Cat Aggression After a Vet Visit: Why Your Cats Are Fighting

TL;DR: Post-vet aggression occurs when a returning cat smells unfamiliar, causing a companion to react with hostility; while usually a low-level behavioral issue, you should separate the cats immediately to prevent injury.

What is post-vet aggression in cats and why does it occur?

This behavior is commonly known as non-recognition aggression. When a cat returns from a veterinary clinic, they carry unfamiliar scents such as medications, cleaners, and the odors of other animals. To the cat who stayed at home, their companion no longer smells familiar, which triggers a fear-based defensive response or outright hostility.

Is post-vet aggression between my cats considered an emergency?

• The urgency level for this situation is Low, as it is a behavioral issue rather than a medical crisis.
• Separate the cats immediately to prevent physical injury and reduce stress.
• If a cat is significantly injured during a spat, the urgency level increases to a physical medical concern.

Why should I provide a photo or video to help with the triage process?

• Capturing a short video of the cats' body language helps your veterinarian or a behaviorist determine the severity of the aggression.
• Visuals help distinguish between minor hissing and dangerous physical lunging.
• Accurate triage allows professionals to provide specific advice on reintroduction techniques or potential calming supplements.