That looks like something (fur, pee, poo, etc.) matted and stuck to his tail.

You may have to burrito him with his rear sticking out. You can carefully cut the mat off. Just be careful not to cut his tail! His bottom looks a bit dirty, which can be a sign of other problems. Unless he is making a habit of sitting in pee… some bunnies do that.

Yes, it will probably need to be examined closer and be a 2 person job.  A towel could help keep him secure and hopefully calmer. 

It’s really odd. It does appear like a matt of fur.. but his tail otherwise looks really good. It doesn’t appear soiled. His feet and inside of legs look good also.  Is the underside of tail more soiled? 
There is a corresponding area to the left that is a little yellowed. I wonder if there was a matt between this area and the tail and it’s now come free? 
Im also wondering what this is? Is that just the photo or is there a long piece of something coming out of the matt?

The pink you can see is a healthy looking testicle. There should be another nearby. They can draw them up though so it’s not always easy to see them. 

It looks like he got pee on his tail an it matted. Why would your vet tell you not to neuter him? All rabbits should be spayed/neutered even if you don’t have another rabbit or plan on not getting another one. Do you plan on neutering? Spaying/neutering helps expand life spans and reduces hormones as well as helps prevents cancer.

I’d also suggest finding another Vet I wouldn’t trust a vet that believes a rabbit shouldn’t be spayed/neutered if you don’t own another rabbit. I also hope I’m not being rude that’s not what I attend to do.

Posted By Thumper_LittlePeanut on 12/24/2018 4:46 PM
It looks like he got pee on his tail an it matted. Why would your vet tell you not to neuter him? All rabbits should be spayed/neutered even if you don’t have another rabbit or plan on not getting another one. Do you plan on neutering? Spaying/neutering helps expand life spans and reduces hormones as well as helps prevents cancer.

It’s not unusual for people to opt not to desex a male rabbit if he is a single bun. The cancer risk is significant for female rabbits, not males. There is a hormonal phase, as with any rabbit as they mature, but the hormones level out some and a single intact male rabbit can develop good litter habits and be a pleasant companion. There may be occasions when there’s a slight hormone surge and temporary increase in hormonal behaviours. They also might mount items or even try mount other pets.

I personally would have a male neutered, even if a single rabbit, but as I said, it’s not unusual for people to opt out or for vets to say it’s not necessary if owners don’t want to have it done.