Generally, an abscess is caused by a bacterial infection. There are multiple ways your cat could become infected and develop an abscess. Some of the most common causes include: Animal bites: If you have an outdoor cat or a cat who interacts with other animals, they could develop an abscess after being bitten. Blood-borne infections: A cat that’s been exposed to blood-borne bacteria could develop an internal abscess in the liver or other organs. Tooth damage: Cats are notorious for dental problems. A damaged tooth could cause an abscess to form at the roots.