Monitoring Manure

Dr. Caity Cosentino

Nobody particularly wants to think about what may be in their horse’s manure, but it is important for your horses’s health to monitor the parasite load present throughout the year. Fecal egg counts help to identify high shedders in a herd and also decreases the amount of times horses who are low shedders need to be dewormed. A fecal egg count is a quantitative test that measures the number of strongyle eggs the horse is passing in their manure. Due to the fact that horses are grazing animals, they are constantly exposed to and are picking up parasites, which is why we like to test their manure several times a year. Keeping the worm burden low helps to decrease your horse’s risk of colic, diarrhea, and weight loss due to parasites. Managing the entire herd also helps to keep the pasture contamination low. Most adult horses have a natural resistance to strongyles and using the classic rotational deworming method, have likely been dewormed more often than necessary. The 20% of horses who are high shedders may also be lost in the shuffle and have not been dewormed enough or with the appropriate products. This can contribute to some of the resistance seen to certain dewormers. Horses who are low shedders carry <200 eggs per gram (epg), moderate shedders carry 200-500 epg, and horses are considered to be high shedders at >500 epg. Horses who have a fecal egg count of 0 are not necessarily worm free, but do not have any worms laying eggs at the time of testing.

The best time to check a fecal egg count is before you plan on deworming your horse. You should always check a fecal at the very least, in the spring before deworming and again in the late summer/fall. If your horse is a moderate or high shedder, your veterinarian will likely instruct you to bring another fecal sample back 10-14 days after you deworm your horse to do another fecal test and check the amount of egg reduction to make sure the dewormer worked well. Doing fecal egg counts allows you and your veterinarian to come up with individualized deworming protocols for each horse. Your veterinarian only needs a few fresh fecal balls in a sealed ziploc bag. Keep the sample refrigerated until you drop it off at the clinic/lab and make sure the bag is labeled with your name, your horses name, and the date of collection.

Regardless of your horses worm burden, it is always recommended to deworm them after the first hard frost with a product that kills tapeworms, as these worms do not show up in a routine fecal exam. Make sure to deworm each horse with the appropriate amount of paste according to their weight and administer the product when the horses mouth is free of feed so they do not spit out the product. When possible, it’s best to remove manure from the fields every couple of weeks, but when this is not possible, harrowing the manure in the fields during the summer months can also help to reduce the parasite load on your pastures. Manure is not the most pleasant part of horse ownership, but fecal tests are a critical component to your horse’s routine care.


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