...as a business? I raise, train, show and sell Golden Retrievers. I deduct their food, vet bills, travel, license etc. How do I deduct the cost of a puppy I purchased who will be used in breeding when it is older?

You could depreciate the cost of the dog over the period that it is likely to be used for breeding purposes. In the alternative, you may be able to deduct the cost of the dog in a single year as a Section 179 expense (check the depreciation tax form).