🐱 Veterinary Guide to Mammary Tumors in Cats: Diagnosis, Treatment, and Prevention in 2025 🩺

By Dr. Duncan Houston, BVSc

🔍 Understanding Mammary Tumors

Mammary tumors are the third most common cancer in cats, with around 90% being malignant. Most cases occur in female cats aged 10–12, especially if they were unspayed or spayed later in life. These tumors often begin as small, firm lumps in the mammary glands and can progress aggressively if untreated.

💢 Tumor Progression

• 🎯 Tumors can feel like pebbles and are best removed early
• ⚠️ Left alone, tumors grow, harden, ulcerate, and become infected
• 🩸 Spread occurs to local lymph nodes, chest, and organs such as brain, bone, and spleen

📊 Tumor Size & Prognosis

• 📏 Tumors < 2 cm: Median survival ~4.5 years
• 📏 Tumors > 3 cm: Median survival ~6 months

Radiographs and blood tests are essential before surgery to assess spread and overall health.

⚠️ Risk Factors

• ♀️ Female sex (most significant factor)
• 🐾 Siamese breed (earlier onset, more aggressive tumors)
• 💊 Hormonal exposure (e.g., past progestin use)

🛡️ Protective Measures

• 🚫 Early spaying is key:
• Before 6 months: 91% risk reduction
• Before 1 year: 86% risk reduction
• Before 2 years: 11% risk reduction
• 👶 Having kittens does not protect against tumors

🔬 Tumor Types & Grading

Most tumors are carcinomas or adenocarcinomas. Grading (I, II, III) indicates severity:

• Grade I: High 1-year survival
• Grade II: 57% survival (increased with chemo)
• Grade III: No survivors at 1 year with surgery alone

🩺 Treatment: Surgery

Surgical removal is essential. Optimal approach involves:

• 🩻 Removing the entire chain of mammary glands
• 🔄 Staged surgery: One side at a time, 3–5 weeks apart
• 🎯 If advanced disease is present, focus may shift to comfort (palliative care)

Results:

• 1-year disease-free in 50% of cats
• 2-year disease-free in 32%
• If lymph node involvement: 5.5-month disease-free interval

💊 Treatment: Chemotherapy

Chemotherapy improves outcomes after surgery. Common drugs include:

• Adriamycin (doxorubicin)
• Cyclophosphamide

In cases with metastasis or incomplete removal:

• 💊 50% of cats respond
• ⏳ Median survival: 150–180 days (with chemo) vs. 75–86 days (without)

💔 When to Consider Euthanasia

Two primary reasons:

• 🩹 Ulcerated, infected tumors causing pain and distress
• 🫁 Spread to lungs, leading to respiratory failure

Quality of life decisions are personal but can be guided by veterinary input and quality of life assessment tools.

📋 Summary for 2025

• 🧬 90% of feline mammary tumors are malignant
• 🎯 Early detection and surgery drastically improve outcomes
• 🚫 Spay before 6 months to reduce risk by 91%
• 🔄 Combined surgery and chemotherapy extend survival

📱 Need Guidance?

If you’ve noticed a lump or want to discuss spaying or treatment options, visit AskAVet.com or use the Ask A Vet app to connect with a licensed vet today. 🐾💖