Here is my 2 cents for what its worth....
DOGS can be carriers of Strep! When my son didnt seem to be getting better after being 100% and going down hill, I had a gut feeling that my dog was an issue. I had my dogs throat cultured under anesthesia. My gut was RIGHT. She had culture positive STREP in her throat! She had no symptoms. We treated her for 10 weeks total. About 5 days into treatment my son got back to 100%! IMHO if you can give all the abx and IVIG in the world to your child, but if fido is a carrier and sleeping with your kid, its not going to work. After the one dog got diagnosed I treated all my dogs (and my cats on my own). If you are looking for a cause talk to your vet. get a dog cultured. If one hasit, they probablly all do, so treat all of them. If you are broke, and cant afford to have your dog put under, then explain
the situation to the vet and see if they will do treatment without the culture. I have to be honest. I had never done a culture of a dogs throat in my vet tech experience. Even the vet I knew looked at me funny when I asked her to do this. But she said it was possible. Its reverse zoonosis. We(humans) give the bacteria to the dog and they carry it. Its no different than if your spouse was a carrier. They can also be rectal carriers. I am not saying that you should get rid of the pets. But be aware, investigate mention it to the doctors your children see. I am happy to talk to anyone further including docs, vets, etc. (not that they want to talk to a lowly tech) I plan on sharing this with all PANDAS doctors. Some are aware including the NIH, but I think they need to get on this issue