Page 1297 - Problem-Based Feline Medicine

62 – THE CAT WITH ABNORMAL PUPIL SIZE, SHAPE OR RESPONSE 1289

Diagnosis is confirmed by demonstration of a mono-
Classical signs—Cont’d
clonal globulin spike on protein electrophoresis.
● Dot-like opacities on the endothelial
surface of the cornea or the anterior
FELINE DYSAUTONOMIA
capsule of the lens.
● Thin strands of iris tissue crossing the
Classical signs
pupil space.
● Variable ocular signs, including reduced
lacrimation, dilated non-responsive pupils,
anisocoria, prolapsed third eyelids, Pathogenesis
photophobia. The pupillary membrane is a mesodermal embryonic
● Other systemic signs such as constipation, structure, which, until regression, forms a solid sheet of
vomiting and regurgitation, dry mouth or tissue bridging the pupil space and the anterior chamber.
dry nostrils.
The pupillary membrane arises from the iris collarette.
AU: For more details see main reference on page 792 (The In adult cats, the collarette appears as a slightly raised
Data region halfway between the pupil margin and the iris root.
missing Constipated or Straining Cat) or page 203 (The Incon-
tinent Cat). The pupillary membrane remains as persistent
strands of tissue in the anterior segment of the eye, if
Clinical signs it fails to rarify in late fetal life.

Ocular signs are due to abnormalities of autonomic
innervation to eye structures and can include reduced Clinical signs
lacrimation, dilated non-responsive pupils, anisoco-
ria, prolapsed third eyelids and photophobia in a cat Fibrous strands of iris-like tissue extend from the iris
with vision. collarette (raised area approximately half way between
the iris root and the pupillary margin) to either another
Other systemic signs such as constipation, vomiting region of the collarette, the anterior capsule of the
and regurgitation, dry mouth or dry nostrils are re- lens, or the posterior corneal surface (most com-
lated to effects of the disease on autonomic nerves sup- monly). The strands can be very thin, and magnifica-
plying secretory glands or the gastrointestinal system. tion may be required to visualize them.

Typically, the onset of signs is acute over 48 h and Dot-like gray to black opacities may be visible on the
associated with depression and anorexia. endothelial surface of the cornea or the anterior capsule
Rare disease, and most common in the United Kingdom. of the lens, and are associated with strands attaching
the opacity to the iris. The opacities are unassociated
Diagnosis with a history of previous inflammation within the eye.

The disease can be suspected in any cat showing com- The condition is rare in cats compared to the fre-
binations of the clinical signs. quency with which it is seen in dogs, and rarely seems
to affect the pupillary light reflex or pupil shape.
Definitive diagnosis is based on histopathology of auto-
nomic ganglia at necropsy. Diagnosis

PERSISTENT PUPILLARY MEMBRANE (PPM) Diagnosis is based on the characteristic appearance
of the persistent pupillary membranes on careful ocular
examination.
Classical signs
● Strands of iris-like tissue arising from the Differential diagnosis
iris collarette and crossing the pupil space,
or attaching to the cornea or lens. The gray opacities formed by persistent pupillary mem-
branes, which attach to the corneal endothelium should