The main causes of cat mouth swelling include allergies, trauma, oral diseases, and granulomas. First of all, if the cat comes into contact with some allergens, such as food, toys, etc., it will cause allergic swelling of the lips. Secondly, if the cat accidentally pricks its lip by some sharp foreign object, the trauma will also cause inflammation and swelling. Furthermore, when cats suffer from oral diseases such as gingivitis and angular stomatitis, the disease spreads to the lower lip, causing the lips to swell. Finally, if the cat still has some itching, hair loss, redness and swelling, it is likely to be suffering from eosinophilic granuloma, which is an inflammatory disease of the skin.

　1. Allergy

If a cat accidentally eats food with allergens, comes into contact with certain allergen items, or has a drug allergy due to recent medication, it will cause lip allergies and edema. Generally, cats may also develop allergies. Symptoms such as facial redness and swelling, vomiting, and skin rash. At this time, it is necessary to find out the allergen, whether it is food, items or drugs, and then use different treatment methods according to different allergens.

　2. Trauma

If a cat’s mouth is injured, such as being scratched by sharp objects such as bones, fish bones, etc., the scratched area may become red, swollen and inflamed. In this regard, the owner can open the cat's mouth and check to see if there is any foreign body or trauma. If there is a foreign body, the foreign body needs to be pulled out first, and then some antibacterial and anti-inflammatory drugs are applied to the wound.

3. Oral diseases

If a cat suffers from oral diseases such as gingivitis and angular stomatitis, when the disease spreads to the lower lip, it may cause swelling, and the cat may also have symptoms such as bad breath, drooling, red and swollen gums, and ulcers. In this regard, the owner can check whether there is inflammation or ulceration in the cat’s mouth. If so, the cat needs to be sent to a pet hospital for treatment immediately.

　4. Granuloma

Feline granuloma is generally considered to be eosinophilic granuloma, which is a relatively common skin disease in cats. It will cause abnormal thickening, swelling, hair loss and other symptoms on the edges of the cat's lips. The general treatment method is to use anti-inflammatory drugs to control the inflammation, and at the same time, use antibacterial drugs to prevent secondary infection of the damaged area. During the treatment period, it is necessary to take medication on time and clean the cat’s mouth every day to prevent food from decaying and fermenting and aggravating the condition. In addition, it is best to give some easy-to-chew foods.