It may be hard to understand the significance of tapeworms in horses. The infection caused by these worms in horses is somewhat hard to diagnose.
Tapeworms in horses, for many years, have been found associated with postmortem examination of the animal’s intestinal tract. Infections caused by these parasites went unnoticed since it is hard to detect them in fecal egg tests and clinical symptoms were not clearly associated with the parasite infection.
However, recent studies have shown that equine tapeworms pose as a great risk factor for spasmodic colic as well as impactions occurring at the terminal end of the horse’s small intestine. Several studies have also demonstrated that there is a high percentage of infection caused by these parasites. This leads to an interesting subject on tapeworm threat to horses, once considering to be a minor threat, wrong!
Different Species of Tapeworms
There are three species of tapeworms that cause infection in horses namely Anoplocephala magna, Anoplocephala perfoliata, and Paranoplocephala mamillana, with A. perfoliata as the most common species found in horses. P. mamillana is considered a rare species to be found in horses. A. perfoliata is described as having a short, triangular body that could either be yellow or green in color. The mature worm can grow from 3-8 centimeters. Those that are smaller than that size range may either be an immature worm or another species, specifically P. mamillana. Common equine tapeworms, A. perfoliata, use four suckers to attach themselves to the intestinal lining of the host, where they would compete for nutrients through their cuticle.
Diagnosing Tapeworm Infections
As mentioned, it may be difficult to diagnose tapeworm infections. Most tapeworm infections are not accompanied by clinical symptoms, but can cause damage for a period of time before signs of disease become visible. Heavy infestation though could lead to anemia and unthriftiness while modern grade infection may just carry on without producing visible signs.
Tapeworm eggs are also the reason why diagnosing the infection is difficult. They congregate in small numbers instead of as individual eggs. These eggs don’t really float well when in a testing medium, which makes them easily unnoticed during a fecal egg count analysis. To be able to visualize tapeworm eggs, there is a need to perform more sophisticated examinations. Most of the veterinary labs are not well-equipped to perform such tests, so as a result, diagnosing the infection is missed. However, there are instances where a parasite specimen can be detected in the feces of an infected horse once a they have been administered with a deworming agent that works best against tapeworms.
Venturing the Life Cycle of a Tapeworm
Tapeworms are considered different from other equine parasites because they have an indirect lifecycle. In this type of life cycle, an intermediary host will be needed for the parasite to develop -in the case of A. perfoliata, an orbatid mite. This certain mite must be living in order to be a qualified host, and they are found in pastures and even hay or straw.
The tapeworm egg goes through cellular division inside the orbatid mite; then it becomes a larva. It would take about 12-15 weeks for this process. The mites that harbor the infective larvae are unintentionally ingested by a horse that grazes freely in pastures. Then, the tapeworm infection will result. The larvae will develop inside its primary host- the horse – and will develop to maturity. These worms begin to shed segments that support the eggs in about 6-10 weeks. There is not much influence brought by seasonal changes on how many horses will be infected or how great the infection will be.
Tapeworms in horses reside in clusters around the ileocecal valve found in the intestinal tract, just by the junction of the large and small intestines. This particular small region is where changes in the intestinal tract is done by tapeworms. Until recently, not many studies have been performed to analyze the damage brought about by tapeworms.
The Damage Caused
Once, tapeworms were thought to be harmless but recently, they have been found to cause severe damage in the intestinal tract of the horse. With tapeworms, colic and decreased intestinal motility result.
It is quite difficult to tell when to give a horse an anti-tapeworm regimen, not until the common tapeworm is better understood. Generally, treatments to address tapeworm infections should be administered every 6 months. The treatment is ideally given in the fall and repeated during late spring. More focus should be directed on how tapeworms become a major contributor for colic in horses. These tapeworms are associated with some types of equine colic. Though it may be a small association, it is something that horse owners should be avoiding.
Consult your veterinarian on the possibility of tapeworm infection in your horse so that the best treatment regimen for controlling these parasites in horses can be given. It is better to prevent the infection from getting worse, than end up paying hefty veterinary bills when it is already too late!