11/18/2024
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THE OTHER WORMS
by Susan Schoenian
Sheep & Goat Specialist Emeritus
University of Maryland Extension
Small ruminants can be infected with many kinds of internal parasites, including different species of worms and protozoa. In fact, most small ruminants usually harbor mixed infections.
While most parasites are host-specific, sheep/goats get infected with the same ones (except for coccidia). In contrast, alpacas and llamas (often called camelids) can be infected with sheep/goat parasites, as well as those common to cattle.
By far, the most troublesome small ruminant parasites are the barber pole worm (Haemonchus contortus) and coccidia (Eimeria spp.). They are the most common, most pathogenic, and most costly. For this reason, they deserve the most attention. But, what about other internal parasites? How problematic are they?
Two other worms that are frequently part of mixed infections with the barber pole worm are the brown stomach worm (Teladorsagia circumcincta) and the black scour worm (Trichostrongylus spp.). While the barber pole worm causes blood and protein loss, these two mostly cause scours (diarrhea); production losses are more common than death. Unfortunately, it is not possible to differentiate the eggs of strongyle-type worms.
There are several other species of roundworms that may be identified in f***l samples from small ruminants. They include cooper’s worm (Cooperia spp.), hookworms (Bunostomum phlebotomum), nodule worms (Oesophagostomum), thread-necked roundworms (Nematodirus), threadworms (Strongyloides) and whipworms (Trichuris spp.). For the most part, they all have low pathogenicity and seldom cause problems.
Tapeworms (Moniezia expansa) are flatworms that usually cause much more concern than they should. It is because they are the only parasite that is visible outside the animal. While unsightly, tapeworms seldom cause problems. They don’t seem to affect nutrient absorption, and intestinal blockages are considered rare. Almost all research shows no benefit to treating lambs for tapeworms.
When animals cough or show labored breathing, some producers suspect lungworms. While possible, it’s not probable. The symptoms likely have other causes. Seldom do lungworms cause clinical disease in small ruminants. This is especially true with camelids and sheep. Lungworms tend to be more of a problem in wet, northern climates.
Symptoms of liver fluke are similar to the barber pole worm: anemia and bottle jaw. However, liver flukes are more common to cool wet climates, such as the Pacific Northwest and the Great Lake states.
One parasite that can be problematic on some farms is the meningeal worm (Parelaphostrongylus tenuis). Sheep, goats, and camelids are abnormal hosts for this parasite which naturally infects white tail deer. Small ruminants get infected when they ingest snails (or slugs) containing the larvae. Once the parasite crosses the blood-brain barrier, it causes various neurological symptoms.
If you think your animals are suffering from one or more of these other parasites, be sure to consult with your veterinarian. Diagnostic testing may be necessary. Not all of these parasites can be identified with traditional f***l exams. Sometimes, necropsies of deceased animals are necessary.
Published in the Delmarva Farmer, March 1, 2024
https://americanfarm.com/articles/delmarvafarmer/other-internal-parasites-shepherds-notebook/
