Page 893 - Problem-Based Feline Medicine

40 – THE CAT WITH ANISOCORIA OR ABNORMALLY DILATED OR CONSTRICTED PUPILS 885

flexion of the neck, but do not cause dilated pupils acting parasympathomimetic, physostigmine (0.02
unresponsive to light. mg/kg IV) produces no ocular response, but direct-
acting pilocarpine (topically) results in immediate miosis,
DYSAUTONOMIA** demonstrating post-glanglionic denervation hypersensitiv-
ity. Normal cats do not demonstrate these responses.
Classical signs
Differential diagnosis
● Younger cats (< 3 years).
● Acute onset of depression and anorexia. Differential diagnoses are many, depending on the
● Dilated pupils, xerostomia, predominant signs. Cats may present with a history of
keratoconjunctivitis sicca, prolapsed third constipation or inability to urinate or dilated pupils,
eyelids. suggesting disease of the colon, lower urinary tract or
● Bradycardia. eyes. Typical cases which exhibit most signs are classi-
● Megacolon, constipation, loss of anal cal for dysautonomia.
reflex.
● Incontinence, dysuria or distended bladder. Treatment
● Weakness.
No specific treatment is available, but supportive
See main reference on page 792, “The Constipated or care is important, such as syringe or tube feeding
Straining Cat”. and maintenance of fluid and electrolyte balance.
The urinary bladder should be emptied regularly to pre-
Clinical signs vent distention and urinary tract infection.

Disease is confined to Europe or occurs in imported Parasympathomimetic agents may improve some clini-
cats. The prevalence has decreased markedly and it is cal signs.
now uncommon. ● Pilocarpine ophthalmic drops (state frequency)
may result in pupillary contraction and increase
Younger cats (< 3 years) are more often affected.
salivation.
Clinical signs are often acute in onset over 48 hours ● Bethanechol (1.25–5 mg PO q 8–12 h) may bene-
with all cats showing depression and anorexia. fit constipation and urinary retention.
● Metoclopromide (0.2–0.5 mg/kg PO, SC, q 8 h)
Other signs reflect autonomic system dysfunction
may improve gastric motility.
and include ocular, gastrointestinal and urinary tract
signs. Up to a 70% mortality rate has been reported and sur-
viving cats may have residual dysfunction such as uri-
Ocular signs include fixed, dilated pupils without
nary or fecal incontinence and pupillary abnormalities.
blindness, prolapsed third eyelids and dry eyes (kerato-
conjunctivitis sicca develops).
Gastrointestinal signs include regurgitation, megae- NEOPLASIA*
sophagus, constipation and megocolon, loss of the anal
reflexes, dry mouth (xerostomia). Classical signs
Bradycardia (90–120 beats/min). ● ± Mydriasis.
● Circling, seizures, behavior abnormalities,
Dysuria and/or distended bladder or incontinence.
paresis or cranial nerve abnormalities.
Generalized weakness. ● ± Discharge from the ear.

Diagnosis Pathogenesis

Diagnosis is based primarily on clinical signs and Neoplastic disease may infiltrate or compress the
evidence of autonomic dysfunction. The indirect- cranial nerve III centrally or peripherally.