Researchers Test Herbs for Deworming Effectiveness in Horses
From Kentucky Equine Research:
Largely due to inappropriate use of chemical dewormers, known also as anthelmintics, the equine industry is now faced with widespread parasite resistance. Lulled by the idea of “natural” or “environmentally friendly” treatment options, some owners are now using plant additives to deworm their horses. Little science supports these products as effective dewormers, leaving horses at risk of parasite-related illness. In particular, small strongyles are clinically relevant internal parasites that may cause colic, diarrhea, weight loss, and even severe illness during their larval stage.
One example of a nonchemical dewormer studied to date includes sainfoin, which proved to reduce fecal egg counts.
“Other plant products purported to have anthelmintic or immune-boosting properties to ward off parasitism include echinacea, curcumin, and mugwort,” said Catherine Whitehouse, M.S., a Kentucky Equine Research nutritionist.
Commercial products containing echinacea, curcumin, or mugwort were administered to three groups of healthy Welsh Ponies with fecal egg counts greater than 200 eggs per gram of feces. Doses used were 1.8 times the suggested manufacturer dose, and ponies were treated for 10 to 30 days depending on the specific plant additive. The ponies’ regular diets were maintained during the study, which included wheat straw and pellets containing wheat straw, oats, wheat bran, dehydrated alfalfa, barley, dried beet pulp, and sugarcane molasses. Water was supplied ad libitum.
The feed additives were mixed with the pellets morning and night. Each pony was individually tied to the feeder for 30 minutes to ensure each animal finished its entire ration.
“No significant differences in fecal egg counts or larval development from harvested fecal samples was observed between the control ponies and any of the three treatment groups,” explained Whitehouse.
That said, there was still some deworming success based on the fecal egg count reduction test. Specifically, fecal egg counts were reduced by 25.2%, 32%, and 38.6% by the echinacea, curcumin, and mugwort, respectively.
The researchers concluded, “Our efficacy results do not justify the practical use of these additives. This study may prevent horse owners, breeders, and veterinarians from making mistakes in the management of small strongyle infections in equids. Undoubtedly, further studies should be conducted in the future to standardize the correct dose of plant feed additives against small stronglyes in equids.”
Currently, horse owners are strongly advised to stop rote chemical deworming of their horses and to instead partner with their veterinarians and follow recommendations made by the American Association of Equine Practitioners.
“Offering products that support your horse’s immune system may also bolster their ability to fight internal parasites. Look for Kentucky Equine Research’s marine-derived oil, EO-3, or our water-soluble vitamin E product, Nano-E,” Whitehouse advised.
Pasture management practices such as manure removal, harrowing, and pasture rotation to avoid overgrazing are encouraged to help reduce exposure to parasites and minimize the chances of developing a heavy load.
*Malsa, J., F. Reigner, M. Riou, A. Gesbert, F. Guegnard, N. Perrot, D. Serreau, G. Fleurance, and G. Salle. 2024. Evaluation of plant commercial feed additives for equine cyathostomin control. Journal of Equine Veterinary Science:105197.
