Dogs don't catch "colds" in the classic sense that humans do. Problem is, they do catch highly contagious kennel cough from other dogs. It's symptoms mimic most of those humans experience with colds. It is so contagious (between dogs, not dogs to humans) that our kennel won't accept dogs for boarding without a certifcate of health especially relating to kennel cough. It's easily treatable but only with antibiotics prescribed by your vet. Give him plenty of water and he'll be fine in a week or so... (Some dogs get some relief from one or two baby aspirin a day)...