Instructions
Rub a clean cloth along the kitten's cheeks to take up its individual smell. Let your adult cat sniff it and watch how he reacts. If he is relaxed and curious, take it as a good sign. If he flies into a rage you know for sure that this particular kitten is not for you. Then rub your cat's cheeks with the same cloth and let the kitten sniff it. Observe the reactions. Do this several times until the scents of both cats mingle.
Prepare your home with "Feliway" diffusers. Feliway is a pheromone that makes cats feel secure. On the day the kitten arrives, place the diffusers strategically all over the house to keep stress to a minimum. Put the cat carrier with the kitten in front of your established cat and, again, watch the reactions. If both appear curious and friendly, brilliant. They will most likely become friends very quickly and you can let them play together, supervised at first. Give your adult cat lots of extra attention and treats. This way he won't feel jealous and associates the kitten with something pleasant.
Introduce them more gradually if your tomcat is less than impressed. Put the kitten up in a secluded room with food, water and a litter tray. Continue to take its scent with a cloth from its cheek and rub the adult cat with it. Feed him treats while you do so. Also take scent from your adult cat and rub the kitten with it. Eventually, both of them should get used to each other's smell. Scatter a trail of treats to the door of the kitten's room. While your tom gobbles them up, he will learn to link the kitten to a nice experience. Keep this routine up for two to four weeks.
Leave the door to the kitten's room slightly open and give both cats the opportunity to sniff each other. Reward them with lots of treats and cuddles, especially your adult tom. Supervise them during the first contact. Have some fishing-rod style toys ready to deflect stress. Observe the interaction closely. If the cats show signs of aggression or stress, end the playing session, give both cats treats and cuddles and repeat the session the next day, until they relax in each other's company. Eventually, they should get used to each other.
Provide separate food and water bowls as well as litter trays in various locations in the house. As a rule of thumb, you'll need a litter tray for each cat plus one. So if you have two cats, you need three litter trays. Only if the cats really love each other, you might get away with having only two. Give them lots of space, high resting places and hiding holes to optimize the chance of a peaceful relationship between the members of your cat family.
How to Introduce a Kitten to an Adult Male Domestic Cat
Like people, every cat has a unique personality. Whether the introduction of a kitten to an adult cat will be successful depends on the individual character traits of each. So there are no guarantees. The cats' gender is rather unimportant. If anything, it should be easier to introduce a new kitten to a male adult, especially if he has been neutered. Male cats are more placid than females.