I think I have a dog with kennel cough. What should I do?

If you even suspect the dog has a kennel cough, you must immediately visit a vet. Look up some youtube videos to see what Kennel cough looks like/sounds like.

Kennel cough is transmitted by air. So keeping dogs separate is key. However, they've been with the suspect dog already so if the dog has KC, then they're probably going to as well. However, I don't believe spitting up white foam has anything to do with kennel cough. Dogs with KC make a hacking noise. The white foam may indicate that the dog is trying to vomit something up.

First off, you need to deal with the suspect dog. It needs to be seen by its vet. If you truly think it may have KC, the vet will prescribe meds but KC usually just runs its course of about two weeks.

If it is definitely KC, then the other dogs' owners need to be told. It would be irresponsible not to do so.

My vet told me that dogs will sometimes spit up white foam when struggling with kennel cough.