Educational Tips for Farmers: Johne's Disease (JD) or Paratuberculosis in Sheep and Goats

Johne’s disease (JD) is a wasting disease caused by the bacteria Mycobacterium avium paratuberculosis (MAP), which can be zoonotic.

Life Cycle

• MAP enters the body when the animal ingests bacteria shed through feces, colostrum, and milk.
• Infection with MAP causes the small intestine to swell. This immune response prevents the animal from absorbing nutrients.
• JD progresses through four stages.

Stage I. Silent, subclinical, nondetectable infection

• No clinical signs
• Undetectable in a blood test
• No shedding

Stage II. Subclinical shedders

• No clinical signs
• May be detectable in a blood test
• Small amount of shedding in feces

Stage III. Clinical disease

• Weight loss
• Detectable
• Large amount of shedding in feces

Stage IV. Emaciated animals with fluid diarrhea

• Emaciation, dehydration, intermittent diarrhea
• Detectable
• Extreme shedding in feces

Signs

• Chronic weight loss despite a normal appetite.
• Exercise intolerance.
• Decreased production.
• Diarrhea and submandibular edema (“bottle-jaw”; more common in cattle than in small ruminants).

Diagnosis

• Most often diagnosed at necropsy.
• Enlarged intestinal lymph nodes and thickened intestinal wall.
• Bacterial culture and blood tests.
• Not very accurate in small ruminants.

Prevention and Control

• Avoid manure contamination.
• Don’t give lambs/kids colostrum from a JD-positive ewe/doe.
• Maintain a closed herd.
• Conduct annual blood testing.
• Testing is especially important when a positive animal is found in a herd.
• Blood tests are the most accurate way to diagnose JD in an animal.
• Cull infected animals.
• Till the pasture; MAP can live on the ground for up to 1 year.

Treatment Plan

• Immediately isolate the animal.
• Wear PPE such as gloves to avoid contamination.
• Euthanize the infected animal.
• Perform a necropsy to confirm JD diagnosis.
• Properly dispose of the animal and all items that had contact with it.
• Follow the prevention and control protocol and monitor the flock/herd for signs of JD.
• Always consult a veterinarian if an animal is suspected of having Johne’s disease.

M2507 (POD-04-26)

By Harlea LaFrain, Bachelor of Science Graduate; Lindsey Dearborn, Master of Science Graduate; Leyla Rios, PhD, Assistant Professor, Animal and Dairy Sciences; and Michael Pesato, DVM, Four State Veterinary Services.