Theileria equi is a protozoan of the phylum Apicomplexa, transmitted by ixodid ticks and it is endemic in most tropical and subtropical areas of the world. The clinical signs in infected equines include fever, anemia, icterus, and in some cases death can occur. In June of 2011, 2 Arabian mares 2 and 8 years old were presented to the Veterinary Teaching Hospital, University of Shahid Chamran, Ahvaz, Iran with history of anorexia, depression, reluctance and difficulty to movement. Physical examination revealed petechiae in the ocular and vaginal membrane; sever jaundice, mild dehydration and many ticks in skin of the inguinal, perineal and armpit regions. The rectal temperature were 40.5˚C and 39.5˚C, heart rates of 88 and 64 beat /minute and respiratory rates of 60 and 72 per minute respectively. Respiratory sounds were increased in the both animals. No abnormality was detected in any limbs. Blood samples were collected by jugular venipuncture into a tube with EDTA as anticoagulant for haematological examination and blood smears were taken from upper lip for parasitology assay. Examination of the stained blood smears from the two horses revealed few parasitized red blood cells with T.equi. Both horses had sever anemia. Affected mares were treated with imizol (imidocarb),4mg/kgBW every 72 hours up to 3 times, phosphorus and Vit. B12. After one month, the mares were recovered completely.
With consideration to prevalence of Theileria equi in middle east countries and economic importance of this disease in horse farms and also the presence of infection in the Khuzestan province, a comprehensive epidemiological study is necessary for evaluation of Theileria equi prevalence and detection of carrier animals, thus the appropriate strategies for prevention and treatment of this disease can be down.
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