Lumps and bumps on your pet

Lumps & Bumps

Skin lumps are one of the most frequently reported problems on our patients, presenting in a range of shapes and sizes. Some lumps are benign (slow growing and usually harmless), and others are malignant (fast growing and able to spread). It is hard to know when the lumps are concerning and should be seen by a vet, so here are a few facts to remember:

  1. The size of a lump does not make it more dangerous; small lumps can often be more cancerous than large lumps
  2. No lumps have a ‘typical look’; all lumps require sampling to determine what cells are present
  3. Lumps that do not hurt should still be considered for removal
  4. Most lumps do not go away, and most vets prefer to cure the problem and remove the lump rather than ‘wait and see’. We like to know what we are dealing with rather than ignore it.

Take 5 minutes now to check over your pet from top to tail. Ensure you check ears, nose, belly, between toes, and even inside the mouth.

What we can do if you find a lump…

A consultation with your pet allows us to examine the lump and determine if it requires sampling. A fine needle aspirate in the consult allows us to collect a few cells from the lump to examine under the microscope to see if there are immediate concerns. Although fine needle aspirates have their limitations it is often useful for identifying what most lumps are. Alternatively, biopsy of the lump can also be performed under heavy sedation or general anaesthesia and the sample sent to an external laboratory for examination. If the lump is dangerous and requires removal, then depending on the location, complete excision under general anaesthesia of the lump can be performed.

The most common lumps seen on pets

In dogs the most common tumours to occur include:

Papilloma (Wart)

Papillomas are benign tumours of the skin. They are small and hard and can bleed if damaged. Thy can be left or surgically removed.


Lipomas are benign fatty tumours. They vary in size and shape and are usually slow growing. They may require removal if they interfere with mobility or are very fast growing.

Soft tissue sarcomas

These masses are often solid with varying size, and can be difficult to diagnose from a fine needle aspirate. Only a few metastasis but local recurrence can be a problem if wide surgical margins aren’t obtained

Mast cell tumours

These tumours are called the “great pretenders” as they have a variable appearance. Usually a diagnosis can be made on fine needle aspirate. Mast cells can also be graded from low (able to be surgically removed) to high (likely spread around the body) -grade tumours which indicates their prognosis. Other tests may be required if the tumour is high grade


These tumours are mainly in young dogs. They develop really quickly, and can be ulcerated. They are usually benign and may spontaneously regress.

Squamous cell carcinoma

These are firm nodular masses which can be raised or erosive. Sites exposed to the sun are most at risk. The majority of tumours have a good prognosis with wide surgical excision.


These tumours can vary from flat pigmented areas to raised nodules. Most skin melanomas are benign except for the ones on the digit. Melanomas found in the mouth are malignant, and require the local lymph FNA and chest radiographs (screening for tumour spread). Usual treatment is removal with wide margins, but not if there is metastatic disease.

Cystic Tumours

Most cystic tumours are benign. Then they rupture they can cause a lot of inflammation requiring surgical excision.

Sebaceous Gland Tumours

These are often misdiagnosed as sebaceous cysts. These tumours range from benign o malignant (rapid growing and spread). Most lesions require surgery.

The most common lumps in cats include….

Squamous Cell Carcinoma

These are common around the head, the ears, nose and eyelids where the skin is not pigmented and exposed to the sun. These can be ulcerated and rarely spread.

Basal Cell Tumours

These are the most common skin tumour in middle-aged to older cats. They are benign tumours usually on the head and neck, well demarcated, small and firm. They often require surgery to remove.