I am woundering why some breeds always have their tails cropped, while other breeds they leave the long.

Some dogs like Dobermans, because of the length and girth of their tails, they can break easier. So to save them from a "potential" breakage, and pain, it is better to have them docked.That is what the vet told me and my grandpa a few years back.

Cropping dogs tails is manly for two reasons, first manly for looks. Dog breeds that are known for it, usally have it done for looks. Other wise, it could be to prevent happy tail, dogs with happy tail can hit it on things which can cause bleeding. Personaly, unless it's a medical reason I would say don't do it.

If you own a pet that normally has a tail docked, you are certainly free to leave it if you like it.It is different for us that show and breed dogs. We must follow strict ACK guidelines on breed standard.. If the breed standard calls for a docked tail, then you have to have it to show your dog.This is the way it's been for years and years and things don't change very fast.On an upbeat note, dog shows in Europe are starting to get away from tail and ear docking. Maybe someday that will happen too. But don't worry about pain. Everything is done a certain way at a certain age to minimize discomfort. Hope this answered your question!!