Page 441 - Problem-Based Feline Medicine

21 – THE YELLOW CAT OR CAT WITH ELEVATED LIVER ENZYMES 433

Differential diagnosis Increasing depression, weakness and panting occur.
Increasing harsh lung sounds are secondary to worsen-
Toxoplasmosis should be differentiated from other
ing pulmonary edema.
feline systemic infections including feline leukemia
and immunodeficiency viral infections and feline infec- Vomiting and generalized weakness are less common.
tious peritonitis.
Jaundice may occur 3–6 days post-ingestion.
Hemoglobinuria occurs in some cats or a dark brown
Treatment urine containing increased amounts of hemoglobin,
bilirubin and protein may be seen.
Available drugs suppress replication of T. gondii but do
not completely kill the parasite. Death occurs within 18–36 hours of ingestion of a toxic
● Use clindamycin (12.5 mg/kg PO q 12 h) for dose.
3 weeks.
● Cats with ocular inflammation should be judi-
Diagnosis
ciously treated with topical glucocorticoids (topical
0.5 % prednisolone acetate drops q 6–12 h). Diagnosis is based on a history of recent drug exposure
and the presence of “unique” clinical signs.

ACETAMINOPHEN (PARACETAMOL) Anemia is typically non-regenerative within 4–6 days
INTOXICATION of intoxication.
● Heinz-bodies may be visualized with new methyl-
ene blue stain.
Classical signs
● Increased numbers of nucleated red cells reflecting
● Often history of recent drug exposure. hypoxemia may be evident.
● Acute onset of cyanosis, dyspnea and facial
Neutrophilic leukocytosis reflects stress.
edema.
● +/- jaundice occurs several days post- Unexplained and rapid increase in liver biochemical
ingestion. parameters are observed.
● ALT, AST, ALP and total bilirubin concentrations
may be elevated.
Pathogenesis
Histologic examination of hepatic biopsy specimens
Cats have impaired ability to readily metabolize acet- reveals hepatocellular necrosis, lipid accumulation
aminophen. Ingestion of 50–60 mg/kg may be fatal and/or biliary duct proliferation.
for cats. This is equivalent to one child tablet or half
an adult tablet.
Differential diagnosis
Large doses of acetaminophen produce toxic interme-
diates which cause oxidative damage in cells, espe- The features of acetaminophen toxicosis (drug expo-
cially erythrocytes and hepatocytes. sure classic signs, clinico-pathologic findings and acute
● Oxidative damage to hemoglobin leads to methemo- hepatic injury) make most other diseases unlikely.
globinemia and reduced oxygen-carrying capacity.
● Tissue hypoxia and vascular injury occur. Treatment
Hepatic injury is characterized by hepatocellular necrosis. Attempt to minimize drug absorption in acute (< 4
hours) intoxications.
Clinical signs ● Perform orogastric lavages (several cycles each at
5–10 ml/kg of tepid water) to mechanically remove
Pale mucous membranes or acute cyanosis with blue- gastric contents.
tinged mucous membranes, dyspnea, facial edema, ● Give activated charcoal (2 g/kg body weight) to
salivation and depression are typical signs of poisoning. bind residual luminal toxicants via orogastric tube.