Prevalence of selected species of internal parasites in equids at necropsy in central Kentucky (1995–1999)

Abstract

A survey to determine current prevalence of several species of endoparasites in equids ( n=350) at necropsy was conducted at the Livestock Disease Diagnostic Center in central Kentucky (1995–1999). Thelazia lacrymalis were found in 42% of the 1- to 4-year olds ( n=132), which was the only age group examined for these parasites. Five- to 30-year olds ( n=157), examined for Onchocerca spp. worms/lesions, had a prevalence of 24%. In ≥1-year olds ( n=324), the infection rate for Gasterophilus intestinalis was 12% for second instars and 14% for third instars and for Gasterophilus nasalis was 2% for second instars and 2% for third instars. For Anoplocephala perfoliata ( n=268 equids), prevalence was 52%. Data were compiled for the equids according to breed, age, sex, month of necropsy, and number of parasites. Arterial lesions caused by migrating Strongylus vulgaris larvae were observed in a low number (3 of 52) of equids. Specific examination for Parascaris equorum revealed that 46% of 13 weanlings and 10% of 20 older horses were infected. Anoplocephala magna were found in one of the weanlings. Compared to previous studies (about 15–25 years ago) in Kentucky, the present survey indicated the genera Onchocerca and Gasterophilus greatly declined but Thelazia, Anoplocephala, and Parascaris did not.