What’s a “solid” deworming protocol?

Preventive Care

May 28

Short answer

Deworming is a topic we see many contradicting protocols shared. Determining if your horse is a high or low shedder through a fecal egg count test is the best starting point. If you have a horse on the property that is a high shedder, they’ll require more frequent deworming, because the egg count in their manure is contaminating the pasture/facility they’re in and effecting the other horses. Doing a fecal egg count reduction test will tell you if there’s resistance to the type of wormer being used and a clearer picture of the parasite lifecycle and egg re-emergence. It’s a general safety measure to deworm low shedder horses twice a year at a minimum while targeting bots and strongyles. Fecal tests should be done to ensure efficacy of the dewormer and parasite levels in the herd.

Real-Life Example

You run a fecal egg count test on your horse, and the results come back 500 eggs per gram, so your veterinarian recommends treating with a dewormer and then repeating the fecal test 3 weeks later. The second test results come back 200 eggs per gram. It might seem like the treatment worked because the number dropped, but this reduction may indicate that the parasites present are resistant to the medication that was used. This type of follow-up testing is called a Fecal Egg Count Reduction Test (FECRT). It allows veterinarians to evaluate how effective a specific dewormer is for the parasites present on that farm. If the egg count does not drop enough after treatment, it suggests the medication may no longer be working well against those parasites. That information can then be used to guide future deworming decisions and product selection.

It Depends

Parasite management varies based on:

• Region and climate - infection and survival rate of parasites can vary with temps and moisture levels
• Barn population density - more horses increase the variability of types of shedders parasite load
• Age (young horses often shed more)
• Weak immune status & dewormer resistance patterns - both can increase risk of infection
• Pasture management practices - Dragging pastures to break up manure to dry out on hot days
• Stomach bots (which cause ulcers through mechanical trauma) and encysted strongyles - important to deworm with appropriately dosed and appropriately selected anthelmintic drugs to kill these. At a minimum twice a year, in an average healthy horse.

Herbal products may be an effective part of some programs, but efficacy varies and should not completely replace evidence-based parasite control without veterinary guidance.