Your dog’s body is full of complex anatomy, with all its parts working in concert to keep your dog healthy and mobile. You don’t have to be an anatomy expert to be a good dog parent, but it is helpful to have a basic understanding of how your dog’s body is put together. In this article, we’ll focus on dog leg anatomy.
A dog’s legs play a major role in bearing body weight and providing stability, support, and locomotion. They function similarly to a person’s arms and legs.
The anatomy that supports all these functions is complicated. Don’t worry—you don’t have to memorize every anatomical feature of your dog’s legs. We’ll help you understand basic dog leg anatomy, describe common leg injuries, and provide tips to keep your dog’s legs healthy and in good working condition.
Parts of a Dog Leg: A Quick Overview
A dog has two front legs and two hind legs, which consist of muscles, bones, joints, ligaments, tendons, blood vessels, and nerves. This article will focus on muscles, bones, joints, ligaments, and tendons that make up dog leg anatomy.
Let’s define a few of these terms:
Joints: The connection point between two bones. There are several types of joints, according to what motion they facilitate (ball-and-socket, hinge, etc).
Ligaments: Tough cords of connective tissue that support and stabilize joints.
Tendons: Tough bands of connective tissue that connect muscle to bone.
Do Dogs Have Knees?
Yes, dogs have knees (also called the stifle), which are located on their hindlimbs below the thigh bone. The knee is a joint (stifle joint) with numerous components that we’ll describe later in the article. It is susceptible to several types of injuries.
Do Dogs Have Elbows?
Yes, dogs have elbows. A dog’s elbows are located on their front legs. The elbow is a joint that connects the top arm bone to the forearm bones.
Do Dogs Have Shoulders?
Yes, dogs have shoulders. However, unlike in humans, in which the shoulder bone connects to the collarbone, the shoulder bone in dogs does not connect to another bone. This disconnection allows dogs to take long strides when they run.
Do Dogs Have Ankles?
Yes, dogs have ankles. In dogs, the ankle is called the hock. The hock sits at the bottom end of the shin bone in the back legs and serves as the connection point between the shin and paw bones. It makes a sharp angle and points upward.
Dog Hind Leg Anatomy
The back leg anatomy will be the same regardless of your dog’s breed. The hind legs carry about 1/3 of a dog’s body weight.
The main variation will be the size of the different parts. For example, a Chihuahua will have much shorter hind leg bones than a Great Dane.
We’ll break down the anatomy according to component parts.
Bones
The major bones in a dog’s hind legs are listed below, from the top of the leg to the paw:
- Femur: Thigh bone; connects to the hip bone via the hip joint
- Knee: Stifle; Sits below the femur
- Patella: Kneecap
- Tibia: Shinbone; main bone in lower leg
- Fibula: Shinbone; small bone beside the tibia
- Ankle: Hock; connects shin and paw bones
- Paw bones: Tarsals and metatarsals; equivalent to human foot bones
Joints
The main hindlimb joints are the hip, knee, and ankle joints.
The hip joint connects the top of the femur to the hips. It is a ball-and-socket joint that allows for flexing and extending the legs.
The knee joint is a hinge joint that connects the femur to the tibia and fibula and facilitates flexion and extension of the lower leg. It is also categorized as a synovial joint because it contains synovial fluid to reduce bone friction. Several ligaments stabilize the knee joint.
The ankle joint connects the shin and paw bones. It allows for flexion, extension, and rotation. Numerous ligaments support and stabilize a dog’s ankle joint.
Ligaments
The most important ligaments to remember are those in the knee joint: caudal and cranial cruciate ligaments and medial and lateral collateral ligaments.
These ligaments surround the knee joint, providing critical stability and support. The cranial cruciate ligament (equivalent to the anterior cruciate ligament in a human knee) is a common source of leg injury in dogs.
Tendons
The Achilles tendon is the main tendon to remember in a dog’s hind legs. This tendon is not a single tendon — it is a complex of three tendons working together to stabilize the lower back leg, extend the ankle, and flex the paws. A dog’s Achilles tendon is prone to injury.
Muscles
The list of hindlimb muscles in dogs will make your eyes glaze over, so we’ll keep it simple. The primary muscles to know in the hindlimb are the quadriceps (thigh muscles), hamstrings, and gastrocnemius (calf muscle).
Dog Front Leg Anatomy
A dog’s front legs bear about 2/3 of a dog’s total body weight. Like the back legs, they have complex anatomy.
Bones
Here are the bones in a dog’s front legs:
- Scapula: Shoulder bone
- Humerus: Upper arm bone
- Radius and ulna: Forearm bones
- Carpal bones: Wrist bones
- Metacarpal bones: Connect the wrist to the phalanges (toes)
- Phalanges: Toe bones
Joints
The major joints to remember in a dog’s front leg are the shoulder, elbow, and wrist (carpal) joints.
The shoulder joint is a ball-and-socket joint, like the hip joint. It joins the top of the humerus to the scapula and is responsible for many movements, including flexion, extension, and rotation.
The elbow joint is a hinge joint that joins the bottom of the humerus to the radius and ulna. Several ligaments stabilize the joint and provide flexion and extension of the elbow.
The wrist joint is a hinge joint that connects the radius and ulna to the toe bones. It is stabilized by several ligaments and facilitates wrist flexion and hyperextension.
Ligaments
The elbow and wrist joints each have several ligaments that provide stability and support. For example, the elbow joint has medial and lateral collateral ligaments, and the carpal joint has these ligaments, along with a few others.
Muscles
Like the hind limbs, the front legs have too many muscles to list. Here are some main ones to remember:
- Deltoid: shoulder muscle
- Biceps brachii (equivalent to human bicep)
- Triceps brachii (equivalent to human tricep)
Common Dog Leg Injuries and Issues
As much as we love to see our dogs use their powerful legs to run, jump, and play, dogs commonly experience leg injuries and other issues that can sideline them for a while. Let’s go through some of the most common dog leg injuries:
Broken Bones
Like people, dogs can suffer broken bones. Broken bones cause symptoms like limping, pain, and swelling. Common broken bones in dogs include the femur and humerus. Treatment depends on several factors (e.g., injury severity) and typically requires surgery and post-surgical physical therapy.
Sprains
Sprains occur when a ligament is injured and cause symptoms like lameness and swelling. Without treatment, the sprain could cause muscle weakness and shrinkage. Leg sprains in dogs can usually be treated with rest and pain medication. However, more severe sprains may require surgery.
Patellar Luxation
Patellar luxation occurs when the patella slips (luxates) out of its normal place in a groove at the bottom end of the femur. It is common in toy breeds, such as Yorkshire Terriers. A dog with a luxated patella will skip or run on three legs when the patella slips out of place. Surgery may be warranted if the luxation is causing lameness or leading to other knee injuries.
Cranial Cruciate Ligament (CCL) Injuries
CCL injuries are a common ligament injury in dogs. Dogs with this injury commonly sit with their legs out to the side rather than directly under them. Injury to this ligament makes the knee unstable, leading to pain and difficulty standing up, among other symptoms. Surgery is typically the best treatment for CCL injuries in dogs, with recovery lasting at least 16 weeks.
Achilles Tendon Injury
The Achilles tendon can be injured in several ways, including falls or a penetrating wound. Dogs with this injury experience lameness, pain, and swelling and may walk completely flat-footed if the tendon is completely ruptured. Treatment is either medical, with physical therapy and immobilization, or surgical.
Hip Dysplasia
Hip dysplasia is a genetic condition that affects the hip joint, primarily in large breed dogs. With hip dysplasia, the top of the femur does not fit perfectly into the hip joint, causing painful wear and tear. Dogs with hip dysplasia have lameness, limping, and eventual loss of thigh muscle mass, among many other symptoms. Treatment may or may not require surgery.
Elbow Dysplasia
Elbow dysplasia is another genetic condition and is common in large breeds. Dogs with elbow dysplasia experience lameness after exercise and hold their elbow outward. Surgery is the preferred treatment.
How to Support Your Dog’s Leg Health
Are you still hanging in there? Good! Here are some strategies to keep your dog’s legs as healthy as possible:
Feed your dog a complete and balanced diet. The food you choose should be appropriate for their life stage and size. Dog foods are specifically formulated for small and large breeds, as well as for senior dogs.
Maintain your dog at a healthy weight. Extra pounds put extra pressure on the joints, leading to orthopedic problems. If your dog is overweight, work with your veterinarian to develop a diet and exercise plan to help your dog lose weight and maintain their ideal weight.
Establish a regular exercise routine. Like people, dogs need regular physical activity to prevent excess weight gain and maintain strong bones and muscles.
Prevent jumping on and off furniture. Jumps are a common reason for leg injuries in dogs. The less your dog jumps on and off furniture, the better.
Make your home comfortable for your dog. As your dog ages, their mobility may not be quite as good. Putting sticky pads under the rugs helps prevent slipping, while ramps provide easy and safe access to the couch or up and down the front steps.
