An outbreak of bovine thromboembolic meningoencephalitis in Yucatan, Mexico

Seventeen Beef-Master cattle (three calves, one male and thirteen cows) died within a period of two months with neurological signs. A neurological syndrome was evident in the patients characterised by ataxia, incoordination, dysmetria, hyperacusia, muscle tremors and ptyalism. A dysfunction of trigeminal, facial and vestibulocochlear cranial nerves was also observed. At necropsy a septic process was evident. Histopathology of internal organs showed necrosis as a consequence of septicaemia. Complete blood cell count showed leukocytosis due to neutrophilia, lymphocytosis and monocytosis. Macroscopically the brain showed severe congestion and the histology showed a thromboembolic meningoencephalitis and thickening of the meninges. To stop the outbreak, oxytetracycline was provided to the entire herd for 10 days and all susceptible animals vaccinated against Histophilus somni . No other case was presented until a month later when two cows and one calf died with the same symptomatology. Immunosuppression was associated with the development of the disease.