Caseous Lymphadenitis (CLA)
CLA is a chronic disease caused by Corynebacterium pseudotuberculosis.
Symptoms include large masses around the head and neck associated with abscessation of lymph nodes. If these burst, they release highly infectious pus material. Internal abscessation in severe cases can lead to weight loss, reduced appetite and death.
Infection is by direct contact, by sharing troughs and via the environment.
Prevention is aimed at following good biosecurity measures and maintaining a closed herd or purchasing replacement stock from accredited herds. Purchased animals should be quarantined for 4 weeks and blood tested.
Caprine Arthritis Encephalitis (CAE)
CAE is a viral disease, closely related to Maedi Visna in sheep, spread predominantly via colostrum shortly after birth.
Symptoms include sudden loss of condition, painful and swollen joints (particularly the knee), or misshapen and hard udder. Diagnosis is via blood tests.
Prevention of CAE is similar to Johne’s (see above), by establishing herd status, removing infected animals, keeping a closed herd or buying accredited animals and good hygiene during kidding.
Johne’s is caused by Mycobacterium paratuberculosis avium, animals are infected early in life but do not show signs of disease until several years later. The bacterium targets the wall of the small intestine causing thickening and reduced nutrient absorption.
Symptoms include weight loss and poor performance. Unlike in cattle, diarrhoea is not a typical feature. Diagnosis requires a combination of blood test, faecal tests and post mortem examination.
It is spread via faecal contamination of the environment, during pregnancy from dam to kid, and via colostrum.
Prevention is by
· Establishing herd status via blood tests and removing infected animals
· Maintaining a closed herd or purchase replacements from accredited herds and quarantine for 4 weeks
· Ensure newborn kids receive sufficient colostrum that is not from infected dams (never feed pooled colostrum)
· Keep the kidding area clean with deep fresh bedding to avoid faecal contamination.