Comparison of Tolerance to Theileriosis in Different Breed of Cattle by Evaluation of Clinical Signs and Response to Treatment

　 reducing production and death. The disease in endemic areas would be mild or subclinical in indigenous cattle and clinically acute in exotics. OBJECTIVES: This study was conducted to evaluate the resistance of indigenous cattle in comparison with Holstein and crossbred cattle against Theileria annulata through assessment of clinical signs and response to treatment. METHODS: For this purpose, the data history and clinical examination were observed on 51 naturally affected cattle with T. annulata (17 Holstein, 17 crossbred and 17 indigenous cows). Examination of blood smears was used for diagnosis. Detection of schizonts in lymph node punctured smears confirmed validity of the suspect samples. All three groups of cows were treated with buparvaquone along with oxytetracycline. Their clinical signs and the results of blood smear examinations were recorded before and 48 hours after treatment. The severity of clinical signs, parasitemia rates and response to treatment were compared among the groups. RESULTS: The results showed significant difference (p <0.05) in severity of fever, intense and abnormal lung sounds, mucosal changes (pallor, jaundice, petechiae) and ruminal hypomotility among the groups. There was no significant difference in parasitemia rate and response to treatment among the groups. CONCLUSIONS: This study indicated that Iranian indigenous cattle in comparison with Holsteins and crossbreeds had milder clinical manifestations and no significant difference in response to treatment for tropical theileriosis.