It was a sunny December morning. Charlie flopped down in front of the fire after a good romp at the park. As her owner stroked the right side of Charlie’s belly, she felt a bump. The bump hadn’t been there earlier in the day, and while Charlie paid it no mind, a phone call was promptly placed to our hospital to book an appointment. During that visit, a growth was found underneath the skin on Charlie’s flank – it was small and well defined.
“What do you think it is Doctor?” Charlie’s dad asked.
“I can’t say for sure without a biopsy. Could be a benign fatty lump. It is right next to a nipple, so it could be a mammary tumor – these are usually benign in a dog that was spayed before the first heat. A mast cell tumor is always a consideration with any lump. Mast cell tumors are cancerous, although those that are low grade can be cured with surgery.” I said.
To put it plainly, mast cell tumors are nasty buggers. Their red and itchy appearance when growing from the surface of the skin, is fairly characteristic and prompts us to take quick action. But when growing underneath the skin, they can feel very much like a fatty lump (aka lipoma). Mast cell tumors tend to send cancer cells to “stake out” the neighbourhood tissue. This means that they often spread locally, and are larger than they appear to the naked eye.
It turned out that Charlie did have a mast cell tumor. But, thanks to her owner’s careful observations and quick decision making, surgery to remove the mass was successful.
Whenever I’m asked what a growth is, be it on or under the skin, I wish I could be 100% certain in my answer. But I can’t. No one can. Only a biopsy, either needle or surgical, can provide a more definitive answer. So while many lumps and bumps are harmless, it’s important to talk with your veterinarian any time one is found on your pet.