As you may have noticed, your four-legged friend moves about the cabin by walking on his toes. This is particularly apparent if you observe his entire rear foot while he is walking or standing still. His toes make contact with the ground, but his heel appears to be above the floor and jutting out slightly behind him. This little bony projection has a big job to do to provide your dog with his smooth stride.
Foot Bones Connect to the Shin Bones
If you trace your finger from the ground up along the back of your dog’s foot, you will come to a point that juts out. This area is referred to as the hock, which is the joint that connects the foot to the shin portion of your dog’s leg. The shin bones are the tibia and the fibula. The connecting foot bones are the talus and the calcaneus. The bony protrusion is the calcaneus, and it is also present in cats and horses. Humans share similar structures, but our calcaneus, which we commonly refer to as the heel bone, touches the ground to balance and support our bipedal movement.
From Calcaneus Bone to Calcaneal Tendon
The bones that make up your dog’s hock joint are held together with flexible connective tissues called ligaments. Attached to the calcaneus bone is the common calcaneal tendon, or Achilles tendon, which connects to muscle that enables your dog to flex his hock. The Achilles tendon keeps the calcaneus bone off of the ground. It is actually a complex structure, made up of five tendons. The two significant tendons include the gastrocnemius, which attaches to the calcaneus bone, and the superficial digital flexor, which arcs over the back of the calcaneus bone to split off into the four tendons that connect to the bones of the four toes. The remaining tendons of the Achilles tendon include the biceps femoris, the gracilis and the semitendinosus. )
Injuries and Disorders of Achilles Tendons
Although any size dog or cat can sustain an Achilles tendon injury, incidences are more prevalent in large adult dogs. The most common injuries to the Achilles tendon fall into two categories, traumatic and degenerative. Traumatic injuries that result in ruptures, tears and dislocation include laceration of the tendon tissues, blunt force trauma and extreme straining. Examples of how traumatic injuries can happen include exposure to broken glass or other sharp objects, being struck by a car, being stepped on by a human or getting the foot caught in something that requires a struggle to get free. Achilles tendon injuries can also occur as the result of a degenerative condition within the tendon. This is seen most commonly in Doberman pinschers.
Signs of Tendon Trouble
If your dog has an Achilles tendon injury or calcaneus bone fracture, you will notice limping or lameness in his hind limb. Swelling around the hock may also be noted. If the gastrocnemius tendon alone is torn, his hock will be partially dropped. If the entire Achilles tendon is severed, his hock will be completely dropped, making him appear to walk flat-footed on that limb. The toes will curl during his attempts to walk as his foot tries to bear extra weight. If you notice any of these signs, schedule an appointment with your veterinarian immediately. He may refer your dog to a board certified veterinary orthopedic surgeon to repair the injury. Seeking treatment within the first week after the injury will ensure the most favorable healing outcome for your canine companion.
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