Equine Pinworm PDF

CLINICAL PATHOLOGY I - Lecture Equine Pinworm Oxyuris equi  Another nematode; named for long, tapering tail  Ubiquitous -- especially in areas of high rainfall  Affects horses and donkeys worldwide Life Cycle  Direct  Transmission = F...

CLINICAL PATHOLOGY I - Lecture Equine Pinworm Oxyuris equi  Another nematode; named for long, tapering tail  Ubiquitous -- especially in areas of high rainfall  Affects horses and donkeys worldwide Life Cycle  Direct  Transmission = Fecal-oral  Prepatent period = 5 months  Males ~ 1 cm long; females ~ 15 cm long  Adult worms in cecum and colon  Gravid females migrate down GI tract to perianal area, lay eggs in sticky clusters.  Eggs cemented in clumps to anus and surrounding area with yellowish-gray, gelatinous material (8,000 to 60,000 eggs per clump)  Eggs become infective in 3 – 5 days; cement dries and flakes off.  Flakes containing ova attach to stall walls, feeders, fences, and bedding, contaminating environment  Eggs licked off or fall off and ingested with grazing  Eggs hatch in small intestine, larvae pass to cecum and colon to complete maturation  Eggs resistant to drying and viable for long periods of time Clinical Signs  “Pruritus ani”  Irritation due to “cement” used to attach eggs o Perianal irritation and ulceration o Tail head rubbed raw o “Rat-tailed” appearance Oxyuris equi ova  Not found in feces taken directly from colon May be found in feces collected from ground  Characteristics of O. equi ova o Ovoid and yellowish o Slightly flattened on one side o Mucoid plug (operculum) at one end Diagnosis  “Scotch tape method”: Examine microscopically for ova  Fecal float a poor technique  Presumptive dx with perianal itching  May observe adults passed in stool Treatment  All broad-spectrum equine anthelmintics effective against both immature and adult pinworms o Ivermectin, moxidectin 12/3/2024 1  o Fenbendazole, oxibendazole o Pyrantel 12/3/2024 2