Q. My old dog has a few little lumps. The first couple of times they turned up, I took him to the vet, but she said they weren’t anything to worry about, that they were “fatty.” When are they something to worry about?

A. The fatty tumors known as lipomas are common in dogs, especially older ones. They’re generally round, can be pushed around with the skin they’re in, and have margins that can be easily defined by the fingertips. They feel as if they’re made of the same gel material as those blue ice packs before they're frozen.

You can’t tell for certain that any lump or bump is “benign” by looking at it and neither can your veterinarian. Your veterinarian may suggest a needle biopsy, which entails drawing cells out of the mass and taking a look at them under a microscope.

If the mass is determined to be a lipoma, it probably just needs to be watched for growth or changes in appearance. If its size or placement causes your dog discomfort, though, it will likely need to be removed. If a lump isn’t a lipoma, your veterinarian will likely suggest further diagnostics to determine what she’s dealing with and help her decide the best course of treatment.

Some masses, such as sebaceous cysts (plugged oil glands), are fairly easy to treat from a medical perspective, while other lumps truly are bad news.

To sort the benign from the bad actors, you need to be aware of the lumps and bumps on your pet and have your veterinarian take a look regularly — immediately if a lump is growing rapidly or otherwise changing in appearance or feel. Even when the mass is bad news, the earlier the problem is detected the better the treatment options — and the better the chance of your dog’s surviving what may be cancer.

In other words, when in doubt, have your veterinarian check it out.