Caprine arthritis encephalitis

Caprine arthritis and encephalitis (CAE) is a viral disease of goats characterised by arthritis mainly in the carpel joints in mature goats (big knee), and by encephalitis in goat kids. Infected goats can also suffer from pneumonia, mastitis and chronic wasting. The infection is lifelong, untreatable and significantly affects productivity.

Cause

A retrovirus belonging to the subfamily Lentvirus.

Other names

Caprine retrovirus; CRV; Big knee in goats

Distribution in Queensland

Present in Queensland, mainly in dairy goats in eastern parts of the state. It has also been reported in the United States, Canada, Europe and New Zealand.

Life cycle

Most goats are infected when young through colostrum or milk from infected does. They generally develop the disease months or years after being infected. They remain infected for life.

Affected animals

goats

Hosts

Goats

Symptoms

The signs of disease vary according to the age of the animal. Effects can last several months.

Young goats

Symptoms in young kids may include:

  • encephalitis in young kids 2-4 months old
  • a short, stilted gait occurring suddenly, and progressing to arthritis and paralysis
  • pneumonia
  • hyperaesthesia developing, with convulsions and death.

Affected kids often retain their alertness and appetite during the early stages of the disease.

Mature goats

Symptoms in mature goats include:

  • depression
  • weight loss
  • changes to coat (becoming more rough)
  • mastitis
  • enlarged and painful joints, leading to lameness, incoordination and progressive paresis and paralysis
  • arthritis, generally in mature goats around 1-2 years old (but can occur as early as 4 months).

Some mature goats may also suffer from encephalitis.

Impacts

Economic

Economic impacts may include:

  • high cull rates
  • reproductive losses
  • milk production losses
  • animal deaths
  • loss of trade.

How it is spread

Most goats are infected when young through infected colostrum or milk from infected does. Once infected, the animal remains infected for life. Horizontal infection in a herd is possible through infected items at feeding and watering points etc.

Breeding and in utero transmission to fetuses are not considered risks because the virus does not cross the placenta and infected does give birth to normal kids. The birthing process can be a risk factor for infection if vaginal tears expose kids to blood.

People with contaminated hands, clothing and footwear can spread the infection into a herd.

Infection can happen at all stages of life, but kids are most at risk. The disease is generally slow to develop and infected animals could take months or years to show clinical signs.

Risk period

Infection can happen at all stages of life, but kids are most at risk.

Monitoring and action

Blood (serum) samples are required to diagnose CRV by an ELISA test or AGID test.

Only introduce goats from CAE-free herds, or have their blood tested before joining them to herd.

Remove all infected goats from the herd.

Remove kids from infected does at birth and keep them in isolation. Only feed them bovine colostrum and milk, milk substitutes, or milk from known CAE-free does. Kids affected by the disease should be humanely destroyed.

There is no successful treatment for infected animals.

Control

Biosecurity Queensland administers a voluntary CAE accreditation scheme.

The owner of a flock, with their veterinarian, is responsible for meeting the conditions of the scheme. Owners must meet all veterinary and laboratory costs and pay a fee to Biosecurity Queensland.

CAE scheme requirements include:

  • flock management and biosecurity
  • 2 negative blood tests of all goats over 6 months of age for initial accreditation (1 negative test if goats are purchased from an accredited herd)
  • annual or biennial re-accreditation (depending on the time of initial accreditation).

If the flock becomes infected, it will no longer be accredited until all reactor animals are removed from the herd and the flock is tested back to accreditation standards.

For more information, call the Customer Service Centre on 13 25 23.