Caprine retrovirus (CRV) is a serious disease of goats. It was formerly known as caprine arthritis encephalitis or CAE. Its common name has been "big knee".
CRV occurs only in goats. It causes arthritis, encephalitis and pneumonia. Arthritis occurs in mature goats, mainly involving the knees, but sometimes other joints. The joints become enlarged and painful (hence the name of the disease "Big Knee"). The condition is chronic and steadily gets worse. Affected goats become lame, have a rough coat and gradually lose weight.
Encephalitis affects young kids two weeks to five months old. It shows as lameness, incoordination, progressive paralysis and finally death. This form of the disease has only rarely been seen in Tasmania.
Pneumonia is seen in some infected goats, mainly adults. These show respiratory distress and loss of weight, and progressively become worse.
There is no response to antibiotics with any of these forms of CRV.
Transmission of Infection
The main method of spread is from doe to kid via the milk or colostrum, so that kids are infected soon after birth.
Some spread of infection occurs by contact between adults especially in intensively managed herds, such as occurs with dairy goats. The disease is less common under extensive grazing conditions used for meat and fibre production and feral goat populations.
CRV affects production and can limit export markets. Understandably, interstate and local buyers want evidence of freedom from CRV.
A voluntary, user pays CRV control scheme with a register of CRV-free
herds kept by DPIPWE on behalf of the industry has been available to Tasmanian
goat producers since 2011. As no herds have registered since its instigation, DPIPWE
no longer manages this register. Goat
producers interested in CRV control are encouraged to access the National Kid
Rearing Plan on the Animal Health Australia web site (http://www.farmbiosecurity.com.au/industry/goat/)
and consult with their local private veterinarian.