Discovering a lump on your dog or cat’s body can be unsettling. You worry and start asking yourself a thousand questions, and that’s completely normal. The good news is that masses in or under the skin are common in pets (it is estimated that 30 to 50% of dogs and cats will develop at least one during their lifetime). Here’s some useful information about them.

When should you consult a veterinarian?

If the lump is the size of a pea (about 7 mm or ¼ inch) or smaller and has been present for less than a month, it is generally reasonable to monitor it.
However, it is important to consult your veterinarian if:

• the lump is still present after a month;
• it is growing rapidly;
• it changes shape, appearance, or colour;
• it oozes or bleeds;
• it seems to bother your pet (itching, excessive licking, pain, etc.).

Does a lump necessarily mean cancer?

Finding a lump can be a source of anxiety, but it is important to remember that a lump does not automatically mean cancer. Conversely, it is impossible to determine the nature of a lump simply by looking at it or feeling it.

Fortunately, there are simple and minimally invasive tests that can identify the type of lump and help guide appropriate treatment.

Diagnostic tests: how can a lump be identified?

The first recommended test is often a fine needle aspiration. Using a small needle, cells are taken directly from the lump. This test is quick, usually painless, and does not require anesthesia. The samples are sent to a laboratory for cytology, where a pathologist examines the cells under a microscope.

Results are usually available within a few days. They provide a diagnosis in about 70% of cases, including identifying the type of mass, not just whether it is benign or cancerous.

When cytology does not provide enough information, a biopsy may be recommended. A small fragment of the mass is then removed under anesthesia or deep sedation. Results are usually available within a week and provide the most complete level of information.

Depending on the situation, additional tests may be recommended to assess your pet’s overall health and, in the case of cancer, to check whether it has spread (metastases). These tests may include:

• a blood test;
• a urine test;
• medical imaging (X-rays, ultrasound, and/or CT scan);
• a fine needle aspiration of the lymph nodes.

Treatment: does a mass always need surgery?

Once a diagnosis has been made, the veterinarian will recommend the most appropriate treatment. Surgery is often the first option, especially when the mass can be completely removed.

• For benign masses, it may be sufficient to remove only the mass itself.
• For malignant masses, it is often necessary to remove additional tissue around and beneath the mass to maximize the chances of eliminating all cancer cells.

However, surgery is not always the only option.

• For some small benign masses, alternative treatments such as cryotherapy (freezing the mass) may be considered.
• In some cases, simple monitoring is recommended, especially if the mass is benign, stable, does not affect the animal’s health, and does not cause discomfort. Some masses may even regress spontaneously without intervention.
• For cancerous masses, additional treatments may sometimes be necessary, either alone or in combination with surgery. These may include chemotherapy, radiotherapy, or specific medications.

In conclusion, discovering a lump on your pet can be worrying, but a prompt and appropriate evaluation allows for an accurate diagnosis and the best possible treatment. If you are unsure, never hesitate to consult your veterinarian!