Page 884 - Problem-Based Feline Medicine

876 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

Normal sympathetic innervation is responsible for Radiographs of the bulla may show increased opacity
pupillary dilation. or bony abnormalities if middle ear disease is present.
Any disease that interrupts sympathetic transmis- Advanced imaging studies (computed tomography
sion to the eye can result in Horner’s syndrome. (CT) or magnetic resonance (MR) imaging) are used to
● Infiltration of these nerves by lymphoma or look for intracranial, middle ear or spinal disease.
leukemia cells is possible.
Cerebrospinal fluid should be collected and evaluated
● Traumatic damage to the sympathetic system can
for protein content and cellularity.
occur.
If a cervical spinal cord problem is suspected, spinal
Many instances of Horner’s syndrome in cats do not
radiographs, myelography, or advanced imaging (CT,
have a definable cause.
MR) may be needed.

Clinical signs Differential diagnosis

Unilateral or bilateral miosis is the most consistent Primary disease of the eye such as anterior uveitis
clinical sign of sympathetic denervation. should be ruled out by performing a thorough ocular
examination.
The affected pupil will not dilate normally in a dark
environment. A neurologic examination should be performed to rule
out associated intracranial or spinal disease.
Other clinical signs constituting a diagnosis of
Horner’s syndrome include prolapsed third eyelid,
enophthalmus, ptosis, and rarely, vasodilation of uveal
Treatment
tract vessels.
If middle or inner ear disease is present, pain and As Horner’s syndrome is a clinical diagnosis and not
swelling around or ventral to the bulla may be present. an etiological diagnosis, any disease of the sympathetic
There may also be pain upon opening the mouth, system should be treated specifically.
swelling in or around the ear, and abnormal discharge No treatment is available for idiopathic Horner’s syn-
in the ear canal may be present. drome.

Diagnosis Prognosis
The clinical diagnosis is based upon the presence of The ultimate prognosis will depend upon the underly-
this constellation of characteristic clinical signs how- ing cause.
ever, these clinical signs are not pathognomonic for any
The prognosis for otitis media is good with appropriate
particular disease.
surgical or antimicrobial treatment.
Pharmacologic testing of the eye to determine the
The prognosis for brain and spinal cord disease
location (pre- or postganglionic) of the disease is rarely
depends upon the nature of these diseases.
helpful.
Cats with idiopathic Horner’s syndrome may improve
An otoscopic examination should be performed to
with time.
examine for signs of middle ear disease.
Idiopathic Horner’s syndrome is not life threatening.
Palpation in the cervical area around the vagosympa-
thetic trunk should be performed to check for masses or While being a cosmetic abnormality, Horner’s syn-
other abnormalities. drome is infrequently irritating to the cat.