November is National Pet Cancer Awareness Month. Today we focus on mast cell tumors (MCT), the most common malignant skin tumor in dogs and which can also affect cats. In a brief summary,ย The Meowing Vetย raises awareness on the common clinical signs that can indicate that your pet has a mast cell tumor, how it is treated, and why a veterinary physical exam is so important.
Learn more below…
Mast cell tumors (MCT or mastocytoma), the most common malignant skin tumors in dogs, arise from the unregulated proliferation of cancerous mast cells. These blood cells typically function in the immune system. While any dog breed can be affected, certain breeds are predisposed, including boxers, Boston terriers, pugs, bulldogs, and retrievers.
(image property of Clinician’s Brief)
Mast cell tumors are known as the โgreat pretenderโ for their tendency to take on various appearances (colors, shapes, and sizes) in a variety of locations on the body, even affecting the bone marrow, spleen, liver, and gastrointestinal tract. Mast cell tumor development (or mastocytosis) of the GI tract can lead to decreased appetite, weight loss, vomiting and diarrhea, and black stool (melena) due to ulcers. Mast cell tumors of the skin may wax and wane in size. They can also be very itchy and painful or bleed, and your pet may develop hives. This occurs due to the release of various molecules from the mast cells when they degranulate, releasing the products histamine and heparin. Histamine is also released when we have an allergic reaction, such as to a bee sting. In some instances, an aggravated mast cell tumor can release enough histamine to trigger a severe response, causing low blood pressure and difficulty breathing.
If you notice an odd mass or signs of illness in your dog, visit your personal veterinarian ASAP. Yearly check-ups will allow your vet an opportunity to conduct a physical examination in the hopes of detecting a mast cell tumor (or other tumor) as early as possible before it has the chance to grow or spread.
(image property of Clinician’s Brief)
Diagnosis of a mast cell tumor is made via aspiration (fine needle aspirate), or placing a needle on a syringe into the tumor to obtain a sample for examination of cells under a microscope. Your vet will administer injectable diphenhydramine (Benadrylยฎ) to your dog prior to aspiration to prevent the tumor from releasing histamine when manipulated.
Surgery is the best method of treatment and can be curative if caught early. If not, these tumors can spread and metastasize. Cases affecting the GI tract require radiation and/or chemotherapy.
Have you heard about the new intra-tumoral injection to treat MCT? Ask your vet about STELFONTAยฎ (tigilanol tiglate injection), an effective treatment for non-metastatic mast cell tumors in dogs.
Cats can be affected too, especially Siamese cats. Mast cell tumors are the second most common skin tumor in cats, yet half of feline mastocytosis cases are internal, affecting the intestines, liver, spleen, and lymph nodes. Surgical removal as well as chemotherapy is recommended.
Read The Meowing Vet’s previous article to learn more about the basics of cancer in pets, including the top warning signs that your pet may have cancer, the most common cancers affecting dogs and cats, how cancer is diagnosed and staged, and the different treatment options available for canine or feline cancer.
– Maranda Elswick, DVM
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This article originally appeared as a post on The Meowing Vet’s Instagram profile, @themeowingvet (July 26, 2017).
