Swellings in cats are a common finding in cats, a swollen chin may have a number of causes.
The most common cause is condition known as feline acne. Blackheads and swelling on the chin and lips are the most obvious symptoms, with inflammation and swelling also common. While not serious to your cat, it can cause some discomfort. There are many possible causes including the use of plastic water bowls, poor grooming, overactive sebaceous glands and hormonal imbalances.
Feline acne is straightforward, switch to glass or ceramic food bowls and wash frequently. Clean the chin area with an antibacterial soap or iodine (Betadine), which should be diluted to the colour of weak tea. Severe cases will require cleansing the skin with an ointment or gel containing benzoyl peroxide (such as OxyDex) or chlorhexidine. Topical steroids may necessary reduce inflammation and oral antibiotics if the area has become infected.
Insect bite or sting
Ant bites, spider bites, and bee stings are the most common bites and stings in cats causing localised swelling, itching and pain.
In most cases, this will resolve itself within a few hours, but you may choose to give your cat some Benadryl (diphenhydramine hydrochloride). This can help to reduce inflammation and itching.
A localised collection of pus caused by a cat bite, abscesses can occur on any part of the body, but the head, limbs, and back, near the base of the tail, are the most common areas.
An abscess will form a firm, painful lump which feels hot to the touch. Other symptoms may include fever and loss of appetite. Eventually, this will open up, with a foul-smelling liquid discharge coming from the wound.
A veterinarian will need to lance the abscess, flush it with antiseptics and administer antibiotics.
The most common oral cancer to develop in cats is squamous cell carcinoma, this cancer is particularly invasive, often spreading to surrounding bones and tissues. Other symptoms of oral cancer include a lump in the mouth, loose teeth, bad breath, difficulty eating and drooling.
Oral cancer can be hard to treat due to the speed in which it invades surrounding tissue, an early diagnosis offers the best prospect. Surgical removal if the cancer is located in the lower front jaw, chemotherapy and/or radiotherapy are also treatment options.
Similar to an abscess, a dental abscess occurs when bacteria invade the gums or tooth roots. Common symptoms are a reluctance to eat, swelling, loose teeth, and fever.
Removal of the affected tooth, cleaning the abscess and antibiotics.
Allergic reaction (rodent ulcer)
Almost anything can cause an allergic reaction in cats which can result in swelling on the chin and lip, with flea bites, food bowls, and food being the most common causes.
Finding and eliminating the cause and if a food allergy is a cause, switching to a different type of food should resolve the issue.
Eosinophilic granuloma complex
A condition characterised by the presence of skin lesions which can occur on many parts of the body including the face and chin. There is a high suspicion that allergies to flea bites are the cause.
Avoidance of allergens, if known. This may include switching to a hypoallergenic diet, strict flea control and steroids to reduce inflammation. Severe cases will require immunosuppressive drugs.