Page 822 - Problem-Based Feline Medicine

814 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

– Lead poisoning induces gastrointestinal (anorexia, cats are rare. Hypoglycemia is typically associated
vomiting, diarrhea, constipation), renal (polyuria, with insulin overdose in a diabetic patient, hypocal-
polydipsia) and neurological (depression, central cemia is mainly seen after bilateral thyroidectomy,
blindness, hyperexcitability, running fits, seizures, and hepatoencephalopathy causes episodic signs,
vocalization, ataxia, head pressing, opisthotonos, which rarely occur in intoxications.
paraparesis) signs. Megaesophagus with regurgita-
Inflammatory conditions (e.g. encephalitides,
tion and pharyngeal/laryngeal paresis has been
polyneuropathies) need to be ruled out. Usually his-
observed with chronic lead poisoning in cats.
tory and physical examination findings differentiate
– Bromethalin acute toxicity causes tremors,
these from intoxications.
hyperexcitability, hyperesthesia, depression,
fever, anisocoria, positional nystagmus, extensor
rigidity, opisthotonos and seizures (running fits Treatment
and generalized). Death may sometimes be
With dermal exposure it is important to bath the cat
delayed up to 2–3 weeks in cats. Chronic intox-
with soap or detergent to remove the toxin from the hair
ication with lower dosages causes occasional
and skin. Intoxication with anti-flea and -tick sprays,
vomiting, ascending paresis and ataxia with pro-
dips, and aerosols containing insecticides such as
prioceptive deficits, depressed spinal reflexes
pyrethrins, carbamates, organophosphates often occurs
(patellar and withdrawal), tremors, depression
via dermal exposure.
and lateral recumbency. Recovery is possible
after exposure is discontinued. When ingestion has occurred within the previous
– Penitrem mycotoxins. 2 hours, emesis may be indicated or contraindicated,
according to the specific toxin and formulation that was
ingested. Emesis may be induced with hydrogen perox-
Diagnosis
ide 3% (2 ml/kg PO) or apomorphine (0.03–0.04 mg IV
Diagnosis is based on a history of exposure to a toxin or 0.04–0.08 mg/kg IM). Gastric lavage performed
capable of producing the observed signs within the doc- under general anesthesia may be beneficial if emesis is
umented time for exposure. not effective. Enemas also may be useful. Activated
charcoal (0.1–1.0 mg/kg q 8–12 h) preferably adminis-
Toxicologic analysis may be diagnostic when per-
tered with a cathartic such as magnesium sulfate (250
formed on the following:
mg/kg) or 70% sorbitol (3 ml/kg) is also indicated to
● Tissues (e.g. liver, kidney, fat, brain) for organochlo-
reduce gastrointestinal absorption.
rines, organophosphates, strychnine, lead, etc.
● Vomitus and stomach content (for bromethalin, Atropine sulfate (0.02–0.04 mg/kg IM or SC) will
strychnine, methaldehyde). decrease salivation and muscarinic signs associated
● Urine (for strychnine). with organophosphate and other poisoning, but because
● Blood for lead concentration and acethyl- of the risk of fatal bronchospasm it is only recom-
cholinesterase activity (organophosphate poisoning). mended if marked bradycardia is present.

Toxicity as a cause of seizures can be excluded when Pralidoxime chloride (2-PAM, Protopam chloride) is
(a) there are no other diffuse neurological signs preced- useful to reactivate cholinesterase (10–15 mg/kg IM or
ing the seizure onset (e.g. tremors, hyperexcitability), (b) SC q 8–12 h) and control nicotinic signs of organophos-
when partial seizures occur, (c) when isolated seizures phate poisoning. It is most effective if exposure was
are interspersed with periods of normalcy, or (d) when within the previous 24–48 hours, if exposure was by the
focal neurological signs or deficits are present. dermal route and if a slowly eliminated compound was
involved (e.g. fenthion, chlorpyrifos).
Differential diagnosis Diphenhydramine also has antinicotinic activity.
Metabolic disturbances that are severe enough to Chelation therapy (e.g. calcium EDTA and/or penicil-
cause obvious neurological signs including seizures in lamine) is indicated for lead poisoning.