Why is there a bald, pus-filled patch behind my cat’s ear?

If a cat has a bald patch behind the ear with pus, it may be skin inflammation caused by fungal or bacterial infection, or it may be due to a parasite infection. It is recommended to take the cat to a pet hospital for a skin scraping examination to find the specific cause and apply effective treatment. If a vet visit is inconvenient for now, apply a pet-specific broad-spectrum antiseptic spray, then observe whether the cat’s symptoms improve.

If symptoms do not improve or worsen, take the cat to a pet hospital as soon as possible.