Sherlock was adopted as a pup. He has had all his vaccinations (including his monthly heartworm). Neutered at 7 months. The vet estimates that his size a maturity should be medium (mother is medium-sized stray, father is unknown).
Sherlock is very playful, active and loves company. Unafraid of thunder or fireworks, and used to living outdoors. He isn't a noisy dog, but will bark at people at the gate. He was crate trained as a pup, and he holds his bladder overnight easily. He understands basic English commands (sit, stay, down, roll over, leave it, give, come, no).
We need to re-home him because he has grown too big for our small yard, and too exuberant for our young toddler and preschooler.
Can he be suitable as a guard dog?