Soft Tissue Sarcoma in Dogs and Cats: Signs, Grades, and Treatment

What is soft tissue sarcoma in dogs and cats?

Soft tissue sarcoma (STS) is a group of malignant tumours that arise from connective tissues — including fat, muscle, nerves, and fibrous tissue — beneath the skin or within body cavities. In both dogs and cats, STS tumours are locally invasive, meaning they push deep roots into surrounding tissue even when the surface lump appears small. MaxPetz in Delhi provides veterinary cancer care for pets diagnosed with or suspected of having soft tissue sarcoma.

STS accounts for a significant proportion of skin and subcutaneous tumours seen in dogs, and a smaller but clinically important proportion in cats. Early identification and grading are critical because treatment outcomes depend heavily on how advanced the tumour is at diagnosis.

What are the early signs of soft tissue sarcoma in dogs and cats?

Soft tissue sarcomas often present as a painless, slow-growing lump under the skin. Because they are not always painful in early stages, owners may not notice them until the tumour has grown considerably. Knowing what to look for helps prompt earlier veterinary assessment.

Common signs to watch for:

• A firm or soft lump beneath the skin, most commonly on the limbs, trunk, or head
• A lump that feels attached to deeper tissue rather than moving freely
• Gradual increase in lump size over weeks to months
• Skin ulceration or discharge over the lump in advanced cases
• Lameness or reduced limb use if the tumour is near a joint or nerve
• Swelling that returns after apparent resolution (a hallmark of incomplete removal)
• In late-stage disease: weight loss, lethargy, reduced appetite, or difficulty breathing if spread to the lungs

What are the grades of soft tissue sarcoma in pets?

Histological grading — performed on a tissue biopsy — is the single most important factor in predicting how a soft tissue sarcoma will behave. Grading assesses cell differentiation, mitotic rate (how fast cells are dividing), and the degree of tumour necrosis.

Grade I and II tumours together represent the majority of STS cases in dogs. Grade III tumours are less common but carry a more guarded prognosis. In cats, injection-site sarcomas (a specific subtype) are typically high-grade and require aggressive management.

What are the treatment options for soft tissue sarcoma in dogs and cats?

Treatment planning for STS depends on tumour grade, location, size, and whether spread (metastasis) has occurred. A combination of approaches is often used. The goal for low- and intermediate-grade tumours is typically curative; for high-grade tumours, the goal may shift toward disease control and quality of life.

Primary treatment options include:

1. Surgical excision — The cornerstone of STS treatment. Wide surgical margins (removing a cuff of normal tissue around the tumour) are essential. Incomplete margins are the leading cause of local recurrence. For limb tumours, limb-sparing surgery may be possible in selected cases.
2. Radiation therapy — Used after surgery when margins are incomplete or narrow, or when the tumour location makes wide excision impossible. Can also be used as a primary treatment to reduce tumour size before surgery.
3. Chemotherapy — Generally reserved for high-grade (Grade III) tumours or confirmed metastatic disease. It is not routinely used for low- or intermediate-grade STS.
4. Palliative care — For pets where curative treatment is not pursued, pain management and supportive care can maintain quality of life.

Pre-surgical staging — including chest radiographs and lymph node assessment — is recommended to check for spread before committing to a treatment plan.

When should you bring your pet to a veterinarian for a lump?

Not every lump requires emergency attention, but certain signs warrant prompt veterinary assessment rather than a wait-and-see approach. As a general rule, any lump that meets one or more of the following criteria should be evaluated without delay:

• The lump has been present for more than 4 weeks
• The lump has grown noticeably within 2–4 weeks
• The lump is larger than 1 cm in diameter
• The lump feels firm and appears attached to underlying tissue
• The skin over the lump is ulcerated, discharging, or discoloured
• Your pet is showing lameness, pain, or behavioural changes alongside the lump
• A previously removed lump has returned at the same site

In cats specifically, any lump at a previous vaccination or injection site — regardless of size — should be assessed promptly given the known risk of injection-site sarcoma at those locations.

Early-stage soft tissue sarcomas are more amenable to complete surgical removal with clean margins. Delaying assessment allows the tumour to grow deeper into surrounding tissue, making curative surgery more difficult.

How does MaxPetz in Delhi approach soft tissue sarcoma in pets?

MaxPetz in Delhi offers veterinary cancer care combining clinical assessment, diagnostic workup, and treatment planning for pets with soft tissue sarcoma. The approach integrates cutting-edge technology with compassionate service, ensuring each pet's case is evaluated individually — from initial lump assessment and biopsy through to surgical planning and post-operative monitoring.

Owners concerned about a lump on their dog or cat can use the booking form on this page to arrange a consultation. The clinical team will guide you through the diagnostic steps — including fine-needle aspiration, histopathology, and staging — before recommending a treatment pathway suited to your pet's grade and overall health status.

For questions about veterinary oncology services at MaxPetz Delhi, or to understand what a cancer care consultation involves, use the booking form on this page or speak with the team directly.