Nail Clipping

If your dogs are anything like mine, they absolutely hate it when their paws are messed with and, heaven forbid, clipped. I have a lab that is particularly bad with nail trimming, and will resort to aggressive behavior if we don't do it right. But there are ways to get your dog used to nail trimming.
Here is a good article that describes in detail how you can work with difficult dogs when it comes to nail trimming:

http://www.canismajor.com/dog/nailsv.html

Summarized, it is important to have the right holding technique with your dog so that your dog is secure and cannot get up or struggle, but he doesn't feel smothered or overwhelmed. It helps to have two people available when you first start clipping your dogs nails, especially if it is a big dog. You must be firm when correcting your dog, and you must correct every time he puts up a struggle or tries to bite. Consistency and timing is key, as always, with dog training.
Have some extra tasty treats with you to distract your dog from the ordeal, and soon he may even start enjoying himself. I have found that frozen peanut butter on a spoon will keep a dog busy enough not to need restraining, but it all depends on the dog.
Don't give into your dog if he starts to bite or make a scene. A muzzle may be necessary in severe cases, but you must show your dog that he will not get his way from biting. Correct him when he is not cooperating, and reward him for holding still or every time you clip a nail. Make it a fun and positive experience for your dog, not one he will dread.