While different breeds of dogs have different numbers of bones in their tails, the average number of bones in a dog's skeleton, taking into account tail variation, is 319, according to Pet Education. Bones grow throughout a dog's lifetime, which means that all dogs are born with the same number of bones they will keep the rest of their lives.
Bones in a dog are made up of various minerals, but are primarily phosphorus and calcium. The bones have their own blood supply and have the primary purpose of protecting vital organs and providing structure, notes Pet Education. The skeleton of an animal is the framework of how the animal will look, and all muscles, tendons and ligaments work around the skeleton to move bones around joints. For the most part, all dogs have similarly configured skeletons, just with different proportions. For example, short dogs have smaller bones in their legs and tall dogs have the same number of bones, but the bones may be longer.
The only difference in the number of bones a dog may have is in the length of its tail. Because there are bones that run through the tail, dog species with longer tails have a higher number of bones than those with short tails.