How do you tame a big dog?

Do you mean train or tame?

If you have a wild or vicious dog don’t try to tame it. I know this sounds cruel but if you have a viscious dog you will probably have to have it put down. There are dogs that are so agressive that they will never view you as alpha and will be untrainable. About the only occupation suitable for this kind of animal is as a junkyard dog.

If you have an animal that needs training that is a different story. The classic method is with rewards rather than punishment. Always make your dog mind; if you call your dog and (s)he doesn’t come phisically get your dog and bring it where you were calling it from. If you let your dog get away with not minding it will view every command as optional. Make your dog view you as alpha by making your dog earn everything. Make your dog perform a trick (as simple as sitting is good enough) before every treat and before you show any affection. Unless a reward don’t let your dog on your furniture. A dog that sleeps and sits the same place you do is more likely to view you as an equal than a master.

Older dogs are still trainable but if you don’t have the knowledge or experience it may be worth looking at a local dog-trainer or obedience school.

If you do mean “tame” however, you need to look at what the issue is, if the dog is wild, or ferral, they will be much harder to domesticate and if they are indeed vicious they are unlikely to ever be domesticated enough to be safe in a family envrionment.

Any concerns should be discussed with your vetinarian and they will be able to provide you with local information on trainers or schools