Had to post this in the 2 mins I've got before work so sorry if it's a bit brief.

My son noticed late last night that Sash has got a red lump at the corner of her mouth, it's a bit wet and looks sore, she flinched when I touched it.  Its quite hard to the touch.  She had her booster on Monday.

Any ideas?

Thanks in advance

Abcess, wet eczema, grass seed?  Could be anything really.  If it is not improving by this evening I would have a vet look at it.

Thanks Isabel.  I would say it's definitely not eczema - it's quite a pronounced lump. I was wondering if it might be a sting?

Yes, lots of insects about and they just don't seem to learn to leave them alone do they?

She's never been stung before. Think I'll just take her to the vet after work.  It's just not my week, Jack had another fit this morning (despite being on his epilepsy meds) and my eldest son is at home in bed with a virus!!

Just got back from the vets.  It's a histocytoma and it's a bit infected from where she's been rubbing it.  So it's antibiotics for a while and (oh joy) an elizabethan collar.  If it doesn't go down, it'll have to be removed and tested.  Apparently, sometimes mast cell tumours are mistaken for histocytomas!

Anyone have any experience of these?

Yes, one of my dogs had a histocytoma on her leg, it was flat and about the size of a 5p piece (she's a Cairn, so on her leg this was not a small lump) - next to a joint.

  brought her to the vet and he recommended surgery because of its location - any bigger and they would need to take out too much tissue.  At that time, of course, it was not clear what it was - as your vet said it is really impossible to tell without a biopsy.  Dropped her off for surgery and the vet called later in the day to say he was not going to operate because he thought the lump was smaller than he'd seen it earlier in the week.    (I have a good vet!)  Got some cream to put on it a couple of times a day and within 2 or 3 weeks it was gone.