TL;DR: Mammary tumors are common breast growths in female dogs that require a veterinary exam within 1-2 days. Seek immediate emergency care if the lump is bleeding, growing rapidly, or if your dog has difficulty breathing.
What are mammary tumors in dogs and how common are they?
Mammary tumors are growths that develop within the breast tissue of female dogs. These tumors are highly common in unspayed females because their breast tissue is regularly stimulated by hormones like estrogen and progesterone during heat cycles. Statistics show that approximately 50% of these tumors are benign, while the other 50% are malignant (cancerous) and have the potential to spread to the lungs or lymph nodes.
Should I take my dog to the emergency vet for a mammary lump?
Urgency Level: Medium. Finding a lump in your dog's mammary chain is not typically a same-hour emergency, but it does require a veterinary examination within 1-2 days. You should seek immediate care if:
- The lump is rapidly growing or bleeding.
- Your dog is showing signs of respiratory distress.
- You are prepared for early surgical intervention, which is often curative for benign cases and the most effective treatment for malignant ones.
How can taking a photo of my dog's tumor help with triage?
Taking a clear, well-lit photo of the affected area can be incredibly helpful for your veterinary team for the following reasons:
- A photo allows a professional to assess the size, location, and appearance of the mass, including whether the skin is ulcerated or inflamed.
- Visual data helps the clinic prioritize your appointment based on severity.
- The image provides a baseline to track if the tumor is changing shape or size over time.
Clinical Context (Merck Veterinary Manual)
Mammary tumors in dogs are most frequent in intact bitches and extremely rare in males. Ovariectomy before the first estrus reduces the risk of mammary neoplasia to 0.5% of the risk in intact bitches, and after one estrus to 8%. Bitches neutered after maturity are generally considered to have the same risk as intact bitches, however, spaying less than 2 years before tumor excision may increase survival. Tumors appear as single or multiple nodules (1-25 cm) in one or more glands, and are surgically treated with options ranging from lumpectomy to radical mastectomy, although more involved procedures have not prolonged survival in dogs. Histopathology is important in defining treatment and prognosis, and adjuvant chemotherapy may be considered to combat micrometastatic disease.
Chapter: Oncology, Surgery
Source: The Merck Veterinary Manual, 11th Edition (Page 1404)