Redirected Aggression in Cats: Why Your Cat Attacked Without Warning

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

It often happens in an instant. Your cat is watching a stray in the yard, and a moment later it flies at the other cat in the house or at you. The attack seems to come from nowhere. In fact, it has a name, redirected aggression, and a predictable cause.

What is redirected aggression?

A cat becomes highly aroused, by fear, frustration or excitement, by something it cannot reach. The arousal has to go somewhere, and the cat directs it at whoever or whatever is closest. It is not an attack on that person or pet but a spillover of emotion.

Common triggers

• A cat or animal seen through a window or door
• Loud noises, such as fireworks or construction. See fireworks and thunderstorms and cats.
• A vet visit or carrier trip. See carrier training a cat.
• Being startled
• Frustrated hunting, such as chattering at birds. See why do cats chatter at birds.
• Smells of other animals on you or another pet
• Interrupted fights or play
• Changes in the home

Signs of high arousal

• Dilated pupils
• Flattened or rotated ears
• Puffed tail or lashing tail. See cat tail language.
• Growling, hissing or yowling
• Stiff, tense body
• Fixed staring

What to do if it happens

1. Stay away. Do not touch or try to calm the cat. You can be seriously injured.
2. Block the trigger. Close curtains or remove the stimulus, if safe.
3. Separate cats. If another cat is the target, separate with a barrier or a towel. Never use your hands.
4. Give the cat a dark, quiet room with food, water and a litter box.
5. Let it calm down fully. Cats can stay aroused for hours.
6. Check for injuries to people and pets, and wash wounds. See a doctor for deep bites, since cat bites can become infected.

Rebuilding relationships

If one cat attacked another, the victim may now fear the aggressor, and the aggressor may associate the other cat with the arousal. Separate them for several days. Then reintroduce slowly. See how to introduce a new cat to your cat. Use treats and play to build positive associations. Watch for persistent tension. See aggression between cats.

Prevention

• Block views. Use window film, curtains or furniture to stop your cat seeing outdoor animals.
• Deter strays. Remove food sources and use humane deterrents.
• Provide outlets. Daily play, puzzle feeders and climbing. See indoor cat enrichment ideas.
• Keep routines steady.
• Use pheromone diffusers, if advised by a vet.
• Provide hiding places. See why do cats hide.
• Avoid handling a stressed cat.

When to see a vet

Contact your vet if aggression is frequent, severe or comes with other signs. Pain and illness can lower tolerance. See the emergency warning signs guide. A veterinary behaviorist can help with a plan, and sometimes medication. Use the US vet directory to find a clinic.

Why the target is often someone the cat loves

Redirected aggression can be confusing because the target is often the cat's closest companion. The attacked cat then smells different, perhaps of the outdoor cat or of the vet, or it simply reminds the aggressor of the stressful moment. The first cat may hide or growl at the other for days, and the second cat may begin to avoid the first. This is why a single incident can grow into a long feud if you do not manage it promptly.

How long to wait before reintroducing

There is no fixed timetable. A common approach is to keep the cats apart until both are eating and moving around normally, then restart with scent swapping and feeding on opposite sides of a door. If either cat hisses, stiffens or stares, go back a step. Rushing is the usual cause of repeat attacks. Mild cases may resolve in a few days, while severe ones can take weeks.

Helping the victim

The cat that was attacked needs reassurance too. Give it a safe room, quiet time and food it enjoys. Do not force contact. Watch for signs of fear, such as hiding, loss of appetite or litter box changes, and mention them to your vet if they last.

Teach everyone in the home

Make sure children, partners and visitors know that a growling, dilated-pupil cat should be left alone and that nobody should try to pick it up. A calm household response, quietly closing a door or blocking the view, protects both people and pets.

Safety

Keep children and visitors away from an aroused cat. Do not corner or pick up the cat. Teach family members to read warning signs. See how to pick up and hold a cat.