dagney's mom said:
my one year old male boxer has been really aggressive at his day care. he goes 2 or three times a week and according to the people there, he "goes after" certain dogs. he has never bitten another dog, but they say that he lunges at them and does the aggressive fence bark.
Did they tell you what they do? He's an adolescent boy and he's being obnoxious, but that's fairly common behavior, and people entrusted to care for multiple dogs at a time should know what behavior is a sign of worse things to come, and what's just adolescent idiocy that can be curbed.
Do they put him in a time out? Spray him with water? Walk over and interrupt the behavior and tell him to knock it off?
Like people, sometimes dogs just don't "like" certain other dogs. A good daycare will have a rotation system by which dogs that don't play nice together play separately with different groups of dogs.
It's for this reason I would never leave my dog in a daycare that just leaves everybody loose all day. There needs to be a way to have gentle playtime for the older/slower/shyest dogs, rambunctious playtime for energetic adults and rowdy adolescents, etc. If dog A and dog B don't get along, it's not the end of the world -- they can still have plenty of playtime without having to deal with each other. If they're both solid citizens and play well with other dogs, it's not a generalized aggression issue and they shouldn't be worrying the owners about it, nor should they allow it to continue.