1. This may be due to swelling caused by bites of external parasites such as mosquitoes and ticks. You can shave off the hair of the cat's affected area first, so that the affected area can be exposed and easy to observe.

2. If the cat scratches the affected area, it is suggested that the owner put a elizabeth circle on the cat, and then you can observe whether the affected area is aggravated first.

3. If the affected area continues to deteriorate or worsen, or other abnormal symptoms such as ulceration appear, it is recommended to take the cat to the pet hospital for examination.

4. It may also be because of the tumor and inflammatory granuloma of the skin. Fine needle puncture can be performed to determine whether surgical resection is needed according to the examination results.

5. Third, it may be swelling caused by traumatic infection. In this case, cats usually have a history of fighting or injury, and the affected area usually has ulceration and bleeding. It is recommended to go to the pet hospital for debridement in time.