estimated that approximately 20% of horses in a herd will carry 80% of the total parasites on a farm!
All horses are exposed to parasites throughout their life. Some horses develop immunity to parasites and are not as susceptible as other animals. The immune systems of young horses (less than 3 years) and older horses (over 20 years) are more susceptible to parasites and may carry higher loads.
What is a High, Medium, or Low Shedder?
Adult healthy horses consistently carry similar worm burdens through the year, which allows us to customize parasite management plans based on the level of intestinal parasite eggs that they are shedding.
High Shedding horses will need more frequent strategic deworming, compared to Medium or Low shedders.
High Shedders: will have over 500 egs per gram of feces
Medium Shedders: 200-500 eggs per gram of feces
Low Shedders: less than 200 eggs per gram of feces
This allows us to decrease unnecessary use of dewormers by using them strategically in the horses with less natural immunity to intestinal parasites
We recommend a fecal egg count every Spring (April) and again in the Fall (October/November) for some animals. Follow up Fecal Egg Counts may need to be performed at specific times throughout the year depending on your parasite management program.
What else can we do to control Parasites on farm?
- Don’t overstock your pastures (over grazed pastures increase ingestion of parasite eggs)
- Regularly dispose of manure and don’t spread onto pastures currently being grazed
- Drag/harrow paddocks to break up manure piles and leave open for 2-3 weeks
- Use feeders for hay or grain rather than feeding off the ground
- Keep foals and weanlings separate from yearlings to help prevent ascarid infections
Why do we care about changing the way we deworm?
Across the country, all types of horse farms have reported resistance to certain dewormer classes. The most commonly reported resistance is to fenbendazole (sold as Safeguard and Panacur) and ivermectin products. There are no new dewormers being developed for horses. Our goal is to be smarter about the way we are using the dewormers we have to minimize resistance.
Collect and submit a fecal sample on each horse in the spring (March/April). This can be done the day of your annual wellness visit for vaccines/coggins/dental and given to the veterinarian on the farm.
- For each horse to be tested a fecal sample is submitted BEFORE deworming.
- To collect a fecal sample:
1. Collect 2 fecal balls of manure ideally passed within 1-2 hours but definitely less than 24 hours
2. Place the manure in a plastic ziplock bag, removing all air possible
3. Store the sample in a refrigerator until it can be picked up or delivered to us.
You will receive a Parasite Management Plan for each horse.
- Most low shedding horses will have Fecal Egg Counts and be treated biannually (early spring and fall)
- Moderate and high shedding horses will need additional deworming and strategic Fecal Egg Count Assessments during times of highest parasite risk.
- Foals and Senior horses will require different strategic deworming programs than mature horses.
To monitor for resistance. Once per year a Fecal Egg Count Reduction should be performed on at least one horse on your farm.
- Submit a fecal sample just prior to deworming and 10-14 days after deworming depending on dewormer used.
- Comparing the Fecal Egg Count results from just prior to deworming to those two weeks after deworming helps us determine if this dewormer is still effective for parasites on your farm.