“Stud tail”

The name may sound somewhat sexy, but the condition itself certainly isn’t. Cats possess a preen gland, a sebaceous gland at the base of the tail. If the gland becomes hyperactive, it can lead to blackheads, waxy debris, and painful boils.

It is technically called tail gland hyperplasia, and the common name, “stud tail,” stems from it being most common among sexually active male cats, even though it does occur among neutered males and among females.