Internal parasites can be a very serious problem for horses. Even though most owners are aware that deworming is a necessary part of an overall good health program for their horses, the veterinarian is sometimes left out of that loop. Because deworming agents are available over-the-counter, many--if not most--horse owners deworm their own horses without their veterinarian's advice or recommendations. Owners think as long as they are deworming every eight weeks, everything should be fine. But, that's not always true.

The veterinarian's role in parasite control should be to advise and recommend an appropriate deworming schedule and drug for each individual farm or stable. Every farm will have its own needs and/or problems, so one deworming schedule does not fit all scenarios!

For example, a large breeding farm with mostly broodmares and young stock will not have the same parasite issues as a boarding stable filled with adult horses. So, a deworming program that works for the boarding stable might not even begin to work against the parasites that are affecting the young stock at the breeding farm.

Also, many overcrowded farms can benefit from a daily deworming agent that might not be necessary on a farm with only a few horses.

One way to get a deworming program off to a great start is to perform fecal egg counts. This can help your veterinarian determine what parasites are affecting your horses and how effective the current deworming program is at reducing the parasite burden. In this way, if a farm is having internal parasite issues, the problem can be strategically targeted, instead of just shooting blindly from the hip.

Horse owners should tap into their veterinarians' knowledge about the different classes of dewormers. It never ceases to amaze me when I inquire about deworming programs at a new client's farm and they deworm by brand name only. Many horse owners think they are rotating their dewormers, but actually they are using the same drug under a different brand name. Furthermore, most horse owners have not been aware of the problem of tapeworms in horses, or how to get rid of them. As a surgeon, I have long suspected they are much more of a problem than once believed, mostly because I would actually see their freeloading bodies adhered to resected intestines and could not imagine there was not a relationship.

Equine veterinarians are also extremely important assets for helping farm owners with better farm management. This can include ways to help control or decrease parasite numbers by using harrowing techniques during certain times of the year, pasture rotation (if possible), manure management, and dispelling myths about intestinal parasites.

Now is an especially important time for horse owners to have their veterinarians help them become better informed about the new de-wormers coming onto the market. How frequently should they be used? Should I rotate, and if so, how? Is larvicidal deworming necessary? These are all questions that a veterinarian can answer for you. Most importantly, veterinarians can help prevent parasites from becoming a health problem on a farm. The old adage is so true for internal parasites in horses--an ounce of prevention is worth a pound of cure.

About the Author

Christina S. Cable, DVM, Dipl. ACVS

Christina S. Cable, DVM, Dipl. ACVS, owns Early Winter Equine in Lansing, New York. The practice focuses on primary care of mares and foals and performance horse problems.

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