Page 2293 - Cote clinical veterinary advisor dogs and cats 4th

Ophthalmic Examination 1137

Always compare the thoracic limbs with small dogs and cats. Place the patient between ○ Ocular position and movement
■
each other and then the pelvic limbs your thighs and hold its head while testing ■ Observe the position of the eyeballs for
VetBooks.ir the pelvic limbs normally tends to be perform this cranial nerve exam on larger cent, VI) and adduction (oculomotor,
the function of the cranial nerves. You can
with each other because the response in
strabismus, and test abduction (abdu-
slower than that of the thoracic limbs.
dogs by straddling them so that you and the
III) nerve function by moving the head
side to side while observing the eyes.
For very large dogs, it is easier to make
■
Proper evaluation requires a relaxed, almost
the same observations while the dog is dog are both looking in the same direction. ■ Look for a resting nystagmus. If not
hemiwalked. motionless patient. Use a regional approach, present, look for a positional nystagmus
For hemiwalking, stand beside the starting with the eyes: with the head held flexed laterally to
■
patient, and pick up the ipsilateral ○ Menace response either side and then extended dorsally.
thoracic and pelvic limbs so they are ■ The menace response assesses vision Occasionally, it is worthwhile to look
located at your side. Then push the and facial nerve function as long as for this sign with the patient placed in
patient gently away. the stimulus of the hand thrust at dorsal recumbency.
These hopping responses are much more the patient’s face does not touch the ○ Trigeminal nerve (V)
■
reliable than the paw replacement test. face or whiskers or create excessive air ■ Palpate the muscles of mastication
• Spinal reflexes: for spinal reflex testing, the movement. (motor, V) for denervation atrophy. Procedures and Procedures and Techniques Techniques
patient should be placed in lateral recumbency. ■ If there is no response, be sure the ■ Recheck the palpebral reflex by stimu-
○ Manipulate the limbs to assess muscle eyelids are able to close (i.e., there is lating the lateral and medial canthi
tone. no facial paralysis). with blunt forceps (sensory, V; motor,
○ With the patient relaxed and the stifle ■ If there is a normal palpebral reflex or VII).
slightly flexed, elicit the patellar reflex spontaneous eyelid closure but still no ■ Place the blunt forceps against the
by tapping on the patellar tendon. If menace response, tap the eyelids or face nasal septum on each side to assess
it is not present in one or both limbs, gently to get the patient’s attention, and the ophthalmic (V) and the nociceptive
always place the patient in the opposite then repeat the menace gesture. pathway to the opposite somesthetic
recumbency, and repeat the patellar reflex ■ Failure to close the eyelids to a menace cortex.
before concluding that it is absent. Some in a patient > 10 weeks old with normal ■ Observe for ear movement and lip
old dogs with no neurologic complaints facial nerve function or the lack of symmetry and tone (VII).
lack the patellar reflex. This is the only eyeball or head retraction in a patient ■ Open the mouth to assess muscle tone
reliable tendon reflex because the other with facial paralysis indicates a lesion in (motor, V) and range of motion.
myotactic reflexes (e.g., triceps, biceps, some part of the visual pathway from ○ Glossopharyngeal (IX), vagus (X), and
extensor carpi radialis) may not be present the eyeball to the occipital lobe. hypoglossal (XII)
in some normal animals. ■ Patients with significant cerebellar ■ Observe the tongue for its size and
○ The withdrawal-flexor reflex is routinely disorders that have no menace response movements (XII).
tested by gently compressing the base of are still visual. ■ Place one finger in the oropharynx to
the claw in each paw with forceps and ■ Assessing the menace response before determine the muscle tone and the
observing the strength of the limb flexion shining a light in the patient’s eyes patient’s response to the presence of
and the patient’s response (e.g., abrupt avoids falsely compromising the menace the finger—the gag reflex (IX and X).
turning, vocalization) to the noxious response with the glare of the light.
stimulus. NOTE: The sensory modality ○ Pupil size and pupillary light reflex Postprocedure
that is tested is not pain. A noxious ■ With a strong light source, assess the By establishing the anatomic diagnosis (location
stimulus is used, and what is observed size and symmetry of the pupils from of the lesion in the nervous system), the results
is the patient’s reaction to this conscious a distance. of the neurologic exam allow a differential
perception (nociception). Pain is the ■ Bring the light to about 1-2 cm from diagnosis to be established and a diagnostic
patient’s response to a noxious stimulus. the eye, and swing it from one eye to plan to be created.
It is often difficult to determine a patient’s the other and back again.
response to a minimal noxious stimulus, ■ Repeat this to be sure that with the SUGGESTED READING
and there is no practical value to differ- light in one eye, the pupils of both de Lahunta A, et al: Veterinary neuroanatomy and
entiating the patient’s response to light eyes are constricting. clinical neurology, ed 3, St. Louis, 2009, Saunders.
and strong noxious stimuli (pp. 1257 ■ Deficits in this light reflex implicate
and 1258). a lesion in the eye/optic nerve (optic AUTHOR: Alexander de Lahunta, DVM, PhD, DACVIM,
• Cranial nerves: sitting down on the floor with chiasm or tracts) and/or the general DACVP
EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
your back against the wall and knees flexed visceral efferent component of the Thompson, DVM, DABVP
is the best position from which to evaluate oculomotor nerve.

Ophthalmic Examination

Difficulty level: ♦ the need for additional diagnostic testing or • Vision impairment/loss
referral • Systemic disease that may have ocular
Overview and Goal manifestations
Basic examination of the structure and func- Indications
tion of the eyes and adnexa (surrounding • An abnormal appearance to the eye(s) or Contraindications
structures) to establish an ophthalmic diagnosis, adnexa A very aggressive patient, particularly with a
prognosis, and treatment plan and to evaluate • Ocular discomfort or trauma fragile eye, may not tolerate an awake ocular

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