Our boxer loves all other dogs but his very best friend is a sweet female pitbull. They are about the same size and love to play. They are hilarious together. He is about 18 months old and although he is very mellow and well-behaved he csn be really wound up when he is playing. He even tries to get our cat to play with him. He tones it down for her because she is little-so he bites her ears and tail very softly.