Surgery and Radiology Section

TYPES OF SPINAL REFLEXES

Myotatic (Stretch) reflex : or Quadriceps (Knee Jerk, Patellar) reflex

• Keep the animal in lateral recumbency, suppor the limb under the femur with the left hand.
• The patellar ligament is struck crisply with the plexor. The response is a single quick extension of the stifle. 

Cranial tibial reflex

• With the animal in lateral recumbency the examiner tests the cranial tibial reflex.
• The belly of the cranial tibial muscle is struck in the plexor just distal to the proximal end of the tibia. The response is flexion of hock.

Gastrocnemius reflex

• The gastrocnemius reflexes are tested after the cranial tibial reflex.
• The tender of the gastrocnemius muscle is struck with the plexor, just dorsal to the tibial dorsal bone.
• Slight flexion of the hock is necessary for some tension of muscle to be maintained. The response is extension of hock.

Extensor carpi radialis reflex

• In  lateral recumbency the limb is supported under elbow with flexion of the elbow and the tension to be maintained .
• The extensor carpi radialis muscle is struck with a plexor just distal to the elbow. The response is slight extension of the carpus.

Triceps reflex

• Under lateral recumbency, the triceps brachiae muscle is struck with  plexor, just proximal to the olecranon.
• The response is a slight extension of the elbow or a visible contraction of muscle.

Biceps reflex

• The index or middle finger of the examiner’s hand that is holding the animal’s elbow is placed on the biceps and the brachialis tendons cranial and proximal to the elbow.
• The elbow is slightly extended and the biceps is struck with the plexor. The response is flexion of the limb

Flexor (pedal, with drawl) reflexes

• Pelvic limb: Under lateral recumbency, a noxious stimulus is applied to the foot.
• The normal response is a flexion of entire limb including the hip, stifle and hock.

Extensor thrust reflex

• Under lateral recumbency or with the animal suspended by the shoulders with the pelvic limbs hanging free.
• The toes are spread and slight pressure is applied between the pads. The response is a rigid extension of the limb.

Perineal (Bulbocavernosus, Anal) reflex

• The perineal reflex is elicited by light stimulation of the perineum with forceps (painful stimuli usually are not necessary).
• The response is a contraction of the anal sphincter muscle and flexion of the tail.

Crossed extensor reflex

• The crossed extensor reflex may be observed when the flexor reflex is elicited.
• The response is an extension of the limb opposite the stimulated limb.

Extensor toe (Babinski- plantar) reflex

• Under lateral recumbency, the pelvic limb is held proximal to the hock with the hock and the digits slightly flexed.
• The handle of the plexor or a forceps is used to stroke the limb on the caudolateral surface from the hock to the digits.
• The normal animal exhibits no response or a slight flexion of the digits.