While supporting the pelvic limbs, the pet should be hopped on one thoracic limb while the other thoracic limb is held off the ground. The pet should be moved laterally. Limb strength and coordination should be observed in comparison with one another. The clinician should observe the lateral aspect of the thoracic limb being tested; the limb should move as soon as the shoulder is moved laterally over the paw. Any delay, irregularity, or exaggeration in this response is abnormal. Delayed hopping (symmetric or asymmetric) may occur with a motor (UMN or LMN) or sensory (GP) lesions. Commonly, both the UMN and GP systems (e.g., brainstem and spinal cord diseases) are affected simultaneously and the abnormal hopping response is a reflection of both (e.g., UMN/GP deficits). Lesions in the GP system or cerebellum may produce exaggerated responses.
Hopping responses in the pelvic limbs should be evaluated similarly. While supporting the chest and thoracic limbs, one pelvic limb should be held up and the dog or cat hopped laterally on the supporting limb. The pelvic limb hopping responses should be compared with one another (not to thoracic limbs). Typically, pelvic limb hopping responses are more spastic, with a slightly larger excursion than the thoracic limbs.