TL;DR: A rapidly growing hard lump on a dog could indicate an infection or a serious tumor and should be evaluated by a veterinarian within 24 to 48 hours.
What could it mean if my dog has a rapidly growing hard lump?
Finding a firm mass on your dog that appears to be increasing in size daily can be very stressful. Potential causes for such a growth include:
- Inflammatory responses like an abscess or an infected cyst
- Neoplastic growths such as mast cell tumors or soft tissue sarcomas
- Aggressive conditions that cannot be accurately diagnosed through touch alone
Is a rapidly growing hard lump on my dog considered a veterinary emergency?
The urgency level for a rapidly growing hard lump is categorized as Medium. You should follow these action steps:
- Schedule a veterinary appointment within the next 24 to 48 hours.
- Seek immediate emergency care if the lump is bleeding profusely or your dog is having trouble breathing.
- Address the growth promptly, as rapid expansion can indicate a high-grade tumor or active infection.
How can taking a photo of the lump help my veterinarian?
When you contact your veterinary clinic, providing a clear, well-lit photo of the lump is incredibly helpful for the triage process:
- It allows the team to see the exact location and the color of the overlying skin.
- It helps identify signs of ulceration.
- Placing a common object like a coin next to the lump for scale provides a baseline measurement to track how fast the mass is expanding.
Clinical Context (Merck Veterinary Manual)
Cutaneous neoplasms can present as nodular masses and early sarcomas or carcinomas may palpate as discrete, encapsulated masses that grow rapidly. Angiosarcomas can appear as one or more erythematous nodules in the skin or soft tissues that grow rapidly, often with necrosis and thrombosis, and are typically red to black on cut section. Cytologic evaluation should be performed to exclude mast cell tumors before surgery to allow for appropriate planning of wide margins. Histopathology is generally required to establish a definitive diagnosis.
Chapter: Dermatology
Source: The Merck Veterinary Manual, 11th Edition (Page 366)