Which term indicates a horse with unequal hindquarters?

The term that indicates a horse with unequal hindquarters is "unbalanced." This term specifically refers to a horse whose hindquarters do not match in size, shape, or strength, which can result in uneven movement or performance issues. An unbalanced horse may exhibit problems while walking, trotting, or cantering, as the unequal distribution of weight and muscle can affect its overall gait and athletic ability.

The other terms provided do not express the concept of hindquarter imbalance. "Proportional" usually refers to the overall symmetry and balance of a horse's conformation, suggesting that all parts are in harmony with one another. "Shifty" typically relates more to a horse's temperament or behavior rather than conformation. "Misconfigured" might imply a structural issue but does not specifically denote the unequal proportions found in an unbalanced horse. Therefore, "unbalanced" is the most accurate term to describe a horse with unequal hindquarters.