CONDITION
Carpal Hyperextension Injury
Carpal hyperextension injury describes damage to the ligaments and other soft tissues that normally hold the carpus — the joint roughly halfway down the front leg, analogous to the human wrist — in its correct position. When these structures are stretched or torn, the joint may drop closer to the ground during weight-bearing, sometimes to the point where the back of the paw lifts and the dog or cat appears to be walking on the underside of the joint itself. Owners often notice a sudden change in how the leg looks during walking or standing, particularly after a fall, a jump from height, or an awkward landing. The limb may appear bent in an unusual direction, and the animal may carry weight reluctantly on that leg or avoid using it altogether. In some cases the change is subtle at first, becoming more apparent as the animal tires or moves at speed. This page explores the signs that may be observed, what happens to the structures inside the joint when this injury occurs, how the condition is investigated through examination and imaging, and the range of approaches — from rest and support through to surgical reconstruction — that exist depending on the severity and the individual animal's circumstances.
Why this matters now
Carpal hyperextension injury can occur at any age, but the circumstances that lead to it often differ between life stages. Young, active dogs and cats may sustain this injury during high-energy play, falls from furniture or fences, or awkward landings after jumps. Older animals with degenerative changes in ligament tissue may experience similar damage from lower-impact events that would not have caused injury in their younger years. Certain breeds with lighter bone structure or hypermobile joints may be somewhat more prone to ligament strain, though the injury is observed across all sizes and conformations.
The course of a carpal hyperextension injury depends largely on the degree of soft-tissue disruption and whether the animal continues to bear weight on the affected limb. In cases where only mild stretching has occurred, signs may stabilise or improve over weeks as inflammation settles and surrounding muscles compensate. When ligaments are partially or completely torn, continued weight-bearing tends to worsen the drooping of the joint, and the limb may progressively lose its normal contour. Some animals develop a lasting change in gait, redistributing load to other limbs, which can in turn affect the shoulders, elbows, or opposite forelimb over months.
Signals & patterns
Early signals
Altered leg profile during standing
The carpus may appear lower to the ground than usual when the animal stands still, giving the leg a slightly collapsed or bowed appearance. This can be subtle and may only be visible when comparing one limb to the other.
Reluctance to bear full weight
The dog or cat may shift weight away from the injured leg, favouring the opposite forelimb or sitting down frequently. This reluctance often becomes more pronounced after rest or first thing in the morning.
Mild swelling around the joint
The area around the carpus may feel slightly thicker or warmer to the touch, reflecting fluid accumulation and inflammation in the tissues surrounding the joint. The swelling is often diffuse rather than sharply localised.
Slight lameness at speed
A limp that is barely noticeable during slow walking may become clearer when the animal trots or runs, as the joint struggles to stabilise under increased load. The gait may look choppy or uneven.
Later signals
Pronounced joint drop during walking
The back of the carpus may descend far enough that the animal appears to be walking on the underside of the joint, with the paw angled upward. This plantigrade stance is often most obvious when the animal is tired or moving across uneven ground.
Persistent non-weight-bearing lameness
The animal may hold the leg up entirely during movement, using only three limbs. This pattern suggests either significant pain or structural instability that makes weight-bearing mechanically difficult.
Thickening or firmness of the lower foreleg
Chronic inflammation and the body's attempt to stabilise the joint through scar tissue can lead to a palpable increase in the bulk of the soft tissues around the carpus. The area may feel less mobile when gently moved.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
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