Johne’s Disease is a chronic bacterial infection caused by Mycobacterium avium subspecies paratuberculosis (MAP) that affects the small intestine of goats and other ruminants. The disease can cause significant economic losses for goat farmers due to reduced milk production and weight loss. It is a challenging disease to manage due to its chronic nature and difficulty detecting it early. However, with proper preventive measures and early detection, Johne’s Disease can be controlled.
Johne’s Disease Management in Goat
Causes of Johne’s Disease
Johne’s Disease (JD) is primarily caused by Mycobacterium avium subspecies paratuberculosis (MAP), a slow-growing, acid-fast, gram-positive bacterium mainly affecting cow ruminants, sheep, and goats.
Occurrence of Johne’s Disease
- The bacterium MAP can survive in infected animals’ soil, water, and feces, making it easy to transmit from one animal to another. The most common transmission mode is ingesting contaminated food or water or directly contacting infected feces, milk, or other bodily fluids.
- Other factors that may contribute to the development of Johne’s Disease include genetics, stress, poor nutrition, and environmental factors such as overcrowding and poor sanitation. While there is evidence of a genetic component to JD susceptibility in some animals, the disease is not solely inherited and is not contagious among animals that are not infected.
Disease Cycle of Johne’s in Goat
Johne’s disease cycle in goats typically starts with ingesting MAP bacteria through contaminated feed, water, or milk. Once inside the goat’s body, the bacteria travel to the intestine and invade the intestinal wall, where they can replicate and multiply. Over time, the infection progresses, and the goat may begin to show clinical signs of Johne’s Disease, such as chronic diarrhea, weight loss, and reduced milk production.
Infected goats can excrete MAP bacteria in their feces, contaminating the environment, including feed and water sources, soil, and bedding. Other goats on the same farm can then become infected through direct contact with the contaminated environment or by ingesting contaminated feed or water. The disease cycle continues as the newly infected goats show signs of infection and excrete MAP bacteria, further contaminating the environment and potentially infecting other goats.
In addition to horizontal transmission from goat to goat, Johne’s Disease can be vertically transmitted from infected does to their offspring through infected milk or feces during birth. This can lead to young goats being infected with MAP early in life, resulting in more severe and chronic diseases. Overall, Johne’s disease cycle in goats is characterized by the continuous transmission of MAP bacteria through contaminated environments and infected animals, leading to the gradual spread and persistence of the disease within a herd.
Symptoms of Johne’s Disease in Goat
- Chronic wasting: This is one of the most common and characteristic signs of Johne’s Disease in goats. The animal may gradually lose weight despite consuming adequate amounts of feed, leading to a gradual decline in overall body condition.
- Pasty feces or diarrhea: In the early stages of the disease, goats may develop pasty feces or occasional diarrhea. As the disease progresses, diarrhea may become more severe and chronic, leading to dehydration and electrolyte imbalances.
- Hide and bone condition: In advanced cases of Johne’s Disease, the animal may develop a hide and bone condition, with prominent bones and a thin, emaciated appearance.
- Reduced milk production: Infected lactating goats may experience a decline in milk production or may stop producing milk altogether.
- The corrugated appearance of the intestine: During the post-mortem examination, the intestine of infected goats may have a corrugated appearance with thickened and folded intestinal walls.