Lumpy tumors on dogs or cats are among the top 10 reasons pet owners visit the vet. Can they be a sign of cancer? Yes – but not always. It’s suggested that you visit your vet because these growths can be serious, such as with cancer. A vet can also differentiate between these and other masses, such as bony swellings and abdominal distention which are entirely different.

Types of Superficial Tumors in Dogs and Cats

The term “tumor” simply refers to superficial lumps and bumps, also known as “masses,” which are not always cancerous. Cancerous tumors in dogs and cats are called “malignant” tumors, and non-cancerous tumors are called “benign” tumors. The following are the three kinds of masses you can find on your pet:

• Puncture wounds - Puncture wounds are usually the result of bites from other animals. They form abscesses beneath the skin that eventually break open.

• Benign masses (non-cancerous) - Examples of benign masses that may or may not need to me removed are warts, skin tags, fluid-filled cysts, fatty tumors (lipomas), and histiocytomas.

• Cancerous tumors – Cancerous tumors are the scariest of all three because removing the tumor may not stop the cancer. Cancerous tumors can spread, sometimes locally and sometimes to distant parts of the body such as skin, fat, bone, muscle next to the lump.

It’s important that you visit your vet if you’re unsure the cause of your pet’s mass to assess the seriousness and whether treatment and/or removal is required.

Early signs of cancer in dogs and cats

If you suspect that your dog or cat’s tumor is a sign of cancer, the following are some early signs that may hint at giving you an effective answer:

Swollen lymph nodes
Any lumps on the pet
Non-healing wounds
Unexplained weight loss
Bad odor
Difficult breathing or urinating
Loss of appetite

No in-home diagnosis will be as effective as a veterinary inspection, so please visit your vet if you’re not confident the mass is benign.

How Common are Cancerous Skin Tags on Dogs and Cats?

Studies show that approximately one in four dogs will develop some form of cancer. In dogs over the age of 10, the statistic increases to 50%. For kitties, one in five will suffer from cancer in their lifetime. While not all cancers result in tumors or skin tags you can see with the naked eye, it is still a good idea to check your pet frequently for lumps and bumps.

What Does a Cancerous Skin Tag Look Like on a Dog or Cat?

A Google search for “cancerous skin tags on dogs images” brings up a variety of results including benign growths, cysts, ticks, and of course, some cancerous skin tags and masses.

Since the appearance of cancerous growths can vary, there is no specific set of characteristics to look for. However, these factors may help you identify a suspicious lump:

Size. Not all large masses are cancerous, but a rapidly-growing mass could be an indication of neoplasia.
Sudden appearance. If a new growth or skin tag appears suddenly on your dog, have it checked out as soon as possible.
Changes in size, color, or texture. Any of these changes to an existing skin growth could indicate cancer, especially a dark or uneven color change.
Discharge. Some cancerous growths produce a discharge, but so do many benign cysts.
Sores that won’t heal. Some cancers can look like minor abrasions. If the spot does not seem to heal, this could indicate an immune system problem or cancer.

While these signs can help you recognize a potentially cancerous mass or skin tag, it is always best to have your vet examine all suspicious growths and skin lesions. Diagnostics are the only definitive way to confirm or rule out cancer.

Photo by Joel Mills showing a cancerous mast cell tumor on a 3-year-old Boxer.

How are Cancerous Skin Tags Diagnosed?

The first step to diagnosing cancer is to schedule a veterinary exam. Provide your vet with a detailed medical history of your dog or cat, including changes in appetite, weight, energy levels, behavior, and overall health. Based on his or her findings, your vet will recommend diagnostics such as needle biopsy, radiographs (x-rays), blood tests, and ultrasound exams.

Sampling of tumors in dogs and cats either with a needle or collection of tissue from the tumor is required to differentiate a benign from a malignant tumor. A needle sample doesn’t always lead to a definitive conclusion since only a small number of cells can be collected in a needle. A needle sample does not usually require anesthesia, so it is a good place to start.

Tissue samples are collected surgically and are usually quite accurate in leading to a cancer diagnosis. Specific diagnosis of the type of cancer an animal gives veterinarians information about what treatments are most likely to help and whether the tumor is likely to come back or spread elsewhere in the body.

How are Cancerous Tumors in Dogs and Cats Treated?

Treatment varies depending on the type of cancer with which the pet is diagnosed. Some cancerous skin tags can be removed with a simple surgery, while others require chemotherapy, radiation, or additional therapies. Some veterinarians may also recommend dietary changes, medications, or supplements to help your dog or cat respond to treatment.

What is the Success Rate?

Some types of cancer can be cured completely, while others require long-term management. Response to treatment will depend on what type of cancer your pet has, how far advanced it is, and which treatments are available. As with any disease, cancer is most likely to respond to therapy if diagnosed and treated early.

Are Cancerous Skin Tags Preventable?

Unfortunately, most cancers are quite unpredictable in dogs and cats. Early spaying and neutering can help reduce the risk of mammary and testicular cancer but may increase the chances your pet will develop certain other cancers. Talk to your vet about if and when to have your pet altered.

Many dog breeds are also born with a genetic predisposition to different forms of cancer. Be sure to research your breed and investigate the breeding lines of the parents before purchasing a puppy.

The best way to protect your dog or cat from cancer is to see your veterinarian regularly to increase the chances of early detection.

Photo by Caroldermoid of a benign canine cutaneous histiocytoma.

Dr. Kent’s Two Cents on Tumors in Dogs and Cats

Not all tumors in dogs and cats are cancerous, by any means. Older dogs are especially prone to developing fatty tumors of the skin, many of which can become quite large.

Benign tumors often develop in dogs from the oil-producing glands of the skin. They are pink and hairless and sometimes rupture, causing a mild infection. The older the dog, the more of these oil gland tumors will form.

Remember, not all cancerous tumors can be cured, but the right treatment can help keep your beloved pet comfortable and give them more time by your side.

Tumors in Dogs and Cats; Are They Cancer?