Yersinia is a bacteria that often causes diarrhoea in calves between 4 to 12 months of age. It is common after weaning followed by times of stress like adverse weather condition, transport, feed shortages and internal parasite infection. Affected calves cause heavy environmental contamination that can lead to infection in other animals. The main source of infection is via ingestion of faecal contaminated pasture.
Infection leads to damage of the intestine with a result of diarrhoea, poor growth and a stunted appearance. Infected animals might also look depressed and dehydrated.
The organism can be isolated from a faecal sample.
Tetracyclines (Bivatop, Engemycin) are the treatment of choice.
Control is by minimising the impact of stressors by improving management. Examples include decreasing mob size, feeding meal after transport, and weaning in good weather.