Postural Reactions
The postural reactions assess the innate sense of being aware of the precise position and movements of any part of the body, called proprioception or kinesthesia. This function requires 3 major sensory components:
- PROPRIOCEPTORS: special receptors located in joints, tendons and muscles.
- ASCENDING PROPRIOCEPTIVE TRACTS: peripheral nerve, spinal cord, brainstem.
- CEREBRAL CORTEX: conscious perception in the contralateral cerebral hemisphere
The postural reactions assess not only the 3 previous components of the afferent pathway, but also motor components descending in the opposite direction (efferent pathway) from the brain to the limbs inducing movement of the limb. The 2 postural reactions most frequently used are PROPRIOCEPTIVE POSITIONING and HOPPING.
Proprioceptive Positioning:
Evaluated by turning over the paw and placing the dorsal surface in contact with the ground. A normal patient should immediately replace its foot in a normal position. The test is repeated several times until we are confident with the results. Animal’s weight should be supported. All 4 limbs are tested individually.
Hopping:
Evaluated in each limb holding off the ground the contralateral limb, so the majority of the weight is put on the limb to be assessed, while the patient is pushed laterally (not medially). A normal patient will hop on the assessed limb to accommodate a new body position while is displaced laterally.