Page 604 - Problem-Based Feline Medicine

596 PART 9 CAT WITH SIGNS OF GASTROINTESTINAL TRACT DISEASE

Metabolized in the liver to glucuronide and sulfate Treatment
conjugates.
Prompt and early treatment is essential.
Cats are deficient in glucuronyltransferase and the
Gastric lavage within 4–6 hours of ingestion.
glucuronidation and sulfation biotransformation routes
are rapidly saturated, causing acute toxicity. Activated charcoal per os.
Hepatic necrosis and methemoglobinemia results. N-acetylcysteine (Mucomyst) 140 mg/kg as a 5% solu-
tion PO or IV as a loading dose, then 70 mg/kg PO or
Fatal methemoglobinemia usually occurs before signs
IV q 4 h for 3–5 additional treatments.
of hepatic necrosis develops.
Ascorbic acid 125 mg PO q 6 h.
Cats are poisoned by as little as 50–60 mg/kg: that is,
one adult tablet. Electrolyte and fluid therapy.
Handle patient with least stress.
Clinical signs
A rough estimate of the methemoglobin content of
Cyanosis and tachypnea. blood can be made by comparing the color of the
patient’s drop of blood against that of a drop of
Salivation and abdominal pain.
blood from a normal cat against a white background
Facial edema and often edema of the paws. (e.g. white absorbent paper). A noticeable brown
coloration compared with normal blood indicates a
Heinz body anemia.
methemoglobin content of more than 10%. This sub-
Chocolate-colored urine (hemaglobinuria, hematuria). jective test can be used to monitor the effectiveness
of treatment and should be performed every 2–3
Jaundice.
hours.
Rapid onset of clinical signs (within a few hours of
Good nursing and maintain body temperature.
ingestion).
Whole blood transfusion if necessary to treat
Death ensues 18–36 hours after ingestion, if
hemolytic anemia.
untreated.
Recovery usually within 48 h.
Diagnosis
History of drug administration.
Prognosis
Characteristic combination of facial edema and
Guarded to poor if severe methemaglobinuria
chocolate-colored urine.
(>50%) or hemolysis.
Heinz bodies on RBCs.
Good with very early and aggressive treatment.
Methemoglobinemia.
Progressive rise in liver enzymes.
LEAD POISONING
Low blood glutathione levels.
Serum acetaminophen concentration maximally ele- Classical signs
vated within 1–3 h after ingestion.
● Gastrointestinal – diarrhea, vomiting,
inappetance.
Differential diagnosis ● CNS signs – behavioral changes,
depression, seizures.
Phenolic and phenolic compound toxicity.
● Occasionally, intermittent ptyalism.
Nitrite poisoning.