In-Focus Listeriosis in livestock

Listeriosis is a bacterial infection that affects many animals including humans. The disease is more commonly seen in sheep (most commonly), goats and cattle.

The gram positive bacteria, Listeria monocytogenes, are very resistant and can survive in the environment for a long time. They can replicate at temperatures ranging from 4 – 44°C. The bacteria is ubiquitous in the environment being found in soil, sewage, bedding, water and food –and replicates on poorly kept silage. Disease is more commonly seen in winter months when more silage is being fed.

Clinical signs – very varied:

Anorexia, depre s s i on and disorientation;

Propulsive behaviour – find them with their heads stuck in gates;

Head press into corners;

Circling;

One sided facial paralysis – drooping ear and lip, lowered eyelid, drooling; Infection is usually on one side of the brain, hence the onesided appearance; Impacted food in cheek due to paralysis of chewing muscles; Abortions – usually late gestation; Causes inflammation and infection of the placenta.

Diagnosis

Thorough clinical examination. If suspected in cases of abortion then dam blood, foetus and placenta need to be submitted for investigation as to the cause.

Treatment

Needs aggressive treatment with antibiotics. Higher than normal doses are required to allow crossing into the brain.

Supportive treatment with fluids and electrolytes will help those finding it difficult to drink and feed.

Control

Good silage management, make sure there are no holes in the wrapping (repair ASAP if there are any) and don’t feed any spoiled silage to the animals;

Make sure feed and water troughs are clean;

Avoid soil/faecal contamination of feed and water;

Addition of additives to silage to alter the pH and reduce Listeria replication; Fence off silage from farm stock and vermin to reduce damage to bail wrapping.