By Jennifer Copley (Last Updated 21 November 2011)
There are many causes of skin lumps and bumps in pets, as well as things that can be mistaken for lumps such as ticks or tangled fur mats. If you do discover a lump, it doesn’t automatically mean that your pet has cancer. Many lumps are caused by cysts, allergic reactions, benign tumours, and infections.
Skin Lumps in Cats and Dogs Caused by Abscess
If a pet has recently been in a fight and suffered a puncture wound, it may become abscessed. Primary symptoms include:
- A swelling that feels warm or hot
- Pain at the site of the lump
Additional symptoms may include lethargy, loss of appetite, and fever.
The abscess may burst on its own, allowing the pus to drain, in which case you just need to wash the area with warm, salty water and keep an eye on it to make sure it’s not infecting. If the abscess is large, it fails to drain on its own, or your pet has additional symptoms, consult a veterinarian.
Skin Bumps in Dogs and Cats Due to Allergies
Cats and dogs can develop inflammatory swellings, red skin, hair loss, and small crusty bumps in reaction to:
- Flea allergies
- Food allergies
- Injected, inhaled, or topically applied drugs
- Bites or stings from bees, wasps, mosquitos, chiggers, spiders, or ticks
- Certain plants (particularly those in the Wandering Jew family)
- Chemicals (i.e., cleaning products)
If a food or flea allergy is suspected, try a hypoallergenic diet and use natural, non-toxic flea control. If the problem is allergic dermatitis, a veterinarian may prescribe antihistamines or corticosteroids.
Skin Lumps Caused by Cancer in Cats and Dogs
Skin cancer is most often found on the ears, nose, lips, or eyelids where skin is more exposed to radiation due to lack of fur. At the precancerous stage, the afflicted skin usually appears sunburned. Later, it may become scaly, with small crusty lumps. Additional signs of cancer include:
- Bleeding at the site
- A spreading or ulcerating mole
- An open sore that doesn’t heal
Cats and dogs with white fur and pink skin are most susceptible to skin cancer, so they should be kept inside during the hottest hours of sunny days. Skin cancer is treated by surgical removal of the cancerous tissue.
Lumps may also appear on the chests of cats and dogs. In unspayed females, such breast lumps are often malignant tumours. Pets that are spayed very young have a much lower risk of developing breast cancer (spaying before first heat provides the most protection).
Breast cancer spreads rapidly, so lumps should be investigated as soon as they’re noticed. Breast cancer treatments include chemotherapy and surgery. If treated early, prognosis is often good.
Not all tumours are cancerous – many are benign, so owners shouldn’t automatically assume the worst should they discover one. Lipomas (benign fatty tumours) are very common.
Acne in Dogs and Cats
Cats most often develop acne on their chins and it can become a lifelong condition. Afflicted dogs usually have acne on their lips and chins. The condition is more common in young dogs (5-8 months of age), often resolving after 12 months of age.
Acne may start as blackheads but swell into pustules. In some cases, the entire affected area swells due to infection. Mild cases can be treated with topical solutions, whereas severe cases may require antibiotics or steroids.
Other Causes of Skin Lumps, Bumps, and Swellings in Cats and Dogs
Skin lumps, bumps, and swellings may be caused by a number of other problems, including:
- Acral Lick Dermatitis – Caused by excessive grooming due to boredom or stress
- Calluses – Thickened, hairless spots that usually occur on pressure points such as elbows, back legs, and feet
- Cuterebra – Fly larvae that create lumps under the skin, often on the abdomen, neck, or chin
- Cysts – Lumps that are usually harmless and go away on their own unless they burst or become inflamed
- Dracunculiasis– An infection caused by the parasitic Guinea worm
- Feline/Canine Leprosy – A bacterial infection that may be treated with surgery and medication
- Foreign Bodies – Embedded items such as thorns or gun pellets, which can cause infections
- Granulomas – Firm lumps caused by reactions to foreign material, infection, or other irritants
- Hematoma – A localized pool of blood caused by trauma, often occurring on the ear, that usually heals on its own
- Hookworms – Intestinal parasites that can burrow in through the feet or belly, causing lumps
- Kerion – A lump caused by a complication of ringworm infection, with hair loss over the spot
- Micro-organisms – Bacterial, viral, and fungal infections
- Pythiosis – A serious infection caused by an aquatic mould
- Skin Tags (Cutaneous Papilloma) – Harmless growths that usually look like warts or small pieces of hanging skin
- Supracaudal Gland Hyperplasia (“Stud Tail”) – A common problem in unneutered males that causes swelling at the base of the tail, fur loss, oil, crustiness, and hyperpigmentation; treatment may involve neutering, cleansing the area, and antibiotics
- Warts – Light-coloured growths that usually appear around the mouth, eyelids, and tongue
- Xanthoma – A lipid metabolism abnormality that can cause yellowish lumps or skin lesions that is triggered by diabetes or a hereditary condition
Consult a Veterinarian
Although there are a number of benign or relatively minor problems that can cause skin lumps, a trip to the veterinarian is necessary to rule out serious illnesses, particularly if the lump is bleeding or growing rapidly, or the cat or dog has additional symptoms such as:
- Loss of appetite
- Increased appetite
- Weight loss
- Dull coat
This article is not intended as a substitute for veterinary care and consultation. Medical concerns should be referred to a qualified veterinarian.
- Bower, J., & Bower, C. (1998). The Cat Owner’s Problem Solver. Pleasantville, NY: Reader’s digest Association, Inc./Andromeda Oxford Limited
- Carlson, D. & Giffin, J.M. (2008). “Skin Lumps or Bumps in Cats.” Pets.WebMD.com.
- Marsalla, R. (2010). ” Contact Dermatitis in Cats,” “Contact Dermatitis in Dogs,” “Acne in Dogs” and “Acne in Cats.” PetPlace.com.
- Nash, H. (2010). “Causes of Solid-Appearing Lumps and Bumps on the Skin in Cats” and “Causes of Solid-Appearing Lumps & Bumps on the Skin in Dogs.” PetEducation.com.
- Pets.WebMD.com. (2007). “Skin Lumps or Bumps in Dogs.”
- Randolph, J.W., (2009). “Sebaceous Cysts in Dogs And Cats.” MyPetsDoctor.com.
- Thompson, M. (2010). “Skin Growth, Lump, Swelling or Mass in Cats.” PetPlace.com.