changes in my black lab

Question
Hello, I have a 4 year old female black lab who is well trained and is the sweetest dog I have ever had. She has never been food aggressive with other dogs or people. The past couple of weeks when she has a bone and another dog goes next to her she barks,growls and lunges at them. A person can take it away from her without incident.
I used to take her to my grooming salon with me and she would love being around other dogs but 2 months ago my business partner adopted a standard poodle and now brings her to work and since then my lab has seemed depressed at the shop so I stopped bringing her. The standard poodle is aggresive when she plays with my lab. She slams her whole body against my lab and almost knocks her off her feet. It has been a week since I stopped bringing her to work and she seems much happier but she started with the aggression with other dogs when she has a bone. Can you please tell me what to do to make her stop? Thank you.

Answer
Is it possible that the rude poodle was taking stuff away from her? It's certainly possible that she she may have changed your dog's opinion about how "safe" other dogs are. Has she been guarding against dogs she knows, or dogs she doesn't know? Quite honestly, I don't consider protecting bones against another dog as true resource guarding (I would if a human was involved). It's survival instinct for dogs to keep what they have. Is she still fine with other dogs if resources aren't involved? I wouldn't make a big deal of it, but would be sure she gets lots of positive attention when other dogs are present, then possibly ignore her a little when they leave. So other dogs = good stuff. If you don't think she would become guardy about you, you could give treats when she sees another dog. If you are seeing other worrying details, I'd go to the vet, get bloodwork done including a 6 panel thyroid and a check for tick borne diseases. Sudden changes in behavior sometimes have a physical cause. If it was my business partner, I'd be talking with her, about possibly bringing dogs on alternate days, or crating and not allow the two dogs to "play" together since it's obviously not a good game to your girl. Sandy Case MEd CPDT www.positivelycanine.com