Lumps and Bumps in Dogs and Cats

You’re cuddled on the couch, petting your furry friend, and it happens: you feel a lump. Suddenly, your mind is racing with questions. Is it new? Is it growing? And worst of all, is it cancer? Maybe, but maybe not. There are a whole host of conditions that can cause lumps and bumps to appear on aging pets. Many of these conditions appear similar, and it can be difficult to tell them apart by appearance alone. Fortunately, a veterinary exam and a few simple tests can usually diagnose the problem. Your veterinarian may choose to perform a fine needle aspirate, which involves using a needle to remove a few cells from the lump and examining them under a microscope, or a biopsy, which involves either removing a small piece of the lump or the entire mass for further evaluation. Listed below are some of the most commonly diagnosed lumps and bumps:

Non-cancerous lumps in pets:

These are often caused by infections or allergic reactions and can be cleared with medication or other treatments.

–Sebaceous cysts: smooth, round  bumps (similar to a pimple) that are caused by a blocked oil gland in the skin and can be painful if they get large.

–Warts (papillomas): small, cauliflower-like growths around the mouth caused by a viral infection, usually found in young dogs.

–Abscess: a collection of pus under the skin caused by an infection following a bite or injury.

Tumors: A tumor is simply an abnormal growth of cells, and they can be benign or malignant (cancerous). Some malignant tumors can spread throughout the body and endanger the life of your pet. They are often treated with surgery, radiation, and/or chemotherapy. Benign tumors typically do not spread and surgical removal may not be necessary unless they are in a location that bothers your pet.

Common benign tumors in pets:

–Lipomas: soft, movable tumors formed from fat tissue under the skin. They are very common in older dogs, particularly in overweight, large breed females and are usually no surgically removed unless they are causing a problem.

–Skin tags and fibromas: hairless lumps that appear firm and rubbery. They may be on a small “stalk” off the skin.

–Sebaceous gland hyperplasia (adenoma): small, pink, cauliflower-like (bumpy) mass on the skin surface usually found in older dogs, especially Cocker Spaniels.

–Histiocytoma: a raised, pink, hairless mass typically found in dogs less than 2 years old that usually goes away on its own.  Also known as the “button” tumor.

Common malignant tumors in pets:

–Malignant melanoma: a dark colored, often ulcerated tumor commonly found around the lips or nail bed.

–Mast cell tumors: varied appearance, often small and soft. These tumors may remain small for long periods of time before suddenly growing rapidly.

–Lymphoma: raised plaques or red patches on the skin, often accompanied by flaky skin or hair loss.

–Squamous cell carcinoma: white plaques on the skin that may bleed or be red and ulcerated.  Usually found on areas with minimal hair and lightly pigmented.

–Anal sac apocrine gland tumors: firm masses located in the anal glands on the buttocks.

Of course, this is not an extensive list, and many other diseases and cancers can cause lumps on the skin of aging pets. The best thing to do when you notice a new lump is to schedule a visit with your veterinarian. If the lump appears to be growing rapidly, is red, swollen, or painful, or is filled with pus, schedule that appointment even sooner. Whether the lump is simply a cosmetic nuisance or a dangerous disease, your veterinarian can advise you on the best course of action.

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