I once drove from San Diego, California, to Milwaukee, Wisconson during a very hot summer in an old van with two other people and a wonderful cat named Ollie. Although Ollie tried hard to be the perfect co-pilot, he really had a hard time on that week-long trip. When the temperature goes up, lots of us fled to the shore, and why shouldn't our pets come along for the ride? Road trips with animals require a lot of planning, but they can be done with minimal stress to both people and pets if you have all the necessary tools.
Taking your cat on a short car trip (5 hours or less) usually isn't too big of a pain. Make sure they have a carrier that can be strapped into the seat belt just in case you have to make a quick stop. Try to get them comfortable with the carrier prior to the trip. Most cats do fine in a soft-sided (mesh) carrier, but if your cat is especially persistant, you may want to get a hard-sided (plastic) carrier to prevent them scratching their way out. DO NOT LET YOUR CAT RUN LOOSE IN THE CAR WHILE DRIVING. Cats are slinky creatures, and would love to curl up underneath the brake pedal when you least expect it. Cats can get car-sick, and often show stress by throwing up, pooping, or peeing where they shouldn't. Be prepared for this - have a washable or disposable bed in the carrier. We stock both types of carriers, as well as washable beds.
If you're planning a longer trip with a kitty, it gets a bit more involved. I recommend investing in a cat harness and leash in addition to the carrier, so that you can give kitty some (safe) leg stretching time. You'll need a litterbox, scoop, and bags for the ride as well. You can close all the doors and windows of the car and let kitty out of her carrier at rest-stops to use the litterbox. (Make sure you supervise and leave the air conditioner on!) Be sure to plan out pet-friendly hotels if you spend the night! We stock cat harnesses and leashes, small litterboxes, etc.
Like cats, dogs should be safely restrained in the car. My favorite doggy seat belt is the Ride Right Seat Belt Connector because it attaches right to the dog's normal harness, can be left in the car at all times, and gives the dog a little bit of room to wiggle while still keeping them safely in their seat. Some dogs do better in a crate. Bringing along a special chew (such as a bully stick) can help keep them busy and calm them down during the trip. Don't forget your harness, leash, and poopy bags so that your pup can relieve themselves at rest stops! Like cats, dogs can get carsick and vomit, pee, or poop where they shouldn't due to stress. They can't help it! Don't get mad, instead be prepared for this, and make sure your car is protected.
Happy Traveler, Calming Chews, and the Thundershirt are all natural calming aids that help animals cope with the stress of traveling. These can be life savers for a stressed-out pet. The Water Rover is great for making sure you can easily offer your pet water during the trip.
NEVER leave a pet in a hot car. Not even with the windows cracked. Not even for 5 minutes. Just don't do it.
Make sure you pack for your pet. Along with leash/collar/harness, food, water, bowls, medications, a favorite toy, blanket/bed, grooming needs, and vet records (just in case) are a good place to start. If your pet isn't sensitive to food changes, the Honest Kitchen dehydrated foods are great for trips because they don't take up much room, are easy to rehydrate, and can tempt stressed pets to eat when they otherwise wouldn't.
Anytime your pet leaves the house, for any reason, make sure they have a collar with ID tags attached. A tag with your phone number may make the difference between a lost pet finding their way back home or being lost forever!