Peer-reviewed veterinary case report
Horse with chewing muscle atrophy due to nematodes
By Eckert, Johannes & Ossent, Pete·Published in Veterinary parasitology·2006·Institute of Parasitology·View original on PubMed →
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Original publication title: Haycocknema-like nematodes in muscle fibres of a horse.
- Species:
- horse
Plain-English summary
A 14-year-old horse that had been living in Switzerland for the past eight years showed signs of muscle wasting in its jaw. After taking muscle samples for testing, veterinarians found that the horse had a severe long-term inflammation of the muscles caused by a large number of immature and mature female nematodes (a type of parasitic worm). Most of these worms were found inside the muscle fibers of the jaw, tongue, and chest, while only a few were located in the spaces between muscles. Although the worms were different from a known type that affects humans, they resembled a recently identified species called Haycocknema perplexum. This case suggests that different types of nematodes can invade horse muscle fibers and cause inflammation.
Abstract
A 14-year-old horse (imported to Switzerland from Ireland 8 years earlier) showed signs of chewing muscle atrophy. A severe chronic myositis, caused by numerous immature and mature female nematodes, was diagnosed in muscle samples obtained by biopsy and subsequently at necropsy. Most of the nematodes had invaded muscle fibres of the masseter, root of the tongue and anterior breast, only a few were found in the intermuscular interstitium. Isolated nematodes and parasite sections were clearly different from muscle larvae of Trichinella spp. but showed morphological similarities to Haycocknema perplexum, a nematode species (order Enoplida, family Robertdollfusidae) recently found in the musculature of a human patient in Australia. However, our material did not allow the precise identification of the nematode genus nor the unequivocal differentiation from Halicephalobus gingivalis. This species infects horses and humans and can cause severe granuloma formation in muscles and many other organ systems, but has never been observed to invade individual muscle fibres. Our findings show that nematodes of another genus than Trichinella may invade muscle fibres of the horse and cause myositis. These nematodes are provisionally regarded as Haycocknema-like.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/16616813/