Here in Seattle there are many families who have a four legged family member. Dogs are everywhere, and the city is very dog friendly. While many parents research for hours about how to restrain their child in the car, most do not do the same for the family pet.
The same laws of physics apply to the dog. Weight time speed equals force. If you have a small dog who sits on your lap, your body (say a 180 pound man at 30 mph is 5,400 pounds of force) will slam against the dog. You’ll stop, but the dog will continue into the windshield, or be crushed between your body and the airbag.
If you have a larger dog who is kept in the way back, say a 100 pound dog (that’s 3,000 pounds of force in a 30 mph collision), it’s unlikely the headrests will hold the dog back. Everything in a collision moves toward the point of impact. So if you are hit from behind your dog will slam toward the back hatch, maybe out the back window. If you are hit on the front your dog will head toward your baby, you, and the windshield. Your baby, who is secured properly in a seat in the middle of your backseat, will suddenly have 3,000 pounds of dog on their lap. Or maybe the dog will bypass the baby and hit the back of a front seat at 3,000 pounds of force.
A dog has as much risk as anything else not held down to be ejected. Driving around town, the sight of a dog’s head out the window is a well known sight in Seattle. How easy it would be for the dog to sail straight out the open window. The dog is then at risk of being hit by other vehicles, run over by your own, or injured from impacting the roadway or other debris.
So how should man’s best friend ride in the car? Harnesses are made that work the same way as carseats. They adapt a seatbelt made for the average size male to fit a four legged creature as best as they can. The dog wears the harness, the seatbelt goes through a holder on the harness. Some harnesses can use the LATCH system, or have adapters so they can be used with cargo hooks in the way back.
What about the furry feline friends? They too should be restrained. Most cats ride in the car infrequently, and in a crate, but in a collision that means the weight of the cat plus the weight of the crate to consider. If the cat is small enough, a soft crate in the footwell of the passenger or a backseat will work very well. The cat will be contained within the small space (other than in a rollover). If multiple cats are traveling at once or the crates are larger, there are adapter kits for the seatbelt that can be purchased. Some crates have beltpaths for the seatbelt built in. Using bungee cords in the way back is also an option.