When New Pet Meets Old Pet

By Ann Smalley

Susan was heartbroken. At first, getting the little kitten to keep her other cat, Whiskers, company had seemed like such a good idea, but it obviously wasn't going to work out. From the first moment Susan had brought Tibs into the house and shown him to Whiskers, Whiskers behavior had been just awful. He had hissed and growled at the little newcomer and scratched Susan. Even worse, although Whiskers had been housetrained for years, Susan found a puddle on her bed that Whiskers had left, and then Whiskers, a neutered male, started spraying in the house. Susan sadly decided Tibs would have to go back to the shelter.

Pet owners may find this story all too familiar. Most of us who love animals like to have more than one around -- for some, the more the merrier. But it can be difficult to introduce a new pet into a household where there are already cats or dogs. Fights, behavior changes, and housetraining mistakes are all common consequences of upsetting the status quo. Too often, pets adopted from shelters as "company" for resident pets find themselves back at the shelter because "they just didn't get along." In some cases, the second pet is adopted to help "cure" the resident pet of bad behavior, perhaps barking or chewing. When this effort fails, both animals find themselves without a home.

When a new pet is introduced into a household, a period of stress and adjustment is inevitable for both humans and animals -- but there are ways to help make the transition a little easier on everyone. What kind, sex, and size of new animal you choose to bring home makes a difference, and how you stage the initial introduction is also important. Your own behavior for the first few weeks will influence how the resident regards the interloper, whether as friend or foe. For this reason, if you're considering adding another pet to the family, it's important before you bring home Number Two, Three, or Four to assess the situation, and decide if you're ready to cope with the problems that might arise.

People acquire more pets for many reasons. They love them and like having them around. They want to do the best thing for a pet they already have and get another one to keep the first one company while away at work all day. An abandoned animal at a shelter wins their hearts and they know they can't say no to him. And there are advantages to having more than one pet. Dogs love company, and having a companion can cut down on destructive or annoying behavior. Cats may play together and amuse themselves while left alone for long periods. But getting a second pet as company for the first does not mean that the animals will require less time from people. All companion animals need to develop and enjoy strong bonds with people, so another animal actually means a larger time commitment from the owner.

Someone considering bringing home another pet should also be aware of the potential problems that may develop. The introduction of a new animal is always going to be stressful for a resident pet, and stress has a way of finding an outlet. In dogs, it may lead to fighting, housetraining mistakes, and jealous behavior.

Cats may also fight -- even cats that have been best buddies for years. They become more susceptible to illness and disease when under stress. Cats, too, may become unhousetrained, and, in some cases, direct aggression towards their owners, as well as towards the newcomer.

Animals are extremely territorial and need enough space to call their own. Problems may arise from, or be aggravated by, forced proximity. Is there enough money to pay for vaccinations, veterinary care, food, toys, and all the other expenses of owning a pet? Every pet adds a little more responsibility.

If one has made the decision to add another pet, there are ways to stack the odds in favor of easier acceptance, fewer problems, and more harmonious multi-pet relationships. Some combinations are more likely to succeed than others. The best scenario is to start with two from the beginning. Littermates are ideal, either puppies or kittens. (Puppies require a bigger time commitment, for housetraining and later training.) Getting a puppy and a kitten at the same time is good, too, although a very small kitten could be harmed by a rambunctious puppy. A good time to introduce the puppy to the household is when the kitten is about six or seven months old and better able to defend itself and teach the puppy some manners.

When introducing a new pet to an already established resident animal, the less threatening the newcomer is, the better the chances he will be accepted. To animals, non-threatening means younger, smaller, and usually a different sex. For instance, a seven-year-old spayed female cat would probably feel intensely threatened by another adult female, even if he were also spayed. Chances that the two would ever get along are slim. On the other hand, she would probably accept a male kitten, who would pose no initial threat and would be young enough for the older cat to "train." Keep in mind, however, that a youngster can be very stressful on an elderly pet, since animals, as they age, become increasingly less able to cope with change.

Animals also tend to get along better when they are all spayed and neutered. Dr. Randall Lockwood, Vice President for Training Initiatives at The HSUS and a nationally known expert on canine behavior, notes, "Male aggression is fairly familiar, but I have also seen intact female dogs be extremely aggressive towards other intact females. Since territorial and dominance behaviors are affected by hormones, spaying and neutering naturally reduce these aggressive impulses."

Timing is also important. Since introducing a new animal is stressful to the residents, it makes sense not to do it at a time when they are already under stress -- when they have just moved to a new house or apartment, for instance, or when one is recovering from an illness or injury. Cats, in particular, are very routine-oriented; they like things done in the same way, at the same time, every day. Any disruption in their routine is stressful, so it's wise not to add the stress of a new animal at the same time a cat may be feeling stressed from another cause. This can work to an advantage, too; keeping to a familiar routine can help reassure a resident cat and help minimize the stress of the newcomer's presence once the animal is in the house.

The decision is made -- or perhaps it was made for you when those big brown eyes looked into yours. However, although you've arrived at the decision to bring home another pet, your first responsibility is to the ones you already own. You must protect their health. Make sure their vaccinations are up-to-date; take them to the veterinarian for boosters, if necessary. The newcomer must have all his shots, be dewormed, defleaed, if necessary, and kept in quarantine, either at the veterinarian's or at a foster home, for two weeks, which should be enough time for any infectious diseases to appear. Once he is certified in good health, you can bring him home.

Since "you never get a second chance to make a good first impression," how you stage the initial introduction is important. You can help dogs start off on the right paw together if you introduce them on neutral territory, perhaps in a park, instead of at home, so that your resident dog first regards the stranger as a possible friend rather than as a threat to his territory and dominance. Have someone else bring the new dog, so that your dog has no immediate reason to feel jealous, either. Let the dogs get to know each other, and play together, before you take them home.

Once together, adjustment is mostly a matter of coping with feelings of jealousy and sibling rivalry. "I believe dogs are capable of jealousy and resentment," says Dr. Lockwood, and these feelings can lead to undesirable behavior. Lots of reassurance and attention are in order. Make a fuss over your resident dog and downplay the presence of the newcomer. Dr. Lockwood suggests using the new dog as a cue for doing nice things with the resident dog; when you pat the new dog, pat the resident. When you take the new dog for a walk, take the old-timer. When you give the new dog a toy, give one to the resident. This trains the resident to have positive feelings about the new dog, since when she sees the new dog being patted or walked, she knows she will also enjoy these pleasures. "If the quality of life for the resident dog improves as a result of the arrival of the newcomer, if now there are more pats, more walks, more toys, the resident, one hopes, comes to feel 'Hey, maybe this isn't so bad,' " says Dr. Lockwood.

If the resident dog displays any inappropriate aggressive behavior towards the newcomer, the behavior should be quickly and firmly corrected, since the dogs must learn what is acceptable and what isn't. But do not force the animals to be together if they do not get along. "Their way of resolving differences and establishing a relationship may be by avoiding each other," points out Dr. Lockwood. "They may rotate their activities, sleeping, eating, and playing at different times."

Extra supervision is called for if the new dog is much smaller than the resident dog. A large dog can easily injure a small one in play or overtire her. But, on the whole, dogs will work things out on their own, and, given a carefully chosen pair that has been properly introduced, probably become friends.

With cats, many of the same principles apply. Cats are very territorial and will resent the presence of an intruder, so the trick to cat introductions is to give them the opportunity to become familiar with each other and each other's scents without giving them a chance to slug it out. Dr. Lockwood suggests having a neutral third party bring the new cat into the house in a cage. Put the cage in a room where the resident cat can come up to it and smell the newcomer and leave the new cat in the cage for about an hour.

After all the cats have had a good sniff, let the newcomer out. Expect a certain amount of chasing, hissing, spitting, and growling -- it's natural. But there's not much you can do to help the adjustment process, except referee and step in if it looks as though any cat could get hurt. One way to stop a fight is to throw a blanket on the combatants or spray them with water. Unless you are certain that the cats will not fight, put them in separate quarters when you are away from home.

It may take six to eight weeks or longer for cats to settle down. The same rules apply as for dogs: try not to give the resident cats cause to be jealous and don't force the animals to be together if they do not get along. Cats, like dogs, will rotate their schedules to accommodate the presence of another cat if they're not particularly fond of each other. Don't be disappointed if they never seem close. It may be necessary to provide separate litter boxes, separate food bowls, and separate toys and beds to maintain a harmonious household, and give the cats separate individual time with you, too.

Inter-species introductions follow the same basic rules. For a successful match, choose a younger and smaller animal of the opposite sex. Usually, supervision is very important, as a resident dog can easily hurt a new kitten or resident cats, frightened by a playful puppy, can scratch the pup's nose or eyes. It's also likely that a cat, particularly a kitten, will trigger the "chase response" in a dog his instinct to chase and catch an animal running away from him. It's safer to get a slightly older kitten, perhaps six or seven months, if there is already a resident dog, since he will be better able to defend and protect itself.

Companion animals bring so much happiness and pleasure into our lives, it's not surprising that many people choose to have more than one. If it is possible, a careful choice of animals and proper introductions will help minimize problems and maximize chances for a harmonious household. While the adjustment period may be hectic, once the fur settles, most multi-pet families live in loving accord, with every member the happier for having friends, playmates, and companions.

Copyright © 2001 The Humane Society of the United States All rights reserved.