Canine Mast Cell Tumor Diagnosis

A canine mast cell tumor is a form of cancer that is serious, but is usually easily removed. They make up to 20% of tumors in dogs and can affect a dog’s lifespan and quality of life if left untreated.

Mast Cell Tumors Explained

Mast cell tumors are found as masses in a dog’s skin or other tissues of the body. Their danger lies in the fact that the mast cells affect a dog’s immune system and release and excess of chemicals such as heparin, serotonin, prostaglandins, histamines, and other enzymes.

The sizes of the tumors vary along with their appearance and shape and cannot be diagnosed without particular tests. After a diagnosis is made, tumors are then graded as a 1 or 2 and are staged on a scale of 0 to 4: 0 being the least severe form of tumor and 4 being the stage where the tumor has spread, involving a dog’s lymph nodes.

The exact cause of mast cell tumors in dogs is not known, but veterinarians have seen dogs of all ages and breeds develop this form of cancer.

Diagnosing Canine Mast Cell Tumors

Diagnosing a mast cell tumor begins at home when a pet owner notices a growth on her dog and takes him to a veterinarian’s office. If a growth is not seen, the dog may present with symptoms that cause worry to a dog owner such as vomiting or blood in a dog’s stool. A veterinarian may refer the dog owner to a veterinary oncologist or perform a variety of diagnostic tests himself.

A fine needle biopsy or aspiration is typically performed first. This is a simple procedure where a veterinarian inserts a thin needle into a dog’s tumor, sometimes with the guidance of an ultrasound machine, and collects fluid from within the mass. The fluid is then studied under a microscope to see the make-up of the cells collected. If it is determined the sample collected is part of a mast cell tumor, the tumor may then be removed so a more in-depth biopsy can be performed. A dog’s lymph nodes may also be aspirated for diagnostic purposes.

Blood tests will be performed along with the fine needle aspiration. These tests will include a CBC (complete blood count), a buffy coat to see if the bone marrow has been affected, and a serum chemistry profile. The blood work will show the levels of white blood cells, platelets and the levels of mast cells.

It is not unusual for a veterinarian to test a sample of a dog’s urine or bone marrow, get x-ray images, and an ultrasound of the tumor. These tests can help a veterinarian determine the stage and level of the mast cell tumor, which will guide to decision on how to treat the growth.

Mast cell tumors, being one of the most common tumors in dogs, are one of the more understood conditions in veterinary oncology. For the best prognosis, a dog owner should be attentive to her dog’s health and get any new or unusual lumps looked at by a veterinarian.