Help! My Cats No Longer Get Along! (Vet Answered)
This question has been answered by a vet
Veterinarian & Animal Behaviorist
With nearly two decades in veterinary medicine, Dr. Paola brings hands-on experience across multiple species. A graduate of the University of Guadalajara, she specializes in preventive care, animal welfare, and positive reinforcement training.
The Question
“Dear Dr. Paola,
Our cats have been separated for two-and-a-half years. Mari became aggressive when Katia came back from having her teeth cleaned. They now will eat together on either side of a baby gate. Mari is on medication for anxiety, and we use Feliway diffusers. We would like to reunite the cats, but we are worried about Mari’s tendency to be territorial. They are also both attached to me, and I am afraid that Mari will attack Katia if I am holding her. “ – Eileen
Quick Info about Mari and Katia
Hi Eileen,
It’s wonderful that you’ve been so patient and dedicated to helping Mari and Katia feel more comfortable around each other. The fact that they can now eat calmly on either side of a baby gate is a huge step it means they can share a space positively, even if there’s still a barrier. Given Mari’s territorial nature and her strong attachment to you, a careful and gradual approach will be key to making their reunion as smooth as possible.
Since Mari’s aggression was triggered by a change in Katia’s scent after the dental procedure, continuing scent swapping can help maintain familiarity. Rubbing a soft cloth on Katia and placing it in Mari’s resting areas (and vice versa) can further reinforce positive associations. You might also try short, supervised interactions while engaging them in a shared, enjoyable activity, such as playtime with a wand toy or positive reinforcement training. The goal is to keep them focused on something positive while gradually normalizing each other’s presence.
Your concern about Mari’s reaction when you’re holding Katia is valid. Cats can become possessive over their favorite human, and being physically elevated can make Katia more vulnerable. Instead of holding her during early interactions, try being present in a neutral, open space where both cats can move freely. It is very important to be observant of their body language. If you notice tension or even precursors of aggression, calmly redirect their focus with toys or a gentle distraction rather than intervening physically, which could escalate stress. Since Mari is already on medication for anxiety, discussing the transition with your vet may be helpful to ensure her current treatment is optimized for this process. You’re making thoughtful choices for their well-being, and with patience, they may be able to share space again—even if they never become best friends, cats can learn to tolerate each other, and coexisting peacefully is a realistic and worthwhile goal as long as each has their own territory.
Good luck,
Dr. Paola