5 Reasons Why Your Cat's Hair Stands Up
Last updated: October 22, 2026. Key takeaways A cat’s fur stands up through a reflex called piloerection. According to Preventive Vet, it is usually triggered by cold, fright or arousal, including aggression. Raised fur is a signal, not a diagnosis. Read the ears, tail, eyes and posture along with the fur. A puffed-up cat usually needs space. Do not pet, pick up or corner it. Rippling skin along the back, sudden biting at the back or tail area or unusual behavior with no trigger can point to a medical problem, so call your vet. You turn around and your cat looks twice its normal size, tail like a bottle brush. It is dramatic and a little funny, but your cat is telling you something. Here is what vets and behavior experts say raised fur can mean and how to respond. Disclosure: As an Amazon Associate I earn from qualifying purchases. Some links on this page are affiliate links, at no extra cost to you. What is piloerection? Preventive Vet explains that piloerection, often called “raised ...