The following technique can be used to introduce a new kitten or cat to your other cat(s). I have been involved in pet rescue most of my life and this technique has worked successfully every time. Over the years I have had to make some modifications when introducing older males or feral cats, but in most cases this will work exactly as described. It is assumed that your pet is neutered and the new pet is neutered or less than six months old.
Given a choice, you may want to follow a “wives tale” recommendation and choose a new young cat that is the opposite sex of your pet. For example, if you have a neutered male, select a female kitten or young female. If you have an older female, select a young male kitten. Many people believe that these combinations are the best options to ensure a compatible match. There is some biological support for this argument, but I have fused many same-sex and same-age cats and it has always been successful.
1. Before bringing home a new kitten or cat, make sure it is free of communicable diseases: feline leukemia, distemper, rabies, worms, and fleas. Most people avoid adopting a cat that has been exposed to Feline Aides, but there’s a mixed jury on how Feline Aides is spread. You may want to read up on this topic and form your own opinion before considering fusing an IVF-exposed cat with a healthy cat.
2. While the cats are still in separate quarters, feed them both a large meal. For example, give both cats a meal that is comparable to our Thanksgiving dinner; options include your favorite canned food, sardines, tuna, or chicken. Give them at least half an extra serving. You can also give her some natural soothing herb as a “Rescue Remedy”.
3. Place the new cat or kitten inside a cat cage about half an hour after the cats finish eating their big meal. Have a friend bring the new cat or kitten into your house and place the cage in the middle of the living room floor; make sure there is somewhere the new cat can hide once she is released from the crate (ie a couch). , meat, etc.). If you can’t find a friend, you can bring in the crate yourself, but you should ignore the new cat at all times.
4. Let your cats sniff and hiss at each other with your cat loose in your home and the new cat safely inside the cage. Since both cats are full and relaxed, it can take 20-30 minutes before the cats notice each other.
5. One hour after bringing the new cat inside, open the carrier door, but ignore both cats. Let the new cat out when he feels ready, this can take up to 30 minutes. Cats can still hiss and yell at each other, but it’s usually pretty minimal. Most of the time, the new cat will find a safe place to hide, such as under a sofa or chair. If the new cat runs towards you, ignore it.
6. For the next 3-4 days, you should ignore the new cat. Allow your cats to yell and hiss at each other as much as necessary. This allows your current pet and the new pet to establish their own pecking order. The only time you want to interfere is if the cats are fighting badly. If this occurs, throw a large amount of cold water on both cats and start the process over. (I once had to merge two sickly old male cats. Both had been “Tom” cats for years. After this hour-long fusion technique, they fought horribly. I broke up the fight with water, got a large dog cage, and for two days I rotated which cat was in the cage and which cat was loose. At the end of the two days, these cats got along very well.)
One final thought, you may want to start the introduction at a time when you can be home for a few days. For example, if you work Monday through Friday, you can combine the cats on Friday night so that you can observe them over the weekend.
