Presentation of “fatty liver” or true hepatic lipidosis in cats is unique, characterized by excessive accumulation of triglycerides within hepatocytes and marked cholestasis resulting from biochemical changes induced by such factors as anorexia, insulin resistance, and arginine deficiency. A period of anorexia precedes presentation that may include lethargy, weight loss, jaundice, weakness, vomiting, and diarrhea. Signs of hepatic encephalopathy (eg, excessive salivation) can be present, although rarely so. The history, marked elevation in ALP (>ALT elevation), and minimal change in GGT suggest diagnosis. Other abnormalities may be seen in CBC results (eg, poikilocytosis, Heinz bodies) and serum biochemistry profiles (eg, hyperbilirubinemia, hypokalemia, hypophosphatemia, low BUN). Clotting times may be prolonged, and proteins induced by vitamin K absence or antagonism (PIVKA) are often elevated. The liver is enlarged on radiographs and hyperechoic on ultrasound. Determining underlying disease is essential, as hepatic lipidosis is frequently secondary to another condition, such as pancreatitis, intestinal disease, cholangitis, neoplasia, or infectious disease.
Hepatic lipidosis can be treated primarily through nutrition, frequently requiring an E-tube. Appetite stimulants (eg, mirtazapine) may be contraindicated in cats with hepatic lipidosis because of unknown metabolism variability by the liver. A nasogastric tube may be used while achieving IV fluid support and electrolyte correction during critical care (with attention to potassium, phosphorus, and magnesium), but E-tube use is more common. The cat should be treated with vitamin K1 at 0.5 to 1.5 mg/kg SC q12h for 24 to 48 hours before E-tube placement, fine-needle aspiration of the liver, or obtaining hepatic biopsy specimens. A high-protein, low-carbohydrate diet can be blended and small, frequent feedings initiated, gradually increasing to the cat’s total daily requirement (usually over 4–5 days). Nonspecific supportive care may include maropitant at 1 mg/kg q24h or ondansetron at 0.22 to 0.5 mg/kg q12h (should vomiting occur), continued vitamin K1 at 2.5 mg/cat q24h, cobalamin at 250 µg/cat SC q7d, l-carnitine at 250 mg/cat q24h, and SAMe at 20 mg/kg q24h (increasing the dose by 50% if crushed and given through a feeding tube).
Nonspecific clinical signs and biochemical changes highlight the importance of a diligent diagnostic examination, remembering that although the liver may be the center of the disease process, it might also be only one component of what is making the cat ill.