Johne’s Disease

Overview

Johne’s disease is a chronic, contagious bacterial infection of the intestinal tract in cattle, caused by Mycobacterium avium subspecies paratuberculosis (MAP). It spreads primarily through manure-contaminated feed, water, or colostrum/milk, and most commonly infects calves under 6 months of age — though clinical signs often don’t appear until 3years of age or older.

Signs

Chronic, watery diarrhea without blood or straining
Progressive weight loss despite normal appetite
Decreased milk production
Normal temperature (helps distinguish from other causes of diarrhea)

Why it matters

There is no cure once an animal is clinically affected.
Infected animals shed bacteria into the environment well before showing symptoms, making early detection and herd-level management critical.
Can have economic impacts through reduced productivity and culling.

Prevention & Management

Test and cull strategically to reduce herd prevalence
Manage calving areas to minimize manure contact with newborn calves
Feed colostrum/milk only from test-negative dams when possible
Maintain clean water and feed sources, away from manure runoff

Note

Ask us about herd-level testing options if you suspect Johne’s disease may be present in your herd.