Fred puts Barney in hypnosis to make him act like a dog but there are no dogs in The Flintstones. Characters have dinosaurs (such as Dino) as their house pets. Barney wouldn't have seen a dog and not known what a dog looks or behaves like.
After Barney was picked up and put in the Dog Catcher's vehicle, (to be taken to Bedrock's dog pound) his truck is motorized. The driver's feet aren't on the ground and you can hear a real motor run.