I have two lab puppies, a brother and sister who are now about 8 and 1/2 months old. I had them both "fixed" (neutered and spayed) about 10 days ago. The surgeries went fine, and one week later the vet gave me the green light to take off their cones (Elizabethan collars) and let them return to the park, and today we can return to the beach.
So we have been going to the park for off-leash runs the last 4 days, just was we did before my boy puppy was neutered. Before he was neutered, he was aggressive towards another dog only once -- his brother, who visited our home one time for a supposed reunion, but who tried to eat some food sitting on the counter. My puppy harassed him so badly that my assistant, who has him, had to take him away. Otherwise, my boy puppy was NEVER, EVER aggressive towards other dogs, but always playful with them and with his sister.
But he would sometimes stray while off leash and blatantly ignore my commands to the point where it had become a serious problem.
Since he was neutered he has become OBVIOUSLY MORE AGGRESSIVE. In four days he has attacked or picked on four different dogs, typically smaller female dogs.
There has been no biting, but today was the worst: He had a female dog by the throat and would not let go until two of us pulled him off!
He never did this before. I need to establish more leadership and train him much, much better, but this has happened to us too, and I am very, very concerned. He is a Lab, 8 months old. What happened to the other fellow's dog who became more aggressive?
I would really appreciate any help that anyone can provide. Thanks.