Hi, Jean. As to testing in smaller herds, I can only share my experiences. Two Saanen dairy goats I got from a CAE-prevention farm, and I trusted the seller, so didn't test. One yearling doe and kid I got for a bargain (!!!) and didn't feel comfortable about, she was thin, licey, had unkempt hooves, and I had her tested and I quarantined her. The kid died, after being at the vet, and the Nubian was CAE +.(posted 8952 days ago)The six Angora goats I got this year I quarantined, and tested and all were CAE neg.
Better safe than sorry. I will also bottle all the kids, even though they have been tested, as CAE prevention. Also, my vet believes that CAE is often spread across (not vertically from mother to kid, but to other goats) by healthy animals stepping in and eating near the placenta and goo from kidding. Good luck!