Visiting Vet: Intercat aggression

What can you do if Nobody and Farfel just don’t get along?

A young Michelle Jasny holding a little white kitten. — Courtesy Michelle Gerhard Jasny

I was 13, palling around with my friends downtown, when we came across a man dangling a paper bag off a bridge over the river. When we heard a faint mew, we insisted he give us the bag. Inside — a tiny white kitten. Riding the bus home, the kitten sat quietly in my lap. No one discussed who was going to take it, unannounced, to our parents. But as we got off the bus, my friends scattered, and I was left holding the bag.

We named her Nobody. Our other cat, Farfel, hated her the moment she arrived. As she grew, so did the cat-to-cat altercations, to the point we decided to keep them separated. We didn’t know much about feline behavior. We just didn’t want fighting. Since our house was on a quiet, dead-end road, both cats went outside. When Farfel wanted to come in, the person at the door would shout “Is Nobody home?” Then we would locate Nobody, and put each cat in a different area to prevent the fur from flying.

Intercat aggression. Mild spats between household cats are normal. One survey found that 80 percent hiss, 85 percent swat, and 70 percent fight occasionally. Most people can tolerate a kitty hissy fit now and then, but when fighting becomes more serious, it disturbs the peace of the house. Intercat aggression is the most common reason, after inappropriate urination and defecation, that cats are brought to veterinary behavior specialists. So what can you do if Nobody and Farfel just don’t get along? 

It’s not a simple question with a simple answer. We usually start with a thorough physical exam of both combatants to rule out medical reasons. Maybe Farfel has arthritis, and pain is making her grumpy. Maybe Nobody has hyperthyroidism, and the metabolic imbalance makes her hyper. 

Once medical issues are eliminated, a detailed history is necessary to try to pinpoint behavioral causes. Aggression can result from territoriality, fear, or redirected aggression. Is Farfel being territorial, protecting her turf? Is Nobody so fearful and timid that she runs away, triggering Farfel to chase her? Do we need to help Farfel chill and share her space? Or do we need to give Nobody more confidence not to run? We must determine which animal is causing the problem, or if it is both.

In our case, Farfel had lived alone in the house for years, and considered it her turf. Adult male cats, even neutered ones, are more likely to exhibit territorial aggression than females, but any gender and age cat may engage in this behavior. Hissing, growling, stalking, chasing. Farfel is simply saying, “This is my house. You get out!” Nobody, however, was too timid. When she would start running and hiding, this provoked Farfel to go after her. It’s tempting to think of them as “bully” and “victim,” but this is not really fair. Both cats are just reacting on essentially normal instincts to a living situation to which they did not consent. Redirected aggression is when the cat who is upset lashes out at a different target. Like “kick the dog” syndrome in people. Maybe Farfel is upset when she sees stray cats outside through the window, and she lashes out at Nobody instead. Redirected aggression can also be aimed at you, the owner, so be cautious. If Farfel is riled up, she may bite you instead of Nobody if you try to intervene. 

Treatment for intercat aggression requires time and patience. Start with environmental adjustments by creating a “house of plenty.” When cats fight, it may be about access to valuable resources. Provide an overabundance of cozy sleeping places, litter boxes, water bowls, climbing trees with hiding spaces, and toys. Feed cats separately. Evaluate the home for “choke points” — places where Nobody and Farfel find themselves forced to interact, such as halls and narrow doorways. Alter traffic flow so each cat can access everything they need without having to pass the other. Use Feliway MultiCat — a calming synthetic pheromone — in diffusers throughout the house. If the aggressor cat will tolerate a collar and bell, that may help the timid cat avoid confrontations.

In cases of more intense fighting, cats should be separated, and a behavioral modification program of desensitization and counterconditioning instituted. Gradually acclimate each cat to the other cat’s scent. Rub each cat with a towel, add a spritz of Feliway, then let Nobody smell Farfel’s scent and vice versa. Then allow them to see each other through a barrier. When our Nobody and Farfel saw one another through the glass door, Farfel would still hiss and bristle. Had we consulted a behavior specialist, they would have told us to make a double barrier, with a neutral zone in the middle. Think North and South Korea. Providing special, delicious treats while the cats see one another from a distance will help build positive associations. Once the cats tolerate visual contact, some suggest putting the confident cat in an enclosure and letting the fearful cat roam around briefly, while both cats get positive reinforcement. This is fine unless either cat gets overly aroused. The goal is to never provoke aggressive or fearful behavior as the cats slowly learn to get along. If things go well, the cats can spend more time near one another, and get closer and closer together.

Then there are drugs. The problem with drugs is owners want to give them, and forget about behavioral modifications. Medication alone is often not enough, but, yes, various antidepressant and/or anti-anxiety medications can be tried. Sometimes the aggressor needs medication, sometimes the victim, sometimes both. Medications may take one to two months to reach full effect, and may require trial and error to find the most effective ones for any given cat. 

The bottom line — it takes time and effort to resolve intercat conflict. Sometimes nothing works, and one cat needs to be rehomed. Nobody and Farfel eventually arrived at a manageable détente, but our family still remembers the days of “Is Nobody home? Yes, Nobody’s home!”