Pneumonia due to pasturellosis causes mortality in Brahman cows in Katherine

In August, a private veterinarian investigated mortality in a group of 180 Brahman cows which had recently been transported to a property in the Katherine region. Over a two-week period approximately 50 cows had shown signs of nasal discharge and coughing, and 30 had died.

On clinical examination the affected cattle were having trouble breathing, with heavy breathing rates and nasal discharge. A single three year-old cow was euthanised and post-mortem examination revealed liquid in the lungs, as well as the lung sticking to the thoracic wall.  Examination of lung tissue under the microscope revealed a severe pneumonia, consistent with Mannheimia haemolytica infection. There was no microscopic evidence of viral involvement, and a heavy growth of M. haemolytica was cultured from lung samples. A diagnosis of pneumonic pasturellosis (shipping fever) was made. While shipping fever usually involves infection caused by P. multocida in cattle, it may also be caused by M. haemolytica in the absence of P. multocida. It is likely that the recent stress of mustering, long-distance transport and yarding resulted in the high morbidity and mortality in this case.  This level of pneumonia is an infrequent situation in northern beef herds.

Vaccines are commercially available for the main respiratory viruses and bacteria that contribute to BRD, including IBR, BVDV and M. haemolytica. The vaccines are not widely used in Territory, but should be administered prior to entry into the feedlot and mixing of cattle – a process known as ‘backgrounding’.

Last updated: 30 April 2020

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