Verminous encephalitis in a horse produced by nematodes in the family protostrongylidae.
Authors: Tanabe M, Kelly R, de Lahunta A, Duffy M S, Wade S E, Divers T J
Journal: Veterinary pathology
Summary
# Editorial Summary Protostrongylid nematodes are an underrecognised threat to equine neurological health, as demonstrated by this landmark case of a six-month-old Arabian colt presenting with verminous encephalitis affecting the cerebellum and broader central nervous system. Histopathological examination revealed granulomatous eosinophilic inflammation alongside eggs, larvae, and adult nematodes consistent with *Parelaphostrongylus tenuis*, characterised by distinctive dorsal-spined larvae; notably, this represents the first confirmed protostrongylid infection documented in equine literature. The presence of viable parasitic stages within neural tissue indicates that these nematodes—typically associated with cervid and camelid hosts—can establish aberrant infections in horses, potentially via consumption of contaminated forage or intermediate gastropod vectors. Clinicians should consider protostrongylid infection in the differential diagnosis of juvenile horses presenting with progressive neurological signs, particularly those with access to pasture shared with or previously occupied by deer or other wildlife reservoirs. Further epidemiological investigation is warranted to establish whether this represents a genuine emerging risk or an isolated case, but awareness among veterinary professionals and grazing management strategies merit attention.
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Practical Takeaways
- •Protostrongylid nematodes should be considered in differential diagnosis of CNS disease in horses, particularly young animals presenting with neurological signs
- •This parasite may be acquired through consumption of intermediate hosts (gastropods/slugs), making pasture management relevant to prevention
- •Veterinarians should be alert to this emerging or previously unrecognized diagnosis in equine neurological cases, particularly in regions where wildlife reservoirs exist
Key Findings
- •First definitive report of protostrongylid nematode infection (family Protostrongylidae) in a horse, affecting a 6-month-old Arabian colt
- •Parasitic infection located in cerebellum with presence of eggs, larvae, and adult nematodes causing granulomatous eosinophilic inflammation
- •Nematode characteristics compatible with Parelaphostrongylus tenuis, a parasite previously not documented in equine CNS