| Line 9: |
Line 9: |
| | ==[[Body, Spinal Cord and Limb Neurological Examination - Horse]]== | | ==[[Body, Spinal Cord and Limb Neurological Examination - Horse]]== |
| | | | |
| − | ===Conscious Proprioception Testing ===
| |
| − |
| |
| − | * It is possible to test a horse’s conscious proprioception by altering the position of the limbs in space.
| |
| − | ** Horses should normally replace their limbs to the normal position within a few seconds.
| |
| − | *** There is a degress of individual variability, however, and the test can be difficult to interpret.
| |
| − | * Tests can also be performed by walking or trotting a horse and then suddenly stopping.
| |
| − | ** The animal should be observed to see how quickly it replaces its legs in a normal position.
| |
| − |
| |
| − | ===Gait===
| |
| − |
| |
| − | * Gait is a combination of higher control of motor function and unconscious proprioception.
| |
| − | * During assessment of gait, the examiner is looking primarily for evidence of '''ataxia''' and/ or '''weakness'''.
| |
| − | ** Each leg should be assessed in turn.
| |
| − | * Defects may be graded on a five-point scale (the Mayhew scale).
| |
| − | ** 0 is normal and 5 is recumbent.
| |
| − |
| |
| − | ====Ataxia====
| |
| − |
| |
| − | * Defects in unconscious proprioceptive pathways result in ataxia.
| |
| − | ** These pathways originate in muscle spindle stretch receptors and golgi tendon organs.
| |
| − | ** Impulses are relayed via peripheral nerves to the spinal cord.
| |
| − | ** Signals then ascend in pathways to the cerebellum.
| |
| − | *** Primary cerebellar diseases in horses are rare, but classically cause incoordination of the head and limbs.
| |
| − | **** Weakness is not a prominent feature.
| |
| − | **** The cerebellum communicates with the vestibular nuclei, and so cerebellar diseases may sometimes present with vestibular signs.
| |
| − | * Manifestations of ataxia:
| |
| − | ** Exaggerated movements - hypermetria
| |
| − | ** Reduced movements - stilted hypometric movements
| |
| − | ** Both exaggerated and reduced movements - dysmetria.
| |
| − | * Animals may also
| |
| − | ** Sway
| |
| − | ** Place their feet abnormally
| |
| − | *** Horses cross or weave their feet, with abnormal abduction or adduction.
| |
| − | * Signs of spinal ataxia may be exaggerated by lifting the horse's head.
| |
| − | ** This is beacuse it removes the horizon.
| |
| − | ** Similar responses can be generated by walking up and down slopes.
| |
| − | * Circling the horse can also reveal ataxia.
| |
| − | ** The horse may plant its feet and rotate around them without placing them properly.
| |
| − | ** Outward rotation of the pelvic limbs is also a common sign.
| |
| − | *** The term for this is "circumduction".
| |
| − | * Unconscious proprioception may also be tested by backing the horse.
| |
| − | ** Normal horses back with a diagonal gait.
| |
| − | ** Horses with spinal ataxia will often pace when backing.
| |
| − |
| |
| − | ====Weakness====
| |
| − |
| |
| − | * Weakness usually manifests as toe dragging, stumbling, or knuckling over.
| |
| − | ** It is a good idea to look closely at the horse’s hooves to see if any are abnormally worn.
| |
| − | * Weakness may be caused by dysfunction of either the upper or lower motorneurons.
| |
| − | ** Lower motor neuron weakness.
| |
| − | *** Accompanied by:
| |
| − | **** Muscle flaccidity
| |
| − | **** Muscle atrophy if chronic
| |
| − | *** May sometimes appear similar to lameness.
| |
| − | ** Upper motor neuron weakness.
| |
| − | *** Presents as a lack of control of limb muscle movement.
| |
| − | *** Tested most easily tested by pulling the tail during walking.
| |
| − | **** Pulling the tail while stationary probably primarily tests lower motor neuron control and muscular strength of the pelvic limb.
| |
| − |
| |
| − |
| |
| − | [[Category:Neurological Examination - Horse]]
| |
| | | | |
| | | | |