Gastrointestinal parasites of domesticated and feral horses (Equus caballus) in Sri Lanka.
Horses are not native to Sri Lanka. They are imported from neighbouring countries to be used for police work, sporting or riding and esthetic purposes. An isolated population of about 500 feral horses lives in the Delft Island in northern Sri Lanka. These feral horses served hundred years for western conquests and when they left Sri Lanka, horses were left behind in the Delft Island. There are no records of gastrointestinal (GI) parasites of horses in Sri Lanka and the present study was carried out to determine the GI parasites in the domesticated (free grazing and stabled) and feral horses. Fresh faecal samples were collected from horses and analysed qualitatively and quantitatively to determine the types of GI parasites and their prevalence and intensity. Qualitative analyses using direct saline and iodine mounts, simple test tube flotation, Sheather's modified sucrose flotation and sedimentation technique were carried out followed by McMaster counting technique for the positive samples. Identification of parasites involved morphological, morphometric and molecular methods. A total of 73 horses were sampled. All the feral horses (n=14) were infected. Among the domesticated horses, free grazers had a significantly higher prevalence of GI infections (46.7%) than the stabled ones (18.2%; Chi square test χ2=4.787, df=1, p=0.029). There was no significant difference between helminth and protozoan infections among the three groups of horses (Chi square test, χ2=1.453, df=2, p=0.484). Six species of parasites: Anoplocephala sp., Parascaris equorum, Strongylus sp. Isospora sp. Entamoeba sp. and Giardia sp. were recorded. Strongylus infections were recorded in all the feral horses with a high intensity but not in any of the domesticated animals. Strongylus is a highly pathogenic and the most damaging parasite of horses worldwide. It is important to investigate whether Strongylus infection is responsible for the high mortality recorded in the feral horses in the Delft Island especially because the Department of Wildlife Conservation is to declare Delft Island a National Park to conserve the feral horses.