August 2011 Articles

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Updates and New Recommendations for Equine Deworming

Updates and New Recommendations for Equine Deworming Deworming is an essential component of successfully managing your horse’s health and should be tailored for each animal’s specific needs. More than 150 different parasites can potentially infect your horse; however, in North America we are mainly concerned about roundworms (called ascarids), large and small strongyles and tapeworms. Threadworms are not typically included in this list because they usually occur temporarily in foals. Other common parasites of horses include pinworms and bots. The products you choose to deworm your horse and the frequency in which you use them should be partly dependent upon many factors: the age and class of horse you have, geographic region, if the horse is pastured or stalled (and if it is on pasture, how many horses share the same space), climate and the individual needs of your horse. Special consideration should be given to horses living in the South. Here in Louisiana, horses are at risk for increased parasite loads in the fall and in early spring when conditions are wet and warm. However, Louisiana horses are less susceptible to parasite transmission during the summer months due to extremely hot conditions. Currently, veterinarians are recommending an updated deworming schedule, which relies on determining the number of parasites present in a fecal sample, commonly referred to as “parasite load.” Once the parasite load of your horse is classified as low, moderate or high, your veterinarian will be able to help you determine the best treatment schedule. It is now thought that traditional methods of bimonthly rotational deworming are no longer effective due to increasing anthelmentic resistance. It also is recommended that other preventative measures are put into place to reduce your horse’s exposure to environmental contamination. Prevention of environmental contamination is essential to reduce the parasitic load. This method includes proper care of paddocks, pastures and fields and is often overlooked. To ensure the maximum effectiveness of any deworming program, the following are recommended: regular removal and disposal of manure at least twice a week, harrowing pastures to break up manure piles and expose the eggs and larvae to the elements, ussing rotational grazing by moving horses between pastures to reduce parasite ingestion, reducing the number of horses per acre, which translates to decreased fecal contamination, and elevating feed off the ground to prevent further parasite ingestion. While no deworming program will be suitable for every horse, the following recommendations should be effective for the average adult horse living in Louisiana with a low to moderate parasite load. Month Product February/March Ivermectin May/June Ivermectin/Proziquantil November/December Moxidectin/Proziquantil If you have any questions regarding specific recommendations for your horse, please contact your local veterinarian. Source: LSU AgCenter, Dr. Neely Heidorn, nheidorn@agcenter.lsu.edu