Parasite control for horses has been simplified over the past decade with the introduction of do-it-yourself paste dewormers. Today, parasite-eliminating drugs such as ivermectin, benzimadozole and pyrantel are all readily available over the counter.
Pfizer's revolutionary new horse dewormer Strongid C, a pyranted tartrate product brand that is fed daily, was introduced five years ago.
Despite demonstrated effectiveness, some have voiced concerns about Strongid C.
Pyrantel tartrate continuously kills parasites in the horse's gut before larvae can damage vital organs and long before adult worms can develop, says Pfizer. A daily deworming program, they say, eliminates confusion over timing, treatments and dosage.
As with any horse dewormer, there are questions about effectiveness, safety and resistance. Veterinarians have been keeping a cautious eye on pyrantel tartrate, although several studies and practicing veterinary experience indicate that the product is working as it should. "STRONGID C represents an innovative and unique alternative to parasite control that was previously not available," explains Robert Dressler, Pfizer's senior equine technical service veterinarian. "Pyrantel tartrate, the active ingredient in Strongid C, is a potent dewormer that effectively kills the major adult and larval parasites inhabiting the gut of a horse."
Dressler maintains that because Strongid C is given to your horse daily, it not only kills parasites before their larvae do damage, but, also "since few adults live in the gut of treated horses, Strongid C continuously reduces the production of worm eggs and greatly diminishes the degree of parasite exposure that would normally result from eggs shed onto the pasture."
Strongid C is the first preventative deworming program for horses, Dr. J. C. Downing, another Pfizer veterinarian, points out. Previous programs were designed for treatment and control. Strongid C actually prevents parasitism instead of viewing it as chronic disease to be treated every once in a while.
Strongid C has no action against bots and onchocerca. To control these horse parasites, Pfizer recommends using ivermectin at least twice a year in addition to Strongid C. "Use ivermectin in late fall or early winter, and again in the spring, "says Downing.
Is it worth it to the horse owner to spend the money on Strongid C, since ivermectin paste is needed as well?
Pfizer's Dressler says yes, explaining that Strongid C provides round-the-clock control of parasites, unlike paste dewormers, which tend to purge out of the horse's system.
"Horses are maintained in a manner that is conducive to parasite development," Dressler says. "Therefore, the prevalence of parasites and their impact on horses is intensely magnified. Without consistent parasite control, horses are vulnerable to the detrimental effect of parasitism."
While conventional purge anthelmintics are effective in removing worm burdens at the time of treatment, Dressler says they do very little to affect the overall consequences of parasitism. Conventionally treated horses are immediately susceptible to parasite reinfection once the anthelmintic has been cleared from the horse's system. And that can be just a few hours, or at most, a few days.
Will Strongid C protect your horse if it's in a pasture with other horses that either aren't treated or are treated periodically?
According to a Pfizer study, mares that were treated with the pyrantel tartrate had reduced numbers of parasite eggs; mares treated with bi-monthly paste deworming of ivermectin, pyrantel pamoate and oxibendazole showed an increase in egg counts at six weeks.
Controlling horses parasites with Strongid C isn't cheap -- at least not at first glance. Cost estimates run to about $15 per 1,000-pound horse per month. However, Dressler says the cost-effectiveness of Strongid C comes in "keeping the parasite burden and inflammation down. This makes the gut more efficient and the need for feed is reduced by 10 to 15 percent."
Strongid C is a unique product that lends itself to debate. Many veterinarians and horse owners have found it a useful tool in the war on parasites.
Is it 100 percent effective? No, but no dewormer is.
Is it cost-effective? Many horse owners swear by it.
If you have had problem horses, it may be worth considering as an addition to your deworming arsenal. Remember, no one deworming product of program will work for every situation. As always, discuss options with your veterinarian, and follow all label directions carefully.