Affection aids in the diagnosis of tumors in dogs and cats; understand

Affection aids in the diagnosis of tumors in dogs and cats; understand
Affection aids in the diagnosis of tumors in dogs and cats; understand (Photo: Freepik)

If lumps appear on the limbs or trunk of your little dog or, a bit more rarely, on the kitten, schedule a veterinary appointment without delay, even if they are small bumps: it could be mast cell tumor!

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Mast cell tumor is a malignant neoplasm derived from the mutation of cells called mast cells, which originate in the bone marrow. This mutation leads to the uncontrolled proliferation of these cells. Veterinary Clarisse Teixeira, specializing in Oncology at the Veterinary Hospital Taquaral (HVT Campinas), explains that the highest incidence of mast cell tumors is in the skin, where single or multiple nodules may appear.

According to her, these cells are present in the digestive system and lungs, but it is in the dermis and subcutaneous tissue that they are more abundant. According to Dr. Clarisse, mast cells are cells of the immune system and play an important role in the host’s defense against parasitic infections and allergic reactions. “One of the most severe forms is systemic mastocytosis, which is a marked increase in mast cells in the bone marrow, lungs, or stomach,” she emphasizes.

The veterinarian emphasizes that some authors suggest that the development of mast cell tumors may be associated with chronic inflammation, topical carcinogens, hereditary factors, genetic alterations, and viruses. But its cause is still unknown. Usually, the disease affects animals over eight years of age.


Symptoms depend on the location of the neoplasm, and the behavior of this neoplasm is quite varied, being a single or multiple, aggressive, and malignant nodule. “These nodules can ulcerate and also cause itching,” says Clarisse.

The veterinarian also lists other symptoms, such as gastrointestinal ulceration that causes vomiting with or without blood, bleeding, and diarrhea.

More common in dogs than in cats, brachycephalic breeds are more affected, but it also occurs in Boxer, Boston Terrier, Bulldog, Labrador, Golden Retriever, Schnauzer, Pit Bull, and mixed-breed (mongrel) dogs. As for cats, the predisposed breed is the Siamese. However, there are some studies reporting no preference for sex or age.


The diagnosis is made through cytology and histopathological examinations. It is important to grade the mast cell tumor to assess the biological behavior of this tumor and thus choose the best treatment option. This factor indicates the risk of recurrence or death of the patient.


Dr. Daniela Formaggio, specializing in felines and veterinary oncology, points out that the main therapeutic modality for mast cell tumors is surgery. She emphasizes that there is also electrochemotherapy, chemotherapy, and radiotherapy. “These modalities can be combined depending on the location, extension, and grade of the tumor,” she considers.

Side effects are related to chemotherapy and include nausea, vomiting, loss of appetite, diarrhea, and immunosuppression. “The success rate is directly related to the size and location of the tumor and its histological grade,” notes Dr. Daniela.


The doctors affirm that there are no measures to prevent the onset of mast cell tumors. The size of the tumor is directly related to the chances of success in the first intervention. “This applies to most neoplasms, but in the case of mast cell tumors, an early approach is essential,” warns Daniela.

According to the veterinary oncologist, through routine inspection, it is possible to detect any nodules that appear on the animal’s body.

“Animals with a history of skin allergies should receive special attention, as constant inflammation can lead to the mutation of mast cells,” she emphasizes.

Dr. Daniela draws attention to the pet’s nutrition. “Ensure appropriate caloric intake to maintain the correct weight and preserve muscle mass,” she says. Clarisse recommends omega-3 series fatty acid supplements. “They are important nutraceuticals for oncologic treatment. They help minimize the loss of muscle mass associated with sarcopenia and cachexia,” she explains.

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