Canine Anatomy

Over the centuries, humans have developed hundreds of different dog breeds. Some are tiny, some are huge, some have little heads with big ears and some have big heads with little ears.

The skeletal and muscular systems of the different dog breeds, while similar, do reflect refinements that characterize the breed. For example, a dog with a long neck may have longer vocal cords and thus a deeper bark, while a shorter neck and shorter vocal cords produces a higher-pitched bark.

The anatomy of the dog reflects its history as an omnivorous animal, able to derive nutrition from a variety of sources. Its huge teeth illustrate its close relationship to the wolf and remind us of its carnivorous ancestry.

From a nutritional and metabolic perspective, however, the dog also eats and thrives on nutrients from plant sources as well as meat sources.

The Skeleton

A dog”s skeleton is formed so the dog can run fast, hunt and chase. For example, a dog”s shoulder blades are not tightly connected to its skeleton, so the dog has potential for greater motion and flexibility.

Of course, not all dogs have the exact same type of bones. Since humans have been breeding dogs for centuries, bones may vary in length and thickness, depending on the breed.

The Various Head Shapes

The two basic skull shapes for dogs are a narrow head and long face like the borzoi, or a short head and wider face, like the pug. Of course, between those extremes lie an enormous number of variations.

The Teeth

Of a dog”s 42 teeth, six pairs are incisors and two pairs are canine teeth. The remaining teeth are molars. Traditionally, the most important teeth for the dog were the incisors and the canines, because they helped the dog rip and bite his food. With domestication and prepared diets, a full set of functioning teeth is no longer a life and death issue for most pet dogs.

The Claws

A dog”s claws are fairly strong. They help the dog to run, maneuver and dig and offer some protection. They also help to provide stability to the feet. However, a dog”s claws just don”t seem to be a particularly defining part of their anatomy, as they might be to a cat who needs claws to climb away from danger.

Unlike cats” claws, which can be retracted and are very sharp, a dog”s claws are more like humans” fingernails and cannot be retracted.

The smaller claws that are located on the inside of the legs above the other claws are called dewclaws. They actually represent the first digit or toe on a dog, located a short distance up the leg on the inside surface, and are not used for walking. Although they may have been functional in the past, dewclaws no longer serve a purpose for the dog. Some dogs may be born with front dewclaws only, or any combinations of front and back.

Dewclaws are prone to getting snagged and ripped, so many breeders prefer to have them removed when the puppies are just days old. If you”re not showing your dog, discuss dewclaw removal with your veterinarian during your first appointment.

The Muscles

Most dogs are built for endurance, not speed, and their muscles reflect this. Collectively, the muscles are the largest organ system in the dog”s body.

Although the dog”s muscles are not quite as well-built as those of his close cousin, the wolf, some breeds have been bred to run faster than thirty miles an hour.

The Tongue

The tongue is one of the most important muscles in the dog”s body. It serves several purposes:

  • helping food get to the throat
  • cleaning the coat
  • panting
  • licking owners and ice cream cones.

Why Does a Dog Pant?

A dog”s panting is similar in function to a human sweating. Panting helps lower the dog”s body temperature by the evaporative action of moving cool air over the tongue. The result is a cooler dogprovided the air is cooler than the dog. Dogs left in hot, parked cars with poor ventilation derive no benefit from panting because the air is warmer than the dog.

If you see your dog panting heavily, make sure she has plenty of fresh air and clean, cool water in her bowl.