t is that time of year again — when we traditionally begin treating our horses for worms.
There are many different types of intestinal parasites (worms) that can affect your horse. Giving treatment without knowing which worms, or if there even are worms, can be detrimental to the horse population as a whole and we need to recognize this now so we have deworming medications to use in the future.
It has become common practise that horses must be dewormed every spring and fall. Some will go even further and deworm their horses up to once a month. The evolution of this practise began many years ago with the transition from tube deworming — a veterinary procedure in which a deworming agent was passed directly to the stomach — to the current method of administering a deworming paste into the horse’s mouth. The change in method meant horse owners could now make the decision on when to deworm their horses. This was a great advance, but it slowly eliminated the veterinarian from the deworming discussion.
The loss of information about worms and their life cycles quickly followed; hence the most appropriate schedule for deworming horses was somewhat lost as well.
Each worm or parasite has a specific life cycle and susceptibility to the deworming medications. Most worms have about a three-week life cycle, meaning that adult worms lay eggs today which will hatch and continue the cycle every three weeks. This is not true for all worms — very important information if you are going to successfully treat a horse with worms.
In addition, not all worms can be treated with the same drugs – much like bacteria and antibiotics. And just as bacteria can become resistant to antibiotics, worms can become resistant to deworming medications. This has already begun the United States — particularly in the southern and eastern parts of the country.
With a limited number of dewormer medications and no new prospects coming on the market, there has been an initiative to begin testing the manure of horses more often to identify the type of worm eggs present and to provide the most appropriate treatment — just as would be done for bacteria and viruses. The method of treatment will remain the same but it will become more specific, and horses without worm eggs will no longer be uselessly treated, which will decrease the growing resistance problem.
The cost is quite low to have the test completed and it may save you money in the long run by not repeatedly deworming your horses.
Talk to your vet about fecal egg counts and find out the best way to treat your horse for longevity and success in the fight against intestinal parasites.
Chris Bell is an equine veterinarian and surgical specialist who operates Elders Equine Veterinary Service, with clinics in Cartier and Winnipeg. See www.eldersequineclinic.com.