My old dog had this, it was a fluid filled cyst in his case, the vet drew fluid off it periodically if it got too big, usually at vaccination time. It didn't bother my dog at all and I seem to remember it did stop refilling.
Hi, did you find out what it was and did it clear up?
My boy has suddenly got a very big (palm/handful) sized lump over his shoulders/base of his neck this morning. I thought he had a slight dip in his spine the other day and made a mental note to mention it to the vet at his next appointment, but am now thinking it could have been swelling in front making it appear that way.
He did have swelling around his microchip as a pup, after a particularly rambunctious play session with our older dog, but that settled on it's own within 48 hours. This is much lower down on the shoulder/withers seems to be getting bigger as the day goes on - which does suggest perhaps fluid accumulating - but I can't get him in to the vets until first thing tomorrow morning, as they have no appointments.
I'm wondering if his microchip is travelling and causing an immune reaction - is that even possible?