Johne’s is caused by Mycobacterium paratuberculosis avium, animals are infected early in life but do not show signs of disease until several years later.
The bacterium targets the wall of the small intestine causing thickening and reduced nutrient absorption.
Symptoms include weight loss and poor performance. Unlike in cattle, diarrhoea is not a typical feature. Diagnosis requires a combination of blood test, faecal tests and post mortem examination.
It is spread via faecal contamination of the environment, during pregnancy from dam to kid, and via colostrum.
Prevention is by
- Establishing herd status via blood tests and removing infected animals
- Maintaining a closed herd or purchase replacements from accredited herds and quarantine for 4 weeks
- Ensure newborn kids receive sufficient colostrum that is not from infected dams (never feed pooled colostrum)
- Keep the kidding area clean with deep fresh bedding to avoid faecal contamination.