Yes they are.. but not exactly!!!!
Boers or any goats should be tested....if you have ever seen the results of a goat with CAE, then you would be in no doubt as to whether to test or not. The pain is excruciating when the goat/s develops the arthritis version....unfortunately it is maternally transmitted.
As a goat can have a lot of kids by the time she is 5-7 years old, the probablity is they will also be infected. If kids survive their 1st 12 months,.......encepholopy (spelling) is the first stage....then arthritis is the next stage later in life.
Testing started in 1983 in a desperate attempt to eradicate this dreadful disease..... succesful to a pont but something like 10% of the national herd is still infected..........mainly due to largeherds not testing and selling kids that are infected. Whilst the original Boers were clear when imported, they have been in contact with others that are not clear.
No responsible breeder will buy from a herd that is not regularly tested..... so you would limit your kid sales.
Speak to SAC who run the Premium Sheep & Goat Scheme, who will be able to advise you correctly about the dangers of running sheep & goats on the same holding.
By the way, testing is not as expensive as indicated earlier........typically Laboratory fees per goat are £7per test, more ten animals it comes down to around £6. Your Vet will have a cost of course, but people with a few often put them into a trailer and take to the surgery.
Be careful........ once you've got infected animals it is too late.