Vet’s 2025 Guide to Canine Soft Tissue Sarcoma 🩺 Diagnosis, Treatment & Prognosis

By Dr. Duncan Houston BVSc

💡 What Is Soft Tissue Sarcoma?

Soft tissue sarcoma (STS) refers to a group of malignant tumors arising from connective tissues—muscle, fat, blood vessels, nerves, or fibrous tissue. They’re most common under the skin and make up ~8–15% of canine skin/subcutis tumors.

🚩 Who Gets It & Risk Factors

• 🐶 Mostly in middle-aged to older dogs.
• 🔎 Large breeds—Boxers, Golden Retrievers, Great Danes, Bernese—are predisposed.
• 📦 Chronic inflammation or foreign material (like implants), radiation exposure may contribute.

👀 Signs & Locations

• 🟣 A firm, slow-growing lump under skin/trunk, limbs, head, mouth.
• 🦴 Occasionally painful if invading bone or nerves.
• 🌡 If oral or abdominal, signs include bad breath, drooling, diarrhea, and weight loss.

🧪 Diagnosis & Staging

1. FNA or biopsy: tissue sample examined under a microscope to confirm sarcoma type.
2. Histologic grading: Grade I (low) to III (high), based on appearance and mitotic rate. Low grades less likely to spread (<10%), high-grade up to 25–40% metastasis risk.
3. Imaging: chest x‑rays, ultrasound, CT/MRI to check for spread (lungs, local structures).
4. Local assessment: evaluate involvement of fascia, bone, nerves—impacts surgical plan.

🛠 Treatment Options

1. Surgery (Wide Excision)

• ✂️ First-line treatment—remove tumor with wide margins of healthy tissue to reduce recurrence.
• 📈 Local recurrence occurs in 7–30% post-surgery; reduced with clean margins and radiation.

2. Radiation Therapy

• 🎯 Adjuvant radiation recommended if the margins were incomplete or tumor in difficult location.
• ⌛ Can also be used pre-surgically to shrink tumors, or palliatively to reduce discomfort.

3. Chemotherapy

• 💊 Suggested for high-grade (Grade III) tumors or metastatic cases.
• 📌 Common drugs include doxorubicin, cyclophosphamide, ifosfamide—best used when microscopic disease remains.

4. Additional Therapies

• ⚡ Emerging options: electrochemotherapy, immunotherapy (immunogenic cell death); clinical trials are underway.

📊 Prognosis & Survival Prospects

• ✅ Grade I/II completely excised: excellent prognosis; 3‑year survival possible.
• ⚠️ Grade III or incomplete excision: guarded prognosis; median ~12 months; up to 18 months with aggressive therapy.
• 📉 Metastasis risk similar—lungs most common site; regular surveillance x‑rays essential.

🔍 Follow-up & Monitoring

• 📆 Recheck every 3‑4 months in first year, then every 6 months for two years.
• 📷 Monitor for recurrence—check incision site and capture images in Ask A Vet app.
• 🩻 Thoracic imaging to detect early metastasis.

🏡 Ask A Vet App Home‑Support Tools 📲🐶

• 📆 Medication & appointment reminders (surgery, radiation, chemo schedules).
• 📸 Upload tumor and incision photos—track healing and notice changes.
• 📊 Log limb function, appetite, breathing—alert for issues.
• 🔔 Triggers for vet notification: swelling, respiratory changes, lameness.
• 📚 Access guides: surgical prep, palliative care, post‑radiation skin care.

🔑 Key Takeaways 🧠✅

• STS originates in connective tissues and varies widely in type and aggressiveness.
• Diagnosis depends on biopsy, grading, and imaging for staging.
• Wide-excision surgery remains core treatment; radiation/chemo support high‑risk cases.
• Prognosis is best for low-grade, fully resectable tumors; surveillance vital to catch recurrences early.
• Ask A Vet brings home-monitoring, digital support, and vet collaboration to empower owners.

🩺 Final Thoughts ❤️

In 2025, STS in dogs is manageable when caught early and treated comprehensively. A combination of surgery, radiation, and sometimes chemotherapy helps extend high-quality life. Owners play a pivotal role—regular check-ins, monitoring through Ask A Vet, and consistent veterinary follow-up ensure the best outcomes. With modern oncology and smart care tools, many dogs beat the odds and thrive. 🐾✨

Visit AskAVet.com and download the Ask A Vet app to track lumps, manage appointments, upload healing photos, set alerts, and collaborate with oncology teams anytime. 📲🐶