Abstract
A survey was performed on the occurrence of some internal parasites in 461 horses (1–30 years old) slaughtered from October 1992 to September 1993 at the Linköping abattoir in central Sweden. Macroscopical examination was carried out specifically for parasites of the tear ducts and conjunctival sacs of the eyes, and of selected parts of the alimentary tract and car-dio-vascular system. The following parasites were found in selected parts of the large intestine: encapsulated cyathostome larvae (in 35.6% of the horses), and mature strongyle worms (17.4%); in the stomach: Gasterophilus intestinalis (12.3% during October-June) and Habronema muscae (1.1%); and in the conjunctival sac: Thelazia lacrymalis (3.1%). Significantly more encapsulated cyathostome larvae were found during January to June than during other times of the year, and horses aged 1–5 years harboured significantly more larvae than older horses. Severe damage to the cranial mesenteric artery and its main branches was noticed in 16 (6.1%) out of 263 horses specifically examined. However, the 4th stage larva of Strongylus vulgaris was only recovered in 6 (2.3%) of the horses. Quantitative and qualitative faecal egg counts were done on 412 and 384 of the horses, respectively. Eggs of strongyles, Parascaris equorum and Strongyloides westeri were found in 78.1%, 1.9% and 0.2% of the faecal samples, respectively. Highest prevalence of strongyle eggs was found during July to September. Third stage larvae of the following nematodes were recovered from faecal cultures: subfamily Cyathostomum sensu lato (78.1%) Triodontophorus spp. (6.5%), Strongylus vulgaris (3.6%), Trichostrongylus axei (1.3%), while Gyalocephalus sp., Oesophagodontus sp., Poteriostomum sp. and Strongylus edentatus each comprised less than 0.5%.
Keywords: equine, parasites, prevalence, relative density, mean intensity, Scandinavia.
Sammendrag
Förekomst och intensitet av styngflugelarver (Gasterophilus intestinalis), samt förekomst av vissa nematoder hos hästar i åldrarna 1–30 år undersökta vid slakteriet i Linköping redovisas. Undersökningen som var begränsad till att omfatta makroskopiskt synliga parasiter och parasitäre skador i magsäcken (n = 456), distala ileum, caecum och 0.5 m av proximala colon (n = 461), ögats konjuktivalsäck och tårkanal (n = 196), och krösroten (n = 263) pågick under tiden oktober 1992–september 1993. Hos de slaktade hästama påträffades larver av Gasterophilus intestinalis (9,9%) och Habronema muscae (1,1%) i magsäcken medan inkapslade larver av små strongylida maskar (35,6%) och vuxna strongylida maskar (17,4%) noterades i grovtarmen. Thelazia lacrymalis påträffades i ögonhålan hos 6 (3,1%) av hästama. Omfattande krösrotförändringar observerades hos 16 (6,1%) hästar medan intrevasala larver av Strongylus vulgaris däremot endast åtcrfanns hos 6 (2,3%) av de undersökta hästama. Hos merparten av de slaktade hästama genomfördes även kvantitativ och kvalitativ träckprovsundersökning avseende nematodägg. I den kvantitativa delen av undersökningen, som baserades på träckprover från 412 hästar, påträffades ägg av strongylider (78,1%), Parascaris equorum (1,9%) och Strongyloides westeri (0,2%). Efter kvantitativ undersökning inkuberades 384 träckprover för att möjliggöra artbestämning av tredje stadiets larver. Följande arter identifierades: gruppen Cyathostomum, sensu lato (78,1%), Triodontophorus spp. (6,5%), Strongylus vulgaris (3,6%), Trichostrongylus axei (1,3%), medan Gyalocephalus sp., Oesophago-dontus sp., Poteriostomum sp. och Strongylus edentatus utgjorde var och en mindre än 0,5%. Det visade sig att Gasterophilus intestinalis och Strongylus vulgaris numera är förhållandevis ovanliga parasiter hos svenska hästar sannolikt till följd av framgångsrika behandlingsprogram. Angrepp av små strongylida maskar utgör däremot fortfarande ett påtagligt problem.
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Acknowledgments
Financial support was obtained from the Swedish Horse Race Totalisator Board (ATG) and Agria Insurance Co, Stockholm, Sweden.
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