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4.3 The Neurologic Examination 55

are also likely to be normal. In animals where the paw replacement and/or hopping reactions are
equivocal or difficult to interpret, other postural reactions should be performed. Likewise, if the
nature or the size of the dog precludes accurate assessment of these tests, hemiwalking, for exam-
ple, can be helpful.

Video 4.2:

Neurologic examination – postural reactions.

4.3.5.1 Proprioceptive Positioning and Placing Reaction
During testing of proprioceptive placement, the animal’s weight is supported by the examiner
while the foot is slowly flipped, and the dorsum is gently placed on the ground. The animal should
return the foot to a normal position immediately. Supporting most of the animal’s weight is impor-
tant since this makes it easier to eliminate weakness and orthopedic disease as a reason for a
delayed test. When testing the thoracic limb, the supporting hand is placed under the sternum
(Figure 4.4). More reliable assessment of pelvic limb paw replacement is generally achieved when
a hand is placed ventral and parallel to the pubic symphysis, rather than under the caudal
abdomen.
A similar test, called placing reaction, can be performed by placing the foot on a sheet of card-
board or paper that is slowly pulled laterally (“paper test”). Once an abnormal limb position is
reached, the animal should reposition the foot for normal weight‐bearing. The paw replacement
test is more sensitive for proprioception in the distal extremity, whereas this paper test detects
abnormalities in the proximal limb.
In compressive diseases, abnormalities in proprioceptive placing may be apparent before pare-
sis, because of the superficial position of these pathways. Dogs with PNS disease, on the other
hand, can have normal postural reactions if they still have voluntary motor. They may be too
weak to correct, but if some of the body weight is supported, they can correct normally unlike in
instances of spinal cord lesions, where the animal will be unable to correct even with adequate
support.
Distractions, excitement, or a highly compliant patient can delay paw replacement. In these situ-
ations, hopping reactions should be performed. Dogs with orthopedic disease may appear to have
delayed proprioceptive placing (thought to be due to limb or joint pain that would be associated
with shifting weight or flexing joints) when their body weight is not supported by the examiner. If
orthopedic disease is severe (e.g. femur fracture or severe joint instability) and animals are not
weight‐bearing voluntarily, a lack of correction can be observed even when their body weight is
supported appropriately (Video 4.3). Other factors that can falsely influence results of paw replace-
ment, such as systemic illness or sedation, must be considered during interpretation. Hopping may
be more reliable in these cases.

Video 4.3:

Orthopedic disease mimicking neurologic disease.