Some colorations are influenced by temperature. For example, Siamese cats have dark points because their extremities are colder than the rest of their body. When my Siamese went in for her spay her fur grew back darker where they shaved her leg because the skin was exposed to the air and got colder. Your bun’s fur seems to be doing the opposite, but I guess it could still be the same thing? My Siamese eventually shed the dark fur and it grew back in her normal color.

Would be interesting to see a picture 🙂

Maybe the hairs in that spot turned white due to some local damage to the skin and the hair follicles from the IV.

It may also be a coincidence that it happens to be where the IV had been? One of my rabbits has a white stripe across his left shoulder blade. As he grew, the solid stripe became longer and also ended up “breaking apart”, i.e. black fur started growing within the stripe and making it less solid. Perhaps she was always meant to have that grow in as a part of her fully matured coloration.

I’m not sure, the people above me have better ideas. But in the photo the little mark looks like a sideways heart which is cute, but I hope it’s not anything to worry about!

I’m sure its absolutely nothing to worry about! Whether it stays white or the color comes back in. Humans can get white hairs on a patch of their scalp after a local injury, but it isn’t problematic in any other way than at the most cosmetically.

I think it can happen with trauma, it affects the hair follicle ability to produce color, but it should be no danger to the Bun. I have seen it in cats and even humans. Siamese cats definitely, but I had a friend who had an accident where she needed some stitches on her head, when the hair grew back most was normal but she then had a little white streak. I just noticed @Bam had just said the same thing.  Sorry to be repetitive, should have read ALL the comments!

I do agree with Moonlight it does look like a little heart! <3