Soft Lump On Puppy's Head. Fewer than half of lumps and bumps you find on a dog are malignant, or cancerous. Lumps are a very common occurrence on pets and is a good reason for us to examine our pets regularly.

Given your history and description, it sounds like it may be a swelling due to a bump on the head. Still, they can look the same from the outside, so it’s. The concern is that a small bump on a dog could be cancer.