Achilles' tendon tears may be partial or complete and can cause severe debilitation of hindlimb function.

Surgery is frequently needed to treat this condition. The limb must be supported in a cast or other fixation to minimize tension on the healing tendon for about two months after surgery.

The prognosis generally is favorable and function after healing takes place is usually good.

What is it?

• The Achilles’ tendon is also known as the common calcanean tendon.  It is not a single tendon, but is consists of a group of five tendons which include the gastrocnemius, the superficial digital flexor (SDF), and three less important small tendons. The gastrocnemius is the major component of the Achilles’ tendon.  Under normal conditions, the gastrocnemius is responsible for extending the hock (ankle) and flexing the stifle (knee). The SDF is primarily responsible for flexing the digits (toes), but also aids in extension of the hock.
• Achilles’ tendon ruptures can either be complete or partial tears. When the complete tear occurs the gastrocnemius tendon is torn from its attachment on the heel bone and the SDF portion is torn so that it no longer passes over the heal bone (typically in the region circled in the photo right). In partial tears, only the gastrocnemius portion is torn.

How does it occur?

• Achilles’ tendon rupture may occur suddenly due to a traumatic event such as a fall or a penetrating wound.  A laceration is more apt to cause a complete tear of the tendons, or they may occur over time due to extreme overstretching and overuse which can cause the tendon to deteriorate and eventually tear. The chronic form of this injury is more commonly seen in large sporting or athletic breeds. This injury can, however, occur in any breed of dog or cat. It has been more commonly seen in dogs 5 years of age and older, but may occur at any age. Doberman pinschers have been reported to have this injury in both the right and left hind limb more so than other breeds and it is not currently known why this occurs.

Clinical Signs

• Varying degrees of lameness are noted, but a complete Achilles' rupture is usually more debilitating. The region of the tendon tear usually is swollen.
• Gastrocnemius tendon rupture with SDF intact:
  • with a partial tear the SDF is usually intact but the gastrocnemius tendon is torn this causes the animal to walk low in the hocks but its toes will be flexed like it is tip toeing; it has been called a “bear claw stance”.
  • See photo right with curling of toes
• Complete Achilles' rupture
  • If the injury is a complete tear of the Achilles’ tendon, both the gastrocnemius and SDF tendons are torn from the heel bone causing the animal to walk with the hocks in maximal flexion (with hocks completely dropped, so that the ‘ankles’ touch the ground like a human would walk and not on the paw like cats and dogs usually do).

Diagnosis

• Findings on physical examination are helpful in diagnosing the problem. Radiographs (x-rays) of the hock (ankle) are helpful to rule out other skeletal problems such as dislocation or fracture of bones in the heel or ankle. Ultrasound may also be used to differentiate between complete and partial ruptures and to determine where the rupture has occurred.

How is it treated?

• Conservative management of partial and complete Achilles’ tendon rupture is rarely, if ever, successful thus surgical correction is necessary. Splinting in cases of very minor tears may be tried.
• Prior to surgery, the animal’s activity should be restricted to reduce further injury. The surgical procedure involves removing the damaged portions of the tendon so that the ruptured ends can be reattached together. To reattach the gastrocnemius tendon to the heel bone, bone tunnels are drilled and special nonabsorable sutures are passed through the tunnels and into the gastrocnemius tendon. If the SDF tendon is also ruptured the ruptured portions are stitched back to one another using heavy suture material in a special suture pattern (locking loop) that pulls the torn tendon ends back together. 
• After the tendon(s) have been repaired, the patient must keep the ankle (hock) in extension for a period of two months, so that the surgery does not fail. After two months the method of stabilization of the hock is removed. Methods to do this are listed below:
• Placement of a screw through the tibia and heal bone with the hock in extension; a cast is usually also applied to the limb
• Placement of an external skeletal fixator which consists of a series of pins that penetrate the bone and are fixed together with external bars
• Placement of a circular fixator ring with wires
• Placement of a cast
• During the ninth and tenth week a soft padded bandage is typically is used to allow for further healing and support.
• If the injury is not corrected in a timely manner the ruptured tendon will be harder to fix because more scar tissue is formed around the end that was torn and more tendon will need to be removed to allow reattachment. If the animal walks plantigrade (like a human with toes and ankle on the ground) for an extended period of time further damage can result which will make surgery more difficult.

Home Care

• Postoperatively the patient is sent home with medications to control pain and inflammation and may also be sent home with antibiotics to be given for a specific time period.
• You will need to limit your pet’s activity for at least 12 weeks which means short walks on a leash to urinate and defecate only.  Your pet should not be allowed to jump, run, climb stairs, or play roughly with other pets and/or people as this could cause the surgical repair to break down.
  
• Cast care:
  • If a cast has been applied it is important that it be kept clean and dry.
  • A plastic bag should be placed over the cast when the dog is taken outdoors, but it should be removed when the animal is inside.
  • It is essential that your pet ’s toes be checked twice daily for swelling and coldness and if they occur notify your veterinarian.
  • It is important to have the inner cast padding changed every 2 weeks by a veterinarian.
  • Signs of problems with a cast may include the following:
    • The pet licks or chews at the cast
    • The cast has a foul odor
    • Discharge is seeping through the cast
    • Cold toes
    • Swollen toes
    • Cast has slipped down the limb
    • Cast is wet
    • If any of these problems is seen, please notify your veterinarian immediately as the cast will need to be changed earlier than the 2 week recheck.
• External fixator care: If an external fixator has been applied to support the surgical repair site it is necessary to properly care for the fixator unit. Daily care for the external fixator involves cleaning around the pin sites until no more discharge is seen and applying triple antibiotic ointment until the skin surrounding the pins has healed.  To protect the external fixator unit, foam sponges can be packed around the pins and the bars of the external fixator wrapped with an Ace bandage. If the external fixator unit seems loose please notify your veterinarian as this could compromise healing.

Potential Complications

• Anesthetic death is very uncommon with our sophisticated monitoring devices and advanced anesthesia protocols.
• Pressure sores are a potential complication of having a cast or splint. If the animal is trying to chew off or lick at the cast, if the cast has a foul odor or if there is discharge coming through the cast a pressure sore maybe the likely cause.  If any of these signs occur please notify your veterinarian.
• Break down of the surgical repair may occur if your animal’s activity level is not restricted and the cast/bandage is not kept on for the appropriate amount of time.
• Infection is an uncommonly seen complication.  If you notice swelling or coldness in the exposed toes of the operated limb in the cast please notify your veterinarian as they may be signs of infection.

Prognosis

• If appropriate treatment is performed and postoperative instructions, especially exercise restriction, are followed the animal has a good prognosis for returning to normal function. It is important to keep in mind that for most animals the healing process takes about 8-10 weeks.
  
  

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