The dog (Canis lupus familiaris) presents a very significant morphological diversity, which complicates its study. The anatomy of the dog should be studied according to the breed but this would be an endless task, moreover it is not only the breeds, but their crosses. Dog bones vary between breeds, with some having more bones than others. The same goes for muscles.
In this article on our site we will talk about the dog's anatomy, we will see the different morphologies, what bones they have and much more.
Canine anatomy
The anatomy of the dog is very broad due to the diversity of breeds that exist. The different breeds of dogs not only differ from each other in size, but also in the shape of many parts of the body. One of them, perhaps the most significant, is the head. Mainly, we find three different head types:
- Dolichocephalic: dolichocephalic dogs have heads longer than wideThe skull and snout are elongated, the eyes occupy a lateral position, which makes it difficult for these animals to see well bifocally. The breeds that present this type of skulls are greyhounds or sighthounds. They also usually have a little pronounced stop. The stop is the area of the dog's face where the snout meets the forehead and, in these dogs, it is usually smooth, not very marked.
- Brachycephalic: the head of brachycephalic dogs is characterized by being as long as it is wide In addition, they have a very marked stop. Due to their anatomy, they usually have many respiratory problems. The breeds that present this anatomy are the boxer, bulldogs, Pekinese, etc.
- Mesocephalic: Mesocephalic dogs have a head with intermediate featuresbetween the two previous types. They may or may not have a very marked stop. Pointers, beagles and fox terriers are some of the breeds that have this type of head.
On the head we find the snout, which can be long, short, wide or narrow. The muzzle borders the forehead at the stop, which also has a wide variety of shapes, very convex in brachycephalic dogs or even fully concave in breeds such as the Bedlington terrier. The muzzle ends at the nose, which is the end of the dog's nose. This area of the body is covered by a special skin, very rough and, although they have a similar shape in all of them, it can be placed more or less low.
Continuing with canine anatomy, all dogs have the same number and type of teeth, but the bite varies. Some dogs close their mouths by placing their teeth in a clamp, so that their incisors rub their edges against each other. Others have a scissor type of bite, with the inner edge of the upper incisors rubbing against the outer edge of the lower incisors. In addition, there are dogs with prognathism, where the lower jaw protrudes from the upper jaw, very typical of breeds such as boxers or bulldogs. Finally, when the upper incisors protrude over the lower ones, we speak of enognatism, and it is always a defect in the dog, not linked to the breed.
Like other regions of the dog's anatomy, eyes and ears also differ greatly between breeds. We can find pointed, rounded, erect, drooping ears, etc. The eyes can have different shapes, more rounded, oval, triangular. In addition, on the face they can be placed more or less centrally, be in a deeper position or, on the contrary, bulge.
Dogs also have tail This extremity is cut on many occasions by dog breeders themselves for aesthetic reasons, preventing the animal can communicate correctly with other dogs. Dogs' tails come in various shapes and lengths. Sometimes, they are implanted in higher areas of the back and other times lower. They can be twisted, twisted like a curl, straight or slightly curved.
The dog's body is made up of the trunk and abdomen. These can vary by the shape of the spine, which we will see in more detail in the next section. The withers of the dog is where we usually measure its height, being the insertion point of the neck with the thorax, where the scapulae are located. Both the withers and the croup (end of the back) can have different heights, giving rise to dogs having different back shapes depending on the breed
As you will see, the anatomy of the dog is really varied. This is due to the anthropic selection of the crossbreeds, creating very diverse breeds, causing changes in the natural anatomy and, on many occasions, giving rise to problems incompatible with life, such as, for example, the total tracheal collapse of breeds " mini".
Dog Skeleton
The skeleton of the dog, as in the rest of vertebrate animals, has a function of supporting the body and protecting the internal organs. We can divide the canine skeleton into three parts:
- Axil skeleton: skull, vertebral column, ribs and sternum.
- Appendicular skeleton: limb bones.
- Splanchnic or visceral skeleton: these are bones developed within viscera, such as the bone of the penis.
The skull of dogs has many ridges, bumps, and processes between the various junctions of the skull bones. This makes it easier for the dog's head muscles to insert.
The dog's vertebral column is divided into cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacral vertebrae and coccygeal vertebrae. The cervical vertebrae are seven, the fact that there are dogs with a more or less long neck does not imply that they have more or less cervical vertebrae, only that they will be more long or short, since all dogs have seven vertebrae in the neck. Dogs have thirteen thoracic vertebrae which are characterized by a very prominent spinal process or spine. The first dorsal vertebra determines the region of the withers, where the height of the dog is measured. The seven lumbar vertebrae form the base of the loin. There are three sacral vertebrae and they are fused over the hips. They are the base of the rump and where the tail vertebrae will be inserted or coccygeal vertebrae The number of vertebrae in this region varies greatly from breed to breed but, usually between twenty and twenty-three.
Continuing with the canine anatomy, we now turn to the extremities. The front legs of dogs or forelimbs are made up of the following bones, from closest to the body to furthest away: scapula, humerus, radius, ulna, carpus, metacarpus and phalanges. The hind legs or hindmembers have these bones: coxal, femur, tibia, fibula, tarsus, metatarsus and phalanges.
Dogs have thirteen pairs of ribs all articulated with the dorsal vertebrae. Only 9 of them articulate with the sternum, the remaining four are linked together by elastic tissue. The ribs can have different morphologies depending on the breed of dog, so we find 4 different types:
- High-arching ribs: These are ribs with a smooth shape, well separated from the spine and joining the sternum without creating sharp vertices.
- Barrel-shaped ribs: The ribs are very arched and separated from the body.
- Flat Ribs: They are well sprung but drop abruptly and parallel.
- Keel ribs: they have a good curvature until, at a certain point, they join the sternum abruptly, which gives a keeled appearance like in birds.
The penile bone or staff is very common among mammals. It maintains the erection during intercourse instead of doing it through the blood and cavernous tissue as in humans.
How many bones does a dog have?
Do you know how many bones dogs have? Again, to find the answer we must look at the different races. In general, dogs have 321 bones, depending on whether or not they have vestigial fingers, like mastiffs, or if they have a more or less long tail. For example, Pembroke Corgis are born without a tail, so they have fewer bones, or Croatian Sheepdogs or Spanish Bretons can also be born without a tail. In all cases it is due to a genetic mutation that is always negative, since the tail is essential for communication between canids. In the wild, away from human protection, a dog without a tail would have serious problems communicating properly. Check out this article to learn more about it: "Why Dogs Wag Their Tails."
Dog muscles
Within the dog's anatomy we find the muscular system, which is made up of muscles, tendons and ligaments. A dog can have between 200 and more than 400 muscles, here we return again to the difference between breeds. As a curious fact, some breeds have more than 50 muscles in their ears alone.
Most of the muscles of dogs are concentrated in the front part, as we can see in the image, which It is where the dog's strength lies. Many of the muscles, especially those of the neck and chest, are directed towards the sternum, and this gives power to run and hunt.
A very important muscle is the masseter, located on the head, in the cheek area. This muscle is highly developed in breeds such as the American Staffordshire Terrier, dogs with a very powerful bite.
The shape and size of a dog's muscles will be defined by its breed, with some muscles being more developed in certain breeds.
Dog Organs
The internal anatomy of dogs, as a mammal, is very similar to the anatomy of other carnivorous mammals, such as cats. Dogs have a developed brain, composed of a cerebrum that performs functions such as learning, the cerebellum for coordination, and a medulla oblongata that is responsible for autonomous functions such as breathing or heartbeat. All followed by the spinal cord, protected by the vertebral column.
The circulatory system of the dog is formed by the heart, located in the thoracic cavity slightly to the left, as in the human being, veins, arteries and capillaries that distribute blood throughout the body.
Dogs breathe through their lungs. Your respiratory system is made up of the larynx, where we find the vocal cords, trachea, bronchial tubes, and lungs.
Dogs are facultative carnivores and, therefore, their digestive system is designed for meat consumption. It is made up of the digestive tract, which is divided into the esophagus, stomach, small intestine, and large intestine, and associated glands, such as the liver, pancreas, and gallbladder.
For the excretion and cleaning of blood, dogs have two kidneys, one located higher than the other, and a bladder that collects urine and then expels it.
The reproductive system of dogs consists of the testicles, prostate, seminal vesicles, and penis. The reproductive system of female dogs is made up, from the outside in, by the vulva, the clitoris, the vestibule, the vagina, the cervix or neck of the uterus, the uterus which is divided into two uterine horns and the ovaries.
Finally, dogs also have a set of glands that exclusively produce hormones to regulate the body. These glands are: pituitary, hypophysis, thyroid, parathyroid, thymus, and adrenal glands. Although other organs contribute to hormonal regulation, such as the ovaries, testicles, liver, kidneys or pancreas.
Now that you know all the details about the anatomy of dogs, don't miss this other article with curious facts: "Curiosities about dogs".
