@Quercus:
And just as an another perspective…I instruct all visitors to our house to ignore the dogs...because although the human may LOVE dogs, or be great with dogs, or whatever, they are still strangers to my dogs. And my dogs (or any dog) may not appreciate a stranger singing to them, or massaging them, or whatever. I understand that the home health care staff is different than strangers, per se...but still...the dog may wish to have some boundaries with non-family humans. That being said, it is unacceptable for the dog to show his displeasure about strangers,or their behaviors by biting them
+1 to this - I was thinking the same thing that perhaps he wanted his space, but also agree that biting isn't acceptable. I am adamant that visitors to my house ignore the dogs (not even look at the dogs). If I have people come over that I know or suspect won't ignore the dogs, the dogs are crated or put outside to run. I have one b-kid that does not like to be approached by strangers - she prefers to make the first overtures. Since I want to set her up for success, I don't put her in a situation that could go wrong.
The other thing I was going to say was about it being "breeding season". I do have one intact boy that nibbles people (usually preceded by intense sniffing) when it is that time of year. He does it to me and to my brother - but I put the kibosh on it when it happens (it feels like a pinch when it happens, but it definitely isn't a bite or breaks skin). During breeding season, he definitely isn't out of the crate (unless in the yard) when visitors are over because I don't want them to mistake his nibbles for bites. However it sounds like since Kipawa broke skin, it might be more than a nibble.
Good luck with everything and let us know what you figure out.