Page 896 - Problem-Based Feline Medicine

888 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

non-diagnostic for chronic organophosphate toxicity. Treatment
Values less than 500 IU/L (normal 900–1200 IU/L) are
If the drug was administered locally in the eye, stop-
considered consistent with organophosphate toxicity.
ping additional administrations and allowing time for
Diagnosis of snake bite depends on the type of snake. the drug to be metabolized in most sensible as this is
Weak cats with mydriasis and evidence of rhabdomyol- rarely life threatening for the animal. It may take 1–2
ysis (markedly elevated creatine kinase) or coagulopa- weeks for normal pupil responses to return.
thy (bleeding from venepuncture sites or increased
activated clotting time) should be suspected if the snake
SPONGIFORM ENCEPHALOPATHY
bite is from an Elapid (cobra type) snake if in the right
geographical location and season.
Classical signs
History of recent fluoroquinolone use, especially of
● Dilated pupils in association with other
doses higher than the recommended dose of 5 mg/kg q
clinical signs including muscle tremors,
24 h.
ataxia, jaw clamping, salivation and
behavior abnormalities.
PARASYMPATHOLYTIC DRUGS
Pathogenesis
Classical signs
There is vacuolation within areas of the central nerv-
● Mydriasis with or without dry mouth,
ous system.
tachycardia, and ileus or constipation may
be seen. No causative agent has been identified.
Speculation of an infectious agent (prion) as in other
spongiform encephalopathies as a cause has been sug-
Pathogenesis gested.
Some drugs or toxins prevent or reverse stimulation of
Clinical signs
the parasympathetic receptors. Atropine would be
a commonly used example. Dilated pupils.

Other signs include muscle tremors, ataxia, jaw
Clinical signs clamping, salivation and behavior abnormalities.
If there is only local stimulation of the eye, mydriasis is Signs may progress to severe ataxia and hypermetria.
likely to be the only clinical sign.
Diagnosis
If systemic parasympathetic stimulation occurs,
other clinical signs could include dry mouth, tachycar- Definitive diagnosis is made only at necropsy and
dia, ileus or constipation. histologic examination of the nervous system.

Differential diagnosis
Diagnosis
Rule out other causes of mydriasis.
Determining a history of instillation or administra-
tion of these drugs is the only practical way of diag-
Treatment
nosing this problem.
No treatment has been used.
Differential diagnosis Prognosis

Rule out other causes of mydriasis. Affected cats have died or been euthanized.