Racer is a newly-rescued Queensland Heeler (Cattle Dog) who came in with a female Heeler, so we paired them in our kennel. Racer seemed to become so overstimulated in our kennel environment that he bullied the female, so we placed her separately. He was then kenneled with a female Doberman, and that didn't go well either. Racer may be able to live with another dog in a home environment that is less stressful, but he might also do better as the only dog. He's just a year old, and he's small, at 29 pounds. The folks at the vet clinic where we had him neutered said he was calm and well-behaved.