Normally, a cat’s gums will not have a ring of redness. Generally, this situation may be caused by gingivitis, dental calculus, stomatitis and other diseases. You should pay attention to the cleaning of the cat’s oral cavity. You can buy pet-specific toothpaste and toothbrushes every day. Help the cat clean, or use pet oral spray to relieve the cat's symptoms. If the situation is serious, you need to take the cat to the pet hospital for examination and treatment, and tooth extraction if necessary.