Page 860 - Clinical Small Animal Internal Medicine

828 Section 8 Neurologic Disease

have been reported. Long‐term prognosis is poor even Both cats and dogs can be affected, although the disease
VetBooks.ir with treatment aimed at the underlying cause. is much more prevalent in cats. A geographic distribu­
tion has been suggested, with most affected cats living in
the United Kingdom and most affected dogs living in
Dysautonomia (Key–Gaskell the American Midwest. Animals tend to be young and
or Dilated Pupil Syndrome) have a rapid onset (two days to two weeks). Although
there is no known cause, 50% of cats in one study did test
Dysautonomia is a rare, idiopathic condition in which positive for Clostridium botulinum type C.
there is generalized loss of autonomic nervous system Diagnosis of dysautonomia is generally accomplished
function secondary to degeneration of parasympathetic through the overt clinical signs. Pharmacologic testing as
and sympathetic neuronal ganglia. Ophthalmic clinical described previously for internal ophthalmoplegia and
signs may be the first observed and include bilateral Horner’s syndrome can be completed. In cases of dysau­
mydriasis with absent PLR, elevated third eyelids, ptosis, tonomia, application of dilute pilocarpine will induce
and decreased tear production. Dysautonomia can be pupillary constriction and application of dilute epineph­
readily differentiated from Horner’s syndrome by the rine or phenylephrine will allow third eyelid retraction.
presence of mydriasis rather than miosis. Nonocular Treatment for dysautonomia is supportive. Prognosis for
clinical signs may include xeromycteria, xerostomia, dys­ survival is poor, with 75–85% of animals succumbing to the
phagia, vomiting, regurgitation, gastric distension, ano­ disease or being euthanized due to the difficulty in mainte­
rexia, diarrhea, bradycardia, constipation, and urinary nance of supportive care. Some cats have spontaneously
bladder distension. recovered, although this is rare and should not be expected.

Further Reading

Harkin KR, Andrews GA, Nietfeld JC. Dysautonomia in Theisen SK, Podell M, Schneider T, Wilkie DA, Fenner
dogs: 65 cases (1993–2000). J Am Vet Med Assoc 2002; WR. A retrospective study of cavernous sinus syndrome
220(5): 633–9. in 4 dogs and 8 cats. J Vet Intern Med 1996; 10(2):
Mayhew PD, Bush WW, Glass EN. Trigeminal neuropathy 65–71.
in dogs: a retrospective study of 29 cases (1991–2000). Webb A, Cullen C. Neuro‐ophthalmology. In: Veterinary
J Am Anim Hosp Assoc 2002; 38(3): 262–70. Ophthalmology. Ames, IA: John Wiley & Sons, 2012,
Nell B. Optic neuritis in dogs and cats. Vet Clin North Am pp. 1821–68.
Small Anim Pract 2008; 38(2): 403–12.