Hmmm, it’s hard to say, but it looks like it could be an abscess since there is some swelling. I would have it looked at by her vet.

It does look like there is a scratch or nick on the top. It’s good the area isn’t a raised lump.

I suppose she might have been vigorous cleaning there after her spay. They put an ointment on the eyes to stop them drying out during the surgery.

Is she a single bun? Or is there another that may have groomed her too much?

I had one bun with a dental abscess, and he showed the signs of dental problems (not wanting to eat hay, drinking lots of water). The abscess kind of popped up overnight, once we already knew he was having dental issues. Buns show symptoms very differently though, and I imagine it might be complicated given her spay recovery. If that turns out to be the case, it’s best to pursue the most aggressive treatment possible as soon as possible, as they can be stubborn. The vet would likely be able to feel it. They would also examine her teeth to see if any of them appear to be a problem.

The timing is strange, but I wonder if maybe her system was a bit weak due to the spay, and that caused it to grow quickly? If she’s eating normally and pooping normally, I would probably call the vet to ask, but I imagine they will say monitoring or a day or two would be OK.

The usual treatment involves cleaning it out surgically (and figuring out what needs to be done with the teeth that are the source), and treating with injections of antibiotics. In rabbits, the pus inside the abscess capsule is very thick, so they do not drain on their own (like a cat’s would, for example).