The issue of anthelmintic resistance has become more publicized and important over the past few years. With no new anthelmintic drugs on the market, how does this developing resistance impact your horses? Will "super worms" develop as a result of this resistance?
Many available tests are capable of detecting one or more types of internal parasites. Always consult your veterinarian regarding the best test for your current needs and for the interpretation of results. Examples of available tests include: Fecal Flotation, Fecal Centrifugation, Home Fecal test kits and ELISA (enzyme-linked immunosorbent assay) blood tests for tapeworms.
One of the more useful tools in a parasite control program is the fecal egg count--microscopic examination of fresh manure for parasite eggs. This simple test allows the veterinarian to determine which parasites are present and whether the infection is light, moderate, or heavy. This information is important in developing a deworming program for your horse or farm, and in monitoring the effectiveness of the program.
Fecal egg count
involves collecting two or three fresh manure balls from the horse to be tested by sending the manure sample to a veterinary laboratory. Results are expressed as eggs per gram (epg) of manure. A fecal egg count of less than 200 epg suggests a light parasite load. Horses with high fecal egg counts of 500-1000 epg suggest the interval between de-worming is too long.
It is important to note that a negative fecal examination does not mean the horse is free of internal parasites. Some types of parasites produce eggs only intermittently. Larvae do not produce eggs at all, and may be present in large numbers in a horse with a fecal egg count of zero. Tapeworm eggs may be missed with routine fecal egg count techniques. The results are most useful when several horses on a farm are tested on the same day. This information gives the veterinarian and farm manager a good idea of the level of parasitism on the property.
There are several different de-wormers, or anthelmintics, currently available. Most are broad-spectrum, meaning that they are effective against several different types of parasites. It is generally best to use a broad-spectrum de-wormer as the basis of your de-worming program. If a specific problem is identified, such as tapeworms or encysted small strongyles, a more specific de-wormer can be used.
No de-worming product is 100 percent effective in ridding every horse of all internal parasites. However, it is not necessary for a product to kill every worm in order to improve the horse's health, minimize the risk of serious disease, improve feed efficiency, and reduce pasture contamination with parasite eggs and larvae.
Consult your veterinarian about the controlling of parasites. Remember, de-worming is no longer a simple do-it-yourself procedure. For more information, contact your veterinarian or the American Association of Equine Practitioners, 4075 Iron Works Parkway, Lexington, KY 40511.