Several Lumps That Don't Bother an 8-Year-Old Dog
by Mike
(Florida)
Many lumps that don't bother a dog are benign, such as lipomas, but it isn't possible to tell by feel alone.
A good rule from veterinary oncologists is "see something, do something": any lump the size of a pea (1 cm) or larger that has been there for a month should have a needle aspirate or biopsy. Your vet can check them quickly with a needle and map them so you can watch for changes.
This is general information, not a diagnosis. Please follow your own vet's advice.