So you've decided to open your home to a shelter cat. Congratulations! You have helped stem the cat overpopulation problem, and possibly saved the life of this cat.
It will be helpful to know what to expect when you bring him home. There will be a number of things to watch for, both physical and behavioral. The cat who seemed affectionate while in a cage may suddenly become shy, withdrawn, or even aggressive.

Careful pre-planning will help avoid many inherent problems.

Your Shelter Cat May Have Medical Problems

Because of the crowded conditions of many animal shelters, if is almost inevitable that your newly adopted cat will have one or more medical problems. It is important that you have him vetted prior to bringing him into your home, especially if there are other cats in your house. The best plan is to set the appointment with your veterinarian for the day you will pick up your cat. He or she may ask you to bring a fecal sample, and will want to see whatever medical records the shelter can provide. If this is your first cat and you do not have a veterinarian, the shelter officials can probably make a recommendation. Here are a few of the things your vet will check for:

• Parasites
  Fleas, ticks, and worms are common in crowded shelters. Ringworm, a zoonotic disease may also be found. If a fecal test discloses worms (most often roundworms or tapeworms), you will be given medication to rid the cat of worms, along with advice on treating the fleas with a bath and/or a topical flea control product.

• Test for Life-Threatening Diseases
  Many shelter cats lived rough on the streets, and may have been exposed to FIV (Feline Immunodeficiency Virus) or FeLV (Feline Leukemia Virus). You won't want to bring these disease home to other cats, so testing for them is of high priority. If the cat tests negative, you should discuss having him vaccinated against these diseases. Much will depend on the known history of the cat. If he was an indoor-only cat, he may not need the vaccines.
• Check for Other Communicable Diseases
  A larger percentage of cats in shelters carry the baggage of URIs (Upper Respiratory Infections). The most common are: Feline Panleukopenia Virus (Feline Distemper), Feline Calicivirus, and Rhinotracheitis (Feline Herpes Virus) The symptoms include runny eyes, sneezing, and an elevated temperature. By far, the most serious of these is panleukopenia, especially for young kittens. If your cat tests positive for any of these conditions, your veterinarian will discuss treatment options. If he gets a clean bill of health, he will be given vaccinations for these three diseases - these are called "core vaccines," and are recommended for all cats except the very old or very sick.
• Perform a Physical Exam
  While checking for the afore-mentioned conditions, your veterinarian will perform a complete physical examination of your new cat, including palpating his abdomen, and checking for lumps and bumps.
  He will then give the indicated vaccinations. If the cat has not been neutered, and appointment will be made at this time for a spay or neuter.
  

Bringing Your Shelter Cat Home

Your new cat has had a rough day already, and will probably be stressed by the time you bring him home. He is most likely used to the close environment of a shelter cage, so it would be best to keep him confined in a small safe room for the first few days, especially if there are other cats in the house.
Let your cat set the rules at first. Don't be surprised if the cat hides under the bed for several days. As long as he or she has food, water, a litter box, a place to sleep, and a toy or two, he will be okay. Chances are when you are not in the room, he will be coming out to eat, use the litter box, or explore.

Gradually increase your together time. Talk to your cat when you are in the safe room. You may want to sit in a chair and read a book. He'll come around when he finally feels safe with you, but don't rush it. Count your victories in small increments: the first time he peeks out at you from under the bed; the first time he plays with a wand toy with you; the first time he takes a treat you offer him. When he finally jumps up and settles in on your lap, you'll know that he is now your cat, and no longer a shelter cat.