Protective Labrador retriever

Question
I have a 3 1/2 year old female yellow lab and we recently adopted her full brother, a 6 month old now lab.the two of them get along wonderfully.  When other dogs play or approach her brother, she growls at them.  She never growled before.  Perhaps she's over protective of him. This seems to be happening even with dogs that she knew before he came along.  Any suggestions?

Answer
Likely you are right, she is protecting him.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

If you are a strong leader and welcome the other dogs, she should follow your lead.