What are feline mammary tumours?

Feline mammary tumours are a type of cancer that affects the mammary glands in cats. These tumours can develop in one or multiple mammary glands and can spread to other parts of the body (mostly lungs +/- lymph glands) if left untreated. The exact cause of feline mammary cancer is unknown, but there are several risk factors that have been identified, including:

• Age: The risk of developing mammary carcinomas increases as a cat gets older.
• Spaying: Female cats that have been spayed before their first heat cycle have a much lower risk of developing mammary carcinomas compared to those that have not been spayed.
• Hormones: Hormonal imbalances either produced by the body or external use of hormones can increase the risk of mammary carcinomas in cats.

The most common types of feline mammary tumours include:

• Carcinomas: This is the most common type of mammary carcinoma in cats. It is typically found in the glands of the mammary tissue and the majority of the time aggressive.
• Sarcomas: This type of mammary tumour is less frequent but also aggressive and tends to spread quickly to other parts of the body.

Symptoms of feline mammary carcinomas may include:

• Lumps or masses in the mammary glands
• Discharge from the mammary glands
• Changes in the appearance of the mammary glands
• Loss of appetite
• Weight loss
• Decreased activity levels

Diagnosis

Diagnosis of feline mammary tumours typically involves a combination of physical examination, radiographs, ultrasound or CT scan +/- needle biopsies. A biopsy of the mass can confirm the presence of cancer and determine the type of mammary tumour present.

Treatment

Treatment of feline mammary carcinomas may include:

• Surgery: This is the most common form of treatment for feline mammary carcinomas. The affected mammary gland(s) is typically removed, along with some surrounding tissue (+/- lymph glands). Frequently the treating Oncologist might suggest removing all the mammary glands on the same side of the tumour to avoid future recurrence or spread.
• Chemotherapy: This type of treatment uses drugs to kill cancer cells. Chemotherapy is commonly used in conjunction with surgery or less commonly as a standalone treatment for feline mammary tumours. Depending on the type of cancer and the treatment intent most commonly injectable chemotherapy is used but also oral chemotherapy can be an option (metronomic chemotherapy).

What is feline fibroadenomatous hyperplasia?

Apart from malignant feline mammary tumours, there is also a rare condition called feline fibroadenomatous hyperplasia.

Feline fibroadenomatous hyperplasia is a benign condition that affects the mammary glands in cats. It is characterized by the growth of fibrous tissue in the mammary glands, which can cause the glands to enlarge. The exact cause of feline fibroadenomatous hyperplasia is unknown, but it is thought to be related to hormonal imbalances and more particularly internal or external exposure to progesterone.

Symptoms of feline fibroadenomatous hyperplasia may include:

• Enlargement of the mammary glands
• Tenderness or discomfort in the mammary glands
• Changes in the appearance of the mammary glands

Diagnosis of feline fibroadenomatous hyperplasia typically involves history (a cat that recently had a hormone injection to control the heat cycle or pregnant cat), physical examination, radiographs, ultrasound, and biopsy. A biopsy of the mass can confirm the presence of fibrous tissue in the mammary glands.

Treatment of feline fibroadenomatous hyperplasia may include:

• Stopping external progesterone use.
• Surgery: Spay can be considered if the cat is pregnant and the pregnancy is not desirable. Surgical excision of the affected gland (s) can be considered in cases that are not improving with spay or medical management.
• Medical management with progesterone receptor blockers in case of endogenous progesterone production: That injection can relieve the swelling from mammary glands but can also terminate the pregnancy.

If you have any further questions, please do not hesitate to contact the hospital.