Osseous cyst‐like lesion of the intermediate humeral tubercle of a horse

sis) has been estimated to vary from 10 to 91 per cent in cattle (Sayin and others 1994, Eren and others 1995). It has been suggested that cattle with tropical theileriosis commonly present anaemia in addition to fever, swelling of the lymph nodes and rapid loss of condition. The anaemia that occurs in theileriosis is probably caused by extravascular haemolysis (Hooshmand-Rad 1976, Lal and Soni 1985). Although severe anaemia progresses in cattle with theileriosis, unlike in babesiosis, haemoglobinuria rarely occurs (Lal and Soni 1985, Morrison 1998). In this case, the calf showed slight decreases in packed-cell volume, haemoglobin and red blood cells, indicating that it was suffering from a mild anaemia. It has been suggested that serum indirect bilirubin and iron levels in cattle with theileriosis are remarkably elevated during severe anaemia (Hooshmand-Rad 1976, Watanabe and others 1998), but this was not observed in the present case. It has been reported that clinical signs of cerebral theileriosis include ataxia, depression, circling, head pressing, hyperaesthesia, blindness, hypermetria, nystagmus, proprioceptive deficits and aggressiveness. When the disease is fatal, the animal becomes recumbent and develops opisthotonos, tonic clonic seizures and coma (Saville 2002). In this case, the calf presented signs of ataxia, hyperaesthesia, blindness and tonic clonic convulsions, which were easily induced by stimulation. The nervous signs occur as a result of vasculitis and lymphocytic inflammation of the brain (van Rensburg 1976, Khanna and others 1982, van Amstel 1982). Capillary engorgement, scattered punctuate haemorrhages on the surface of the brain, thrombosis of the meningeal vessels, haemorrhage in the cerebral ventricles and infarctions of the splenic vessels have been reported as postmortem features of the cerebral form (van Rensburg 1976, Khanna and others 1982, Bader and others 1986, Saville 2002). Although T annulata causes high mortality in cattle, recent studies have shown that buparvaquone is highly effective in the treatment of affected animals (Morrison 1998, Saville 2002). The present case demonstrated that the prescribed treatment was also successful in controlling the nervous form of the disease. Studies based on conventional techniques suggest that the cerebral form of theileriosis is caused by Tannulata, Theileria parva and Theileria taurotragi (De Vos and others 1981, Saville 2002). This case also demonstrates that T annulata is a cause of cerebral theileriosis. Further studies using PCR to determine the types of Theileria responsible for the cerebral form of the disease will be useful for differential diagnoses.