My friends dog recently got a tennis ball size lump on his neck out of the blue. It came on really fast, like one day it wasn't there the next it was. It's a Cockerspaniel and the lump is about 2/3 the size of a tennis ball. She took him to the vet and they did some blood work and said he had an infection but had no idea what it was. It was rock hard so he couldn't lance it open. The dog seemed to be in no pain and the lump was rock hard. Now the lump is still there but has gotten a lot softer, although now it's causing him pain if you touch it. He wasn't eating anything on Tuesday but now, Wed. he's eating and playing although it's still painful. Every day it's getting softer and softer.
My question is, does anyone have any idea what it could have been? Anyone ever seen this? My guess was a snake bite but who knows.