Not necessarily. Pyometra is a disease that occurs in the reproductive system. Whether it is a disease depends on the physical condition of the cat. Not every cat will have pyometra without sterilization, but sterilized cats will definitely not suffer from pyometra. Pussy. After sterilization, the cat's organs that secrete sex hormones are removed. The cat will not be in estrus or have secretions, so there is no possibility of reproductive system disease.