We've all seen dogs riding in the back of pickup trucks as the trucks fly down the highway. The dogs look to be having fun, but by living in the fast lane they risk injury from flying objects. Eye injuries are common, but there is an even greater danger: according to a California state legislator, approximately 100,000 dogs a year nationwide are killed because they jump or are thrown from a pickup. There's no reliable way of estimating how much damage and how many serious accidents such incidents cause.
Many local and state governments, and some states, now regulate how dogs can be carried in pickup beds. California, for example, requires dogs in the open back of a pickup to be either in a cage or cross-tied to the truck unless the sides of the truck are at least 46 inches high. The laws don't apply to cattle or sheep dogs being used by farmers and ranchers. Violators can be fined $50 to $100 for a first offense and up to $250 for a third offense. (Cal. Vehicle Code sections 23117, 42001.4.)
If you're worried about your dog bouncing around inside the car, or if you just want to keep it out of your way while you're driving, many pet supply stores and mail order companies sell seat belts and car seats designed just for dogs. There are also easy-to-install wire barriers to keep dogs in the "way back" section of a station wagon.
Parked cars. Dogs in parked cars are also at risk in hot weather; an enclosed car heats up in minutes, and the heat can kill a dog. Owners can be punished for leaving a dog in a car, under anticruelty statutes or laws that specifically forbid leaving a dog in a parked vehicle without adequate ventilation.