Vet Advice: 9 Surprising Reasons Your Cat’s Lip Is Swollen

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The tissues around a cat’s mouth are exquisitely sensitive and contain complex structures to help your kitty navigate his world. There are multiple kinds of hair, glands, and skin not to mention the teeth and tongue. It’s not always easy to see an abnormality inside the mouth but you’ll usually notice right away when your cat’s lip is swollen. 

The most common cause of lip inflammation in cats is eosinophilic granuloma related to allergies. However, there are many other problems that can show up in the area. Parasites, auto-immune disease, dental problems, and toxins can also cause a cat to have a swollen lip. 

Symptoms Associated with Swollen Lip in Cats

As soon as you notice something abnormal around your cat’s lip area and/or mouth try to investigate further. You’ll often find more than just lip inflammation. Check for:

  • Swelling of the edge of the lip 
  • Ulcer or scab on lip
  • Red gums 
  • Noticeable mass/growth
  • Hair loss around the mouth
  • Scabs or sores on face/head
  • Itchy on the entire body
  • Big chin
  • Redness of lips
  • Bleeding or oozing of fluid/pus
  • Bad smell from mouth
  • Gums red at the edge next to the teeth
  • Itchy face/mouth
  • Shaking the head a lot
  • Decreased eating
  • Changes in drinking habits
  • Dropping food/chewing strangely
  • Rubbing face with paws or on objects
  • Gagging
  • Exaggerated swallowing
  • Drooling
  • Enlarged lymph nodes between the lower jaw & neck

Causes of Feline Lip Swelling

Eosinophilic Granuloma Complex (EGC)

As I mentioned above, one of the most common causes of lip swelling in cats is an eosinophilic granuloma, also known as EGC, feline indolent ulcer or “rodent ulcer.” Puffy lip margins are typical in EGC but cats can also develop skin ulcers and inflammation on their feet, legs and bellies. 

cat's lip is swollen
Typical reddish swelling on a cat’s lip

Eosinophils are a type of white blood cell activated in allergic responses. These cells flock to the affected area and cause swelling as they try to fight off a perceived threat. The most common causes of an allergic reaction include:

  • Food
  • Contact (especially from a food dish)
  • Flea bite allergy
  • Mosquito bite hypersensitivity
  • Atopy (pollen)

While veterinarians do have ways to test for some allergies, sometimes it’s a matter of removing exposure to various things and waiting to see if the allergic reaction and lip swelling improve. 

An easy thing you can try right away is changing the type of food dish you use for your cat. Ceramic or glass seems to cause fewer problems than plastic and stainless steel. No matter what kind of food dish you use, start washing it with hot, soapy water between EVERY meal. 

Demodex Mites

Demodex is a type of parasitic mite that lives in many animal species’ skin and hair follicles. Cats have two known types-Demodex cati and Demodex gatoi along with one unnamed type. 

Demodex mites don’t always cause problems, in fact, many normal cats may harbor a few D. cati mites. D. gatoi mites are less common and unlike D. cati, they can be spread between cats. 

It’s not unusual for cats to have hair loss, small scabs and even mild swelling as a result of Demodicosis. Lesions may appear on the body, head, ears and even the lips of an infected cat. 

Pemphigus 

Pemphigus is an immune-mediated disease in which the connections between skin cells are destroyed. The symptoms of pemphigus include pustules, scabs and swelling that can affect the skin on the lips as well as other parts of the body. 

A skin biopsy is the best way to diagnose pemphigus in cats. In most cases, there is no identifiable cause (1). Different forms of pemphigus respond variably to medical treatment. 

Oral Tumors

Various tumors can affect the tissues of a cat’s oral cavity and cause the appearance of lip swelling. Tumors may be benign or cancerous and it’s hard to tell the difference without a biopsy in many cases. 

The three most common oral tumors in cats are squamous cell carcinoma, malignant melanoma and fibrosarcoma (2). All three carry a poor long-term prognosis. 

Skin Tumor

Cancers of the skin occasionally start around a cat’s mouth area. Mast cell tumors and cutaneous lymphoma can both cause a lesion that might look similar to more benign causes. Diagnosis is best made by biopsy. 

Dental Disease

Teeth problems are extremely common and increase as cats get older. As a veterinarian, I see the gamut in oral problems from just a little gingivitis to stomatitis and tooth resorption. Sometimes the inflammation is so severe it can cause lip swelling, too. 

The only way to fully diagnose dental problems is with a thorough oral examination and intraoral radiographs. Anesthesia is required to accomplish this, but your cat will thank you in the end. Don’t fear anesthesia–it’s come a long way in the last 20 years and many safe options are available. 

Discuss your concerns and fears with your vet so you can feel confident about helping your cat with dental disease. 

intraoral radiographs for dental disease and oral tumors
Oral x-rays help diagnose dental disease and tumors

Infection 

Skin infections sometimes affect the tissue of the face and lips. Bacterial infections and abscesses from things like Pasteurella and Staphylococcus are more common in cats who spend time outdoors. Fighting with other cats and other kinds of trauma are often the culprit.

Fungal infections like ringworm cause hair loss, red skin, and sometimes crusting. I’ve seen cats with crusty ears, noses, and lips from ringworm infections. A simple skin culture will help diagnose ringworm. 

Chin Acne

Should we call it “chacne?” In any case, feline chin acne is just what it sounds like–follicles on the chin area become plugged and inflamed. It usually looks like blackheads, dirty fur, reddish skin and sometimes a puffy lower lip. 

Chin acne is often related to allergies and some of the same treatment methods are used. 

Chewing Pothos can cause a cat's lips to swell
Pothos is a common houseplant

Toxins 

Pothos Scindapsus and Epipremnum are tropical house plants that belong to the Araceae family. If chewed or ingested by a cat, Pothos can cause significant swelling of the cat’s mouth, lips and gastrointestinal tract.

It’s a good idea to avoid having Pothos and cats in the same home. If you want to have both, make sure the plant is in an area the cat doesn’t have access to. 

Diagnosis 

Before you make a trip with your cat to the vet clinic, look around the house and see if you can collect more clues for your vet. Has your cat been eating and drinking normally? Any changes in litter box habits? Have you changed her food, toys or bedding? Have you ever seen these symptoms before?

Your veterinarian might want to do some testing before treating your cat’s lip problem. These tests might include:

  • Skin Scrape
  • Fungal culture
  • Bacterial culture
  • Allergy testing
  • Biopsy
  • Radiographs
  • Blood Tests
  • Medication Trial
  • Food Trial

Treatment

It’s important to try to identify the underlying cause when your cat’s lip is swollen, but it’s not always possible to get a definitive diagnosis. Your vet will make a recommendation for treatment based on what they find out. 

A brief summary of treatments for problems I covered above:

  • Allergy/EGC– steroids (oral or injectable), Atopica/cyclosporine,  flea/mosquito control, food trial with hypoallergenic food like Royal Canin HP. 
  • Demodex– treatment with spot-on like Bravecto, or injectable ivermectin.
  • Chin Acne-similar to allergy treatment plus cleaning skin, benzoyl peroxide to flush follicles.
  • Dental Infection– clean all teeth, radiograph and extract abscessed teeth, antibiotics.
  • Oral Tumor– radiographs, biopsy, surgical removal, radiation treatment.

Cost of Veterinary Care for Swollen Cat Lips

As for cost, it really depends on whether there are other symptoms besides an inflamed lip. You may end up spending between $100 and $300 for a simple case with EGC. It could cost up to several thousand for to diagnose and treat recurring skin disease, dental disease or tumors. 

Summary

When your cat’s lip is swollen don’t just assume it’s caused by an allergy/eosinophilic granuloma complex (EGC). There are many other causes that can look very similar to EGC. 

Let your vet take a look and recommend the next step. The proper diagnosis and treatment will save you money and time, not to mention getting your cat back to normal quicker!

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References

  1. Scott DW, Miller WH, Griffin CE.: Immune-mediated disorders. Muller and Kirk’s Small Animal Dermatology, 6th ed. Philadelphia, WB Saunders 2001.

2. Stepaniuk KS: Identifying and Treating Oral Tumors in Practice. Chicago Vet Conference 2019.

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