Caprine Arthritis Encephalitis (CAE) or Caprine Retro-Virus is a chronic, slow-viral disease of goats which poses a significant risk to Australia’s developing goat meat industry, particularly as there is currently no treatment or vaccine for the disease.
The goat industry as a whole needs to be concerned about controlling and eradicating CAE to avoid production losses and potential market access issues for live goat exports, particularly in relation to dairy goats.
What is CAE?
CAE is a viral disease which may take years to present. Typical symptoms include:
- Arthritis especially of the carpal or knee joints;
- encephalitis or inflammation of the brain with nervous signs, especially in kids, but sometimes in adults;
- general wasting and ill-thrift;
- chronic mastitis with the udder becoming very hard and producing very little milk; and
- chronic and progressive pneumonia, which affects the tissues between the air sacks in the lungs.
Due to the slow progress of the disease, asymptomatic or carrier goats are common. The disease is most often first detected in association with a doe’s first kidding due to the physiological stress associated with that event. The onset may vary with the viral load in the goat herd: the greater the number of goats excreting virus, the sooner clinical signs may appear, and visa versa.
There are no known health effects of CAE for humans.
How is CAE spread?
The CAE virus attacks the goat’s immune system and may be spread by any bodily fluid, particularly semen, milk and colostrum. Once a goat has contracted the CAE virus, it is infected for life.
Due to its potentially devastating effects on goat production, The World Organization for Animal Health (OIE) requires every country to report annually on CAE and uses this information to map the global incidence of CAE. Unfortunately, Australia is mapped as having the disease in all states. The OIE also requires all international exports of dairy goats to be serologically tested for the disease.
CAE is less common in under-developed countries and most native breeds are free of the disease, unless they have come into contact with infected imported animals, usually dairy goats.
Europe is making progress in eradicating CAE through culling and some countries have CAE free zones.
Different risks for different herds
CAE is more common in dairy goats than meat and fibre goats, as dairy goats are more frequently exposed to goats’ milk via leaking udders and are managed at higher densities. Milking machines are also known to spread CAE. This does not mean that meat and fibre goats cannot develop CAE, but to date, cases have been rare.
The stud dairy goat industry is aware of CAE and official CAE accreditation is available from Departments of Primary Industries/Agriculture or breed societies in most, but not all states. These schemes are based on whole herd blood testing and visual veterinary inspection. Visual inspection is essential as goats with severe clinical signs of CAE may have reduced CAE antibody levels, making detection through blood testing more difficult.
Meat and fibre goat producers are less aware of the risks of CAE; however, in Canada and the US, there has been a drift of CAE into goatmeat herds over recent years resulting in significant production losses so these sectors should not be complacent.
What should goat producers do?
All goat producers must ensure they have a rigorous and practical biosecurity plan for their property and herd, which considers the following:
- How to identify CAE and deal with affected animals to prevent infection of the rest of the herd;
- always source any new goats from accredited CAE-free herds, especially dairy goats;
- always source goats’ milk from accredited CAE-free herds, especially if it is to be fed to kids; and
- never introduce (or reintroduce) meat bucks into meat herds if they have been to be used in dairy herds for mating, unless they are accredited CAE-free dairy herds.
What does the industry need to do?
CAE can be eradicated. The wider goat industry must encourage the dairy goat industry to control and eventually eradicate CAE through rigorous biosecurity plans and eradication strategies. In the meantime, goats from dairy herds should be kept separate from all other goats, unless they are from accredited CAE-free herds. This includes running separate goat shows and sales and carefully managing bucks.
For more information about CAE, the following are good resources: