Why does my dog get distressed when we crawl on all fours?
Recently, my family and I have discovered that my dog appears to get distressed when we crawl around him, and starts whining but in an odd way and tries to bite our faces. I'm not sure what these whines mean, because he does not usually whine like that. I'm also not sure if maybe he's just playing (for example, he growls when we play tug-of-war), because he moves his tail (although I think this does not always indicate happiness and can mean other negative emotions as well, but I'm not sure) and doesn't bite hard enough to break the skin, but it does hurt. In addition, the second we sit up he stops. For additional context, he is an 8 month old border collie that's been with us since he was 2 months old.