Mammary Gland Tumours In Dogs And Cats

Mammary gland tumours are more common cancers in female dogs and cats, especially those that are unspayed or spayed later in life. Up to 50% of dog mammary tumours are malignant, with carcinomas being the most frequent type. In cats, the disease is even more aggressive. Approximately 80–90% of mammary tumours are malignant, often presenting late and progressing rapidly.

Hormonal influence plays a significant role: early spaying dramatically reduces the risk, while intact females or those spayed after multiple heat cycles are more predisposed. Because of their frequency and potential for metastasis, early detection and accurate staging are essential in shaping effective treatment strategies.

Mammary tumours usually appear as firm nodules or masses in one or more glands. In dogs, they may present singly or as multiple nodules, while in cats, they often appear as chains of aggressive tumours. Clinical features include:

• Palpable lumps in one or more mammary glands.
• Ulceration or inflammation in advanced cases.
• Regional lymph node involvement in higher-stage disease.
• Metastasis to the lungs and beyond if not detected early.

Diagnosis requires histopathology (biopsy) to determine the tumour type and grade. Staging often includes thoracic radiographs, abdominal ultrasound, and lymph node evaluation. However, these conventional methods can underestimate metastatic spread.

PET-CT offers higher accuracy beyond conventional imaging, providing functional and anatomical details. This is especially important in mammary gland tumours, where metastasis risk is high and treatment decisions hinge on staging accuracy.

The key benefits of PET-CT include:

• Early detection of metastases. The PET-CT scan identifies small or hidden metastases in lungs, liver, or lymph nodes that may be missed by standard imaging.
• Treatment planning. It helps differentiate viable tumour tissue from inflammation or scarring, guiding surgical margins and decisions on lymph node removal.
• Radiation targeting. PET-CT scans highlight metabolically active tumour regions, allowing radiation oncologists to deliver highly focused therapy.
• Response monitoring. The PET-CT scan detects metabolic changes after chemotherapy or targeted therapies, often before structural shrinkage is visible on CT or ultrasound.

A PET-CT scan offers advanced prognostic insights. It helps stratify cases into those where aggressive treatment is justified and those where palliative care may be more appropriate.

Mammary gland cancers carry an emotional weight for pet owners. Providing clear, evidence-based information about the extent of disease and likely outcomes is invaluable. PET Theranostics provides veterinarians with the most advanced imaging, diagnostics and reporting available, ensuring treatment plans are based on the best possible information. We are currently accepting referrals. Referral forms are available online here.