Ovine Johne’s disease is a granulomatous enteritis caused by infiltration of the intestinal tract with Mycobacterium avium subspecies paratuberculosis (MAP).
SRUC VS recorded 837 diagnoses of Johne’s disease in sheep between 2005 and 2019, with wasting being the most common presenting sign. The condition was confirmed in 37 different breeds plus eight crosses.
The number of diagnoses fluctuates throughout the year with few in the summer months. Peaks in February and September are associated with the investigation of thin ewes that are barren at scanning, and thin ewes that fail to gain condition after weaning.
Advancing gestation, and seasonal nutritional constraints, may contribute to the higher number of diagnoses in late winter.