One cat is great. Two can be even better, if they get along. The problem is that cats aren't naturally social animals in the same way dogs are. In nature, they live alone or in family groups by choice, not necessity. Forcing cohabitation with a strange cat can work or can be disastrous.
If you're thinking of adding a second (or third, or fourth) cat, or already have several and need to improve cohabitation, this guide will help.
Before adopting another cat
Honest questions to ask yourself:
Does your current cat seem to want company? Some cats love other cats. Others tolerate. Others absolutely detest. If your cat is territorial, reacts badly to cats it sees through the window, or has never lived with other felines, adaptation will be more difficult.
Do you have space? Not just square meters, but multipliable resources: litter boxes, feeding points, hiding places, high places. Cats need to be able to avoid each other when they want.
Do you have time and patience? Well-done introduction takes weeks, sometimes months. Are you willing to invest that time?
What if it doesn't work? What's plan B? Returning the new cat isn't ideal. Keeping cats that hate each other separated forever isn't either.
Choosing the new cat
Compatibility isn't guaranteed, but some combinations have better chances of success:
Kittens are usually more accepted by adults. Less threatening, more flexible. But a hyperactive kitten can stress a calm adult cat.
Cats with similar energy get along better. A playful young cat with an old one that just wants peace is a recipe for frustration on both sides.
Sex matters less than personality, especially if all are neutered. But some studies suggest female-female combinations have more conflict, perhaps because females are more territorial.
If possible, choose a cat that has already demonstrated living well with others. Shelters and rescuers can inform about this.
The introduction: step by step
The temptation is to put the two together and "let them work it out". Don't do that. First impressions matter, and a bad introduction can create animosity that lasts years.
The new cat stays in a separate room with everything it needs: food, water, litter box, scratching post, hiding place. Door closed. The cats don't see each other.
Duration: at least 3-7 days, more if necessary.
Goal: the new cat gets used to the environment. The resident notices there's another cat, but doesn't feel its territory invaded.
Swap items between cats: blankets, toys, scratching posts. Let each one smell the other in its own space.
Rub a cloth on one cat's cheek and let the other smell it. Facial glands produce "friendly" pheromones.
Observe reactions: curiosity is good, aggression to the smell already indicates problems.
Place each cat's food bowls on opposite sides of the closed door. They eat knowing the other is there.
Start with distance from door that doesn't cause stress. Gradually bring closer over days.
Goal: associate the other's presence with something positive (food).
Replace the door with a barrier that allows seeing but not passing: baby gate, slightly open door with lock, screen.
Short sessions initially. Offer treats or play during visual contact to keep it positive.
If there's growling, hissing or agitation, increase distance or go back to previous phase.
Let both in the same space, but supervised. Keep sessions short. Have thick blanket or water spray ready to separate if necessary (but only in emergency, not as punishment).
Gradually increase duration as things flow well.
Occasional growling and hissing are normal at first. Aggressive pursuit or fights are not.
When supervised meetings are consistently calm, you can start leaving them together when you're not watching. Monitor for a few more weeks.
Resources: the golden rule
The basic formula: number of cats + 1 for essential resources.
2 cats = 3 boxes
In different locations
Separated to avoid competition
Can be same room, sufficient distance
Multiple around the house
Away from food
Several, so each has options
Shelves, cat trees
Each cat needs refuge
Where it can be alone
Multiple around the house
Avoids territorial dispute
Cats that need to compete for resources get stressed, even if the competition is subtle and you don't notice.
Signs of good cohabitation
This is good:
Sleeping near or together. Grooming each other (allogrooming). Playing without aggression. Passing each other without tension. Sharing space without problems. Tails up when they meet.
Signs of problems
More subtle signs that many people don't notice:
A cat that's always hidden, avoiding common areas. One that stops using the litter box in a certain location. Fixed and intimidating "stares". One cat blocking passages while the other detours. Body tension (fur, ears) when in the same environment.
Cats can be in conflict without ever fighting physically. Silent tension is still stress.
If cohabitation isn't good
First, ensure resources are sufficient and well distributed. Many "personality conflicts" are actually resource conflicts.
Synthetic pheromone diffusers (like Feliway) can help reduce general tension.
If you identified serious tension or fights, consider restarting the introduction from scratch. Separate completely and redo the phases gradually.
Consult a behavioral veterinarian if things don't improve. Sometimes temporary medication helps break the stress cycle.
In extreme cases, cats can be incompatible. Options: keep permanently separated in different areas of the house, or rehome one to a home where it will be the only cat. It's not failure, it's recognizing that not every combination works.
How many cats is too many?
Depends on space, the cats and you. There's no magic number. But signs that you've exceeded the limit include:
- Behavioral problems appearing (urinating outside box is classic)
- Difficulty maintaining hygiene and resources for all
- Visibly stressed cats
- You can't give sufficient individual attention
- Veterinary costs becoming unsustainable
Practical rule I heard from a veterinarian: "The maximum number of cats is the one where you can still immediately notice if one of them is eating less or acting differently."
The benefits when it works
Cats that get along play together (great for energy expenditure), groom each other (reach places they wouldn't alone), keep each other company when you're not there. Seeing two cats sleeping cuddled is one of the cutest things in the world.
It's worth the effort to do it right. Just don't underestimate that effort.