Veterinary Oncology: Lumps and Bumps

October 23, 2019

Veterinary Oncology: Lumps and Bumps

If you have ever felt a lump under your pet’s fur while petting her, you likely experienced a sinking feeling. Worry creeps in as you wonder about the type of mass, and whether the lump is cancerous. If your family veterinarian does diagnose cancer, the Oncology department at CASE will work with her to design a treatment plan that gives your beloved pet the best quality, and quantity, of life possible.

What should I do if my pet has a mass?

If you have noticed a lump, bump, or swelling on your pet, you should have it evaluated as soon as possible by your primary veterinarian, who will collect important information, including:

  • Duration — Knowing how quickly a mass has increased in size can be helpful. Some masses develop suddenly and grow quickly, whereas others can be present for years without growing.
  • Size — A measurement of your pet’s mass taken during an initial visit can be compared with future measurements to see how quickly it is growing.
  • Color — The color of a mass on the skin surface can sometimes help determine its origin.
  • Abnormal characteristics — If a mass is ulcerated, bleeding, or has other significant characteristics, these details will be noted in the medical record.

How will my veterinarian diagnose the type of mass in my pet?

Masses found on pets can be benign or malignant (i.e., cancerous). Although benign tumors are noncancerous, some can aggressively invade nearby tissue and interfere with normal function. Some malignant masses metastasize, or release cells into circulation that can spread cancer to other body parts. 

Your pet’s mass type cannot be diagnosed on a simple exam. Your veterinarian will take a sample of the mass so diagnostic testing can determine the growing cell type. Two procedures commonly used for identification include:

  • Fine needle aspiration (FNA) — During an FNA, a needle is inserted into the mass, and a syringe is used to aspirate, or suction, cells that are microscopically identified. Diagnosis via FNA can be limited, because many masses are not uniform in composition, and some may contain fluid pockets. If the needle does not collect cells that make up the mass, an accurate diagnosis may not be reached. 
  • Surgical biopsy — A biopsy provides a larger sample of the mass that can be sent to a diagnostic laboratory for microscopic evaluation. A biopsy typically yields a more reliable diagnosis, and if the mass is malignant, pathologists may also be able to determine how aggressive the cancer is.

After diagnosis, your veterinarian may perform further testing to determine whether a cancerous mass has metastasized, or if an invasive mass has affected nearby tissues. She may also refer you to our oncology department for further diagnostic testing, such as a computerized tomography (CT) scan.

What mass types are common in pets?

Animals develop many of the same tumors that affect humans. Common mass types include:

  • Lipomas — Also known as fatty tumors, lipomas are benign masses that commonly develop in many dog breeds. Lipomas rarely require treatment unless they grow in an area that restricts normal function.
  • Histiocytomas — Histiocytomas typically appear as small, raised, hairless masses in dogs younger than 3 years of age. They are benign, often regress on their own in a few months, and seldom require surgical removal unless the mass is bothersome.
  • Melanomas — Melanomas are a neoplasia of pigment-producing cells that often form as black or dark brown skin masses. Melanomas are usually malignant and aggressive, especially if they develop in a toe-nail bed or the mouth. Metastasis to the lymph nodes or lungs is common, and prognosis is often poor. 
  • Mast cell tumors (MCTs) — Mast cells are immune cells that are normally involved in allergic reactions. MCTs on the skin typically grow quickly, become easily irritated, and release histamine that causes itching and redness. Boxers are predisposed to MCT development, which can occur at any age. MCTs can be aggressive, and require prompt treatment.
  • Mammary gland carcinomas — Mammary masses are common in female dogs and cats who are intact, or who were spayed after experiencing several heat cycles. In dogs and cats, 50% and 80% of mammary masses, respectively, are malignant.
  • Lymphoma — Lymphoma is a cancer of lymphocytes, which are a white blood cell type. Many lymphoma cases cause swollen lymph nodes that can be seen under your pet’s jaw, near her shoulders, and behind her knees.
Cancer in Pets

How will my pet’s mass be treated?

No two pets are the same, and neither are their cancers. Our board-certified veterinary oncologists are trained to treat every pet’s case individually, and will devise a specific treatment plan for her situation. Treatment may include:

  • Surgery — CASE’s board-certified surgeons work with our oncology team to completely excise cancerous masses or debulk a portion of a large, bothersome mass.  
  • Chemotherapy — Chemotherapy is the use of medications to slow cancer growth or kill invading cells. Chemotherapy may be used for cancers that cannot be surgically excised, or after surgical removal to kill cancer cells that may have spread from a primary mass. 
  • Radiation — Radiation uses a focused beam to break the DNA inside cancer cells so that they die and can no longer multiply. Radiation can be used to eliminate a mass, shrink a tumor prior to surgical excision, or decrease tumor size in patients who cannot undergo surgery, or for whom a cure is not possible.  

We know that finding a lump or bump on your pet is scary. Contact us with questions about your pet’s mass or to schedule a consultation with our oncology department.