Inside the Equine Tapeworm
Tapeworm Species
Anoplocephala perfoliata
Anoplocephala magna
Paranoplocephala mamillana
Three species of equine tapeworm affect the horse. Anoplocephala perfoliata is by far the most prevalent and is of the most concern to horse owners. Anoplocephala magna and Paranoplocephala mamillana, however, do occur elsewhere in the world but are rare in the United States.
Tapeworm Characteristics
The tapeworm belongs to a class of parasites known as cestodes – unlike roundworms and strongyles, which are nematodes. Tapeworms have a simple body structure, composed of a scolex, which attaches to the intestinal wall of the horse, and many proglottids, or body segments, each of which contains reproductive organs and eggs. The tapeworm receives nutrients through its tegument – its absorptive outer layer.
Anoplocephala perfoliata
Anoplocephala perfoliata is the most abundant and infective of the equine tapeworms. It usually measures about 1 to 3 inches in length and has a rounded scolex with four hooks that allow it to attach to the horse’s intestine.
Tapeworm Eggs
The very nature of tapeworm eggs makes diagnosis of their presence extremely difficult. Tapeworm eggs occur in very small numbers, and many times they exist in packets rather than as individual eggs. The excreted tapeworm eggs don’t float well in traditional fecal floatation tests, which means they evade veterinary detection quite easily.
The Ileocecal Junction
Anoplocephala perfoliata tend to congregate on the surface of a unique area in the horse – the ileocecal junction. This spot is the common opening between the ileum, or small intestine, the colon and the cecum, the pouch that is the beginning of the large intestine and serves as a kind of fermentation vat.
To get a better understanding of the tapeworm’s life cycle and how it affects the horse, let’s take a look at the anatomy of a normal horse.
An Indirect Life Cycle
All tapeworms have an indirect life cycle; they need an intermediate host in order to complete their life cycle. Equine tapeworms use an extremely common, tiny, pasture-dwelling insect for this purpose – the oribatid mite. These mites are very small, and they’re found in virtually all soils all over the world.
Let’s take a closer look at how this mite helps the tapeworm complete its life cycle, keeping horses infected for long periods of time.
To learn more about the inside of the equine tapeworm, click
here.
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