Forty-five cases of canine Achilles mechanism disruption were reviewed, mostly involving medium-sized dogs, among which dobermanns, labradors and border collies were most commonly represented. Most cases were acute in onset (66.7 per cent), and were usually closed injuries (75.6 per cent). In the majority of cases, the damage involved all tendons (26.7 per cent), all tendons except the superficial digital flexor tendon (22.2 per cent), or the gastrocnemius alone (20 per cent). Damage most commonly occurred at the tendo-osseous junction (60 per cent), with injury occurring less commonly at the musculotendinous junction (20 per cent) or in the body of the tendon (13.3 per cent). A plantigrade posture was not predictive of involvement of specific tendons, but was more likely if the injury involved the musculotendinous junction. The most common method of treatment was a primary tendon repair using polydioxanone suture in a locking-loop pattern, with placement of a temporary calcaneotibial screw and cast. The outcome was not significantly influenced by whether the injury was open or closed, the duration of the injury, the tendons involved, or the method of repair. Complications were recorded in 16 cases (35 per cent), of which 10 were minor and six major. Complications were significantly more likely if the damage involved the body of the tendon. Long-term follow-up was available for 19 dogs; the outcome of surgery was considered to be good to excellent in 18 dogs.

Despite the cheetah being the fastest living land mammal, we know remarkably little about how it attains such high top speeds (29 m s )1 ). Here we aim to describe and quantify the musculoskeletal anatomy of the cheetah forelimb and compare it to the racing greyhound, an animal of similar mass, but which can only attain a top speed of 17 m s. Measurements were made of muscle mass, fascicle length and moment arms, enabling calculations of muscle volume, physiological cross-sectional area (PCSA), and estimates of joint torques and rotational velocities. Bone lengths, masses and mid-shaft cross-sectional areas were also measured. Several species differences were observed and have been discussed, such as the long fibred serratus ventralis muscle in the cheetah, which we theorise may translate the scapula along the rib cage (as has been observed in domestic cats), thereby increasing the cheetah's effective limb length. The cheetah's proximal limb contained many large PCSA muscles with long moment arms, suggesting that this limb is resisting large ground reaction force joint torques and therefore is not functioning as a simple strut. Its structure may also reflect a need for control and stabilisation during the high-speed manoeuvring in hunting. The large digital flexors and extensors observed in the cheetah forelimb may be used to dig the digits into the ground, aiding with traction when galloping and manoeuvring.