TL;DR: Most fluid-filled lumps on dogs are non-emergency cysts or seromas, but they should be monitored for signs of infection like heat or pain. Take photos of the growth to help your veterinarian track any changes and determine if urgent diagnostic testing is needed.
What are the common causes of a fluid-filled lump on my dog?
Finding a soft, squishy, or movable lump under your dog's skin can be concerning. These are typically pockets of fluid trapped beneath the surface, such as sebaceous cysts, seromas, or hematomas. While they may feel unusual, many of these growths are benign collections of fluid rather than solid tumors.
When is a fluid-filled lump on my dog considered a medical emergency?
- The urgency for a fluid-filled lump is generally low if your dog is acting normally, eating, drinking, and playing.
- Schedule a routine appointment with your veterinarian for a physical examination.
- Seek immediate care if the lump is hot to the touch, oozing foul-smelling discharge, or causing significant pain.
- These symptoms often indicate an abscess or infection that needs prompt treatment.
How can taking a photo of the lump help with my dog's triage?
- A clear photo allows your veterinary team to assess the exact location, size, and color of the growth.
- Visual records serve as a baseline to identify if the lump grows or changes shape over time.
- This evidence helps your vet determine how aggressive the growth is and if an urgent biopsy or fine-needle aspirate is necessary.
Clinical Context (Merck Veterinary Manual)
Fluid-filled lumps under a dog's skin can be caused by hygromas, lipomas, or fibromas. Hygromas, often found over pressure points like the olecranon, may contain clear, yellow, or red fluid and can develop into ulcerations, infections, abscesses, granulomas, or fistulas if longstanding. Lipomas typically appear as soft, discrete, occasionally pedunculated, and freely movable nodular masses, most commonly on the trunk and proximal limbs of older, obese female dogs, with Doberman Pinschers, Labrador Retrievers, and Miniature Schnauzers being at higher risk. Fibromas, more common in older dogs such as Doberman Pinschers, Boxers, and Golden Retrievers, appear as discrete, raised, often hairless nodules in the dermis or subcutaneous fat and can be either firm or soft; complete excision is recommended if they change in appearance or grow large.
Chapter: Dermatology
Source: The Merck Veterinary Manual, 11th Edition (Page 973)