Being scratched by a cat is a common phenomenon, mostly due to capillary damage, but if the patient has other concomitant symptoms such as itching, fever, ulceration, suppuration, etc., it may be allergies, infections, contact dermatitis, cat scratch disease, etc.：
Capillary damage:
Usually, there are more capillaries under the skin of the human body. After being scratched by a cat, the capillaries rupture, and the patient may experience local bulging.；
Allergies:
If the patient has bulging bags after being scratched by a cat and is accompanied by symptoms of itching, it is considered an allergy.；
Infection:
Since the cat's paw is not a clean object, when the human body is scratched by a cat and there is a local infection, bulging, pain, increased skin temperature, and other phenomena can occur.；
Contact dermatitis:
Contact dermatitis refers to single or multiple exposures of the skin and mucous membranes to the animal, chemical, and plant substances, causing local acute or chronic inflammatory reactions on the skin. Cat scratching is an animal factor, and patients can experience bulging.；
Cat scratch disease:
When the human body is scratched or bitten by a cat, the whole body of Saiba invades the human body, and the patient may have one to several erythematous papules locally, and a few papules can turn into blisters or pustules. Most patients have symptoms such as fever, fatigue, and anorexia.
When the patient is scratched by a cat and the bulging bag appears, the wound needs to be disinfected in time and treated as soon as possible. It is up to the doctor to judge the treatment method according to the specific circumstances, and at the same time to determine whether rabies vaccine, tetanus vaccine, etc. need to be injected.