Here's why:
* Full-blooded refers to a dog that has only ancestors of the same breed. This means they are purebred.
* Purebred dogs are typically bred from two parents of the same breed, where both parents have established lineages within that breed.
Since you have two male boxer dogs breeding with one female, the resulting puppies will have two different fathers. This breaks the purebred lineage, meaning the puppies would be considered mixed breed or crossbred, even if all three dogs are boxers.
While the puppies will still have boxer traits, they won't be considered full-blooded or purebred boxers due to the multiple fathers.