By Mark Andrews 

The American Association of Equine Practitioners (AAEP) has recently issued revised Internal Parasite Control Guidelines to help minimise the risk of parasitic disease and maintain the effectiveness of current drugs for as long as possible by delaying further development of anthelmintic resistance. 

The guidelines, originally created in 2013 and last revised in 2019, account for recent advances in knowledge concerning increased anthelmintic resistance and optimisation of parasite control management practices. They also address common misconceptions and offer parasite control program recommendations for senior horses (over 15 years old), mature horses (between 5 and 15 years old), and young horses (under 5 years old). 

The guidelines were reviewed and updated by the AAEP Internal Parasite Control Guidelines Task Force, chaired by Dr. Nielsen and comprised of ten AAEP members predominantly board-certified in veterinary internal medicine, veterinary parasitology, and/or veterinary microbiology. 

Related: Tackling Dewormer Resistance in Equine Parasites

Related: Spring Horse Health Checkup

The primary target parasites for foals, weanlings, yearlings, and youngsters are, in order of appearance, ascarids, strongyles, and tapeworms. Photo: iStock/Judit Dombovaro 

“We have seen dramatic development in the field of equine parasite control over the past ten years since we first launched these guidelines, and we work hard to keep our recommendations up to date,” said Martin Nielsen, DVM, PhD, DVSc, DAVCM, DEVPC, Schlaikjer Professor of Equine Infectious Diseases at the University of Kentucky. 

Important conclusions to be drawn from the revised guidelines are to: 

Perform fecal egg count reduction tests annually to ensure that you are using effective dewormers in every herd or barn. 

Recognize that no anthelmintic will eliminate all parasitic stages from a horse. 

Continue using fecal egg counts once or twice per year to stratify horses into low, medium, and high shedders to reduce pasture contamination. 

Deworm all horses at a baseline rate and target selected horses more often based on fecal egg counts. 

Not use fecal egg counts to diagnose disease in horses as there is no correlation between fecal egg counts and disease-causing parasite life stages. 

Discontinue deworming all horses with fixed intervals year-round and stop blindly rotating anthelmintic classes. 

The goals of any parasite control program are to minimize the risk of parasitic disease, and to delay further development of anthelmintic resistance and maintain efficacious drugs for as long as possible. 

View the guidelines here: Internal Parasite Control Guidelines – AAEP. You can access the entire guidelines document by clicking the View Resource button. 

Related: Intestinal Parasites in Horses

Related: How to Collect Manure for a Fecal Egg Count

Published with the kind permission of Mark Andrews, Equine Science Update. 

Main Photo: iStock/Sitikka