I dunno. It could still be a prolapse, but it looks more like an injury/irritation to the outer edge of the cloaca to me? Not the actual hemipene or intestine. Maybe he had recently passed a rather large urate stone or fecal?
I've thankfully never had snake prolapse before, only a couple geckos so I could be wrong~ Though it does look a bit like the irritation a snake I have with a burn had gotten after passing the first feces after the injury. BCR sounds like he has seen this before tho, so they're probably the best bet.
I would still treat it like a prolapse that way the tissue doesn't stay inflamed. Obviously keep an eye on it as mentioned above, if it was a healing prolapse, he may be prone to it again.
Reply With Quote