369 VETERINARSKI ARHIV 75 (4), 369-374, 2005 * Contact address: Hisham Ismail Seri, P.O. Box: 32, Khartoum North, Sudan, Phone: +249 91284 7726; Fax: +249 183 575 644; E-mail: seri68@yahoo.com ISSN 0372-5480 Printed in Croatia Effcacy of Ivermectin in an injectable formulation against gastrointestinal nematodes of donkeys (Equus asinus) Hisham Ismail Seri 1 *, Adam Dawoud Abakar 1 , Ahmed Abdelrahman Ismail 2 , and Tigani Ahmed Tigani 2 1 Department of Clinical Studies, Faculty of Veterinary Science, University of Nyala. Sudan 2 Department of Pathology, Faculty of Veterinary Science, University of Nyala. Sudan SERI, H. I., A. D. ABAKAR, A. A. ISMAIL, T. A. TIGANI: Effcacy of Ivermectin in an injectable formulation against gastrointestinal nematodes of donkeys (Equus asinus). Vet. arhiv 75,369-374, 2005. ABSTRACT The efficacy of Ivermectin was evaluated under field conditions at Nyala town, South Darfur State, Sudan. The study involved 16 donkeys. Ivermectin was administered by intramuscular injection at dose of 0.2 mg/kg in the lateral mid- line of the neck. Treatment efficacy was based on the mean faecal egg count reduction 14 days post treatment. A faecal egg count reduction of 100% was found after treatment with Ivermectin. In addition efficacy percentages of Ivermectin against immature and adult nematodes were as follows: Trichostrongylus axei 100%, Parascaris equorum 100%, Oxyuris equi 100%, Triodontophorus sp. 100%, Strongylus sp. 100%, and small strongyles 100%. Two of the control donkeys were infected with Strongylus vulgaris larvae. Ivermectin showed moderate efficacy (69.23%) against larvae found in the mesenteric artery aneurisms. No adverse reactions were observed during the experimental period. Key words: Ivermectin, donkeys, gastrointestinal nematodes, efficacy Introduction Donkeys are becoming increasingly important animals in the Sudan given the new socio-economic situation with an increased use of donkeys instead of horses in labour and transportation. Nematode infection was the main problem reported in donkeys admitted to veterinary clinics (ALI et al., 2001). Ivermectin "ivomec" is a potent agent, active against