Generally dogs and cats may be left alone for 3 or 4 days at a time as long as you provide them with enough food and water to last them the duration of your trip. Exceptions would include any animal that requires medication, a pet on a special diet that needs scheduled feedings, or an animal with behavior problems. For whatever reason, if you will not be able to leave your pet alone during your trip, you still have several options.
The first option, and probably least stressful to your pet, is to have a friend or relative stop by your house and attend to the pet's needs. This is also the best idea if you have more than one pet that you are leaving home. Of course, you should find someone that you trust with your home, and that your cat feels comfortable with, as well. If you use a pet-sitting service, check out their references thoroughly and meet personally with your sitter before making your decision. They should belong to a professional pet-sitters organization (such as PSI or NAPS) and be licensed if it's required where you live. Be sure to leave your number and your vet's number in case of an emergency, instructions for bad weather, and make sure they know the exact steps you want them to follow as far as feeding your cat or administering medications. Most importantly, if you don't feel comfortable with the person or the care they will give your animal, find someone else. The peace of mind during your trip, and the well being of your pet, will be worth the extra effort.
Another option would be to take your pet to someone else's home while you're away.
If you decide to do this, make sure the person is familiar with your animal and vice versa. If there are any other animals in the home, will they get along? Are the other animals healthy, and spayed or neutered (yours should be!)? And make sure you bring along the food that you pet is used to, as a sudden diet change can stress or even be unhealthy for your cat or dog. A favorite toy or bedding material will also help ease the transition for your pet. When you leave, don't make a big deal out of it. A hug or kiss and a promise to be back will let your pet know it's not being punished and that there's nothing to be upset about. And if you travel often, try to use the same person as your out-of-home sitter so you'll all feel more comfortable with the situation.
Kennels are being used more and more now, and with proper inspection, can be a fine place for your pet to stay while you're away. When picking out a kennel, ask a vet or friend if they can recommend a good boarding place for your pet. Then go and check it out. Look for a clean (including the smell), quiet kennel with staff that pays attention to the boarders. Again, you should get a feeling of whether the employees actually enjoy taking care of the animals, or if your pet will just be put away in a cage and fed daily. Ask if you can contact some of their clients. And before checking in, make sure your pet has had all its vaccinations (some are even required by kennels) and is in good health.
Now, say you DO want to take your pet along with you on the trip. If you're staying with friends or relatives, make sure your pets are welcome before you go. Make sure you have kept up on all your pet's vaccinations, and even some extra ones (for example, a Lyme disease inoculation if you'll be going camping or hiking). Proof of vaccination may be required at some hotels or kennels. ID tags are a must when traveling, and you may want to take along a recent photo, just in case. Here are some guidelines for the various ways of travel:
Animals shouldn't be allowed to roam free inside moving vehicles, especially cats. If you have a well-behaved dog that follows verbal orders, then it may be alright for shorter trips. Always have a carrier or crate available, though, as animals can be unpredictable. Cats and small dogs should be put in carriers on the back seat, while larger dogs may need to be crated or fenced in the rear compartment of a station wagon, van, or SUV. You may find that certain types of carriers (for example, soft or hard types) may calm your animals down more once they are inside. A carrier should always be of the appropriate size for your animal, and should have a mat on the bottom for comfort, cleanliness, and to prevent sliding around when the car moves. There are also seatbelt like harnesses made for dogs that you may want to try, but they won't offer the security of a crate or carrier. A leash should always be used when taking your pet out for a pit stop, which should be made frequently.
Provide a travel, no-spill water dish in the carrier or available often for your pet. You may want to keep a large supply of water from your house, to minimize risk of illness from drinking new water (maybe consider this for you, too). Feed your pet only small amounts at a time on long trips.
In the summer, make sure your pet is kept in an air-conditioned part of your vehicle and has shade to retreat to if necessary. NEVER LEAVE YOUR PET ALONE IN A HOT VEHICLE. EVEN WITH THE WINDOWS DOWN. EVEN WITH THE WINDOWS DOWN AND YOU'LL BE RIGHT BACK. NEVER RIDE WITH YOUR DOG IN THE BACK OF AN OPEN BED TRUCK. I DON'T CARE IF IT'S YOUR HUNTIN' DOG AND HE LIKES IT, DON'T DO IT. It is also recommended that you don't let your dog ride in the car with its head out of the window. If the window is only partly open, they may get their head stuck or hurt their neck if you have to stop suddenly. If the window is open all the way, you never know when your dog may try to jump out. And finally, I'm sure you've seen drivers flick lit cigarettes out of their windows -- you don't want these, or even the ashes, hitting your dog in the face. This is why a dog shouldn't hang its head out of windows, and why they should not sit in the back of open bed trucks.
Not all trains will allow pets (other than disability/service dogs) inside their passenger cars, but rather treat the animal like luggage. This is not a good thing. Often animals are placed in cold (or hot), unsecured parts of the train with no fresh air. Check the policies before booking your reservation.
Some airlines are more pet-friendly than others. There are numerous horror stories of negligence toward animals being transported by plane, and many pets have been lost this way. If possible, I would always suggest looking for an alternative to flying with your animal. If it's the only option, though, here are some tips:
Always make sure your pet is in the best of health, and has documentation from your vet to prove it. This will be necessary with most airlines. While at the vet, you may wish to discuss the use of tranquilizers if your pet has a behavior or medical problem that may necessitate them. Note: This is just information, not a recommendation. I would never use tranquilizers on an animal unless it's absolutely necessary.
Some breeds should never be taken on a plane. Short-nosed breeds, like the Pekingese or Boston Terrier dog, or a Persian cat will not be able to withstand breathing the hot air often found in animal cargo areas.
Cats may often be carried in a small carrier that can be kept under your seat. But there is usually a "one cat" limit on this, so any other animal will need an appropriately sized traveling crate to ride in the pet area. Pet areas are pressurized, like the passenger cabin, but temperatures and air quality can't be guaranteed. Check up on your airline's history of following correct pet procedures before putting your pet on board. Mark the crate clearly with your name, address and phone number (home and while traveling), the animal's name, and another contact person. Make sure you tell the flight attendant/pilot that you have an animal on the plane.
Always get a direct flight when traveling with animals. Direct is not the same as non-stop. You can minimize other delays by traveling at off-peak times or seasons. Also consider the temperatures of the areas you will be traveling in/through. Avoid extremes -- anything out of the 50-85 degree range.