Listeriosis
Listeriosis is a common neurological disease in sheep, particularly in adult sheep during the winter and spring months. It is caused by the bacterium Listeria monocytogenes, which is often found in spoiled silage. This bacterium can also be present in soil and the gastrointestinal tracts of mammals, making it a persistent threat in certain environments.
Symptoms and Diagnosis 🩺
Encephalitis
The most recognizable form of listeriosis in sheep is encephalitis, which affects the brain. Symptoms can appear rapidly, often within 24-48 hours, and include:
- Anorexia and depression
- Disorientation and circling behavior
- Facial paralysis on one side, leading to a drooping ear, flaccid lip, and lowered eyelid
- Profuse salivation and difficulty eating
- Propelling into corners or leaning against objects due to weakness on one side of the body
Diagnosis is typically based on clinical signs, but can be confirmed through post-mortem examination of the brain.
Other Forms
Listeriosis can also cause abortion in pregnant ewes, septicaemia in young lambs, and eye infections known as "silage eye".
Treatment 💊
Early detection and aggressive treatment are crucial for recovery. Treatment typically involves:
- High doses of antibiotics such as penicillin or ampicillin
- Supportive care, including fluids and electrolytes
- Anti-inflammatory medications
The recovery rate can be up to 30% with prompt treatment, but severe cases often result in death despite intervention.
Prevention 🛡️
Preventing listeriosis involves good management practices, particularly with silage. Key steps include:
- Feeding high-quality, well-fermented silage
- Discarding spoiled or contaminated silage
- Minimizing soil contamination during silage production and feeding
- Regularly cleaning feed troughs and discarding uneaten feed
Additionally, ensuring that silage bales are properly wrapped and stored can help prevent contamination. Pregnant women and individuals with health risks should take extra precautions when handling silage, as listeriosis is a zoonotic disease.