It should definitely be marked as NSFW, but different cultures look VERY differently to death, and to pet death as well. It should be marked for that reason, but otherwise the ones I've seen are very similar to a human open casket funeral / viewing.

People go to these places to show it because people with the same kind of pets can often relate better than other people. And if it gets upvotes I doubt many people there find it as objectionable.