Page 306 - Problem-Based Feline Medicine

298 PART 5 CAT WITH ACUTE ILLNESS

Diagnosis HYPERNATREMIA

Elevated plasma ammonia level confirms hepatic
encephalopathy; but a normal fasting concentration Classical signs
does not rule it out.
● Coma, twitching, seizures.
Porto-systemic shunts have variable hematologic and
biochemical findings, which may include low normal to Pathogenesis
low MCV, low urea, albumin, glucose and cholesterol
concentrations, and elevated globulin and bile acid con- Hypernatremia results from excessive sodium intake
centrations. Imaging may reveal a small liver and the and/or inadequate water intake and/or excessive water
shunt. Definitive diagnosis may require an exploratory loss.
laparotomy.
Hypernatremia in cats is most likely to occur in criti-
Hepatic lipidosis and cholangiohepatitis are typi- cally ill cats receiving sodium-rich fluids that have con-
cally associated with increased ALT and/or ALP. A current sodium-poor water loss (e.g. diabetes mellitus,
disproportionate elevation of ALP compared to ALT head-trauma induced central diabetes insipidus).
and GGT is suggestive of hepatic lipidosis. Elevations
in serum bile acids in the absence of cholestasis con-
firm the presence of liver dysfunction. Coagulation Clinical signs
abnormalities may be present. Imaging may reveal an
Acute progressive lethargy in a critically ill cat.
enlarged, hyperechoic liver. Definitive diagnosis relies
on liver biopsy. May progress to coma, twitching, and seizures.
Dehydration.
Differential diagnosis Weak pulse, prolonged capillary refill time and
hypothermia may be present.
The main differential diagnosis for ptyalism is oral cav-
ity ulceration.
The main differential diagnoses for icteric depressed Diagnosis
cats are acute pancreatitis and diabetic ketoacidosis.
Serum sodium level > 160 mmol/L.
The main differential diagnosis for transient depression
Ruling out other causes of depression and anorexia.
and disorientation is poisoning.
Urine specific gravity < 1.035 may indicate diabetes
insipidus.
Treatment

Hepatic encephalopathy treatment includes lactulose, Differential diagnosis
enema, lactulose retention enema, correction of
hypokalemia, and antibiotics (neomycin, metronida- Other causes of depression and anorexia related to the
zole, ampicillin/amoxicillin). primary disorder causing critical illness.
Porto-systemic shunts can often be reduced or closed
by partial or complete surgical ligation or placement of Treatment
an ameroid constrictor.
Sodium-poor intravenous fluids. Hypernatremia
Hepatic lipidosis requires nutritional support.
should be corrected at the same rate at which it devel-
Cholangiohepatitis treatment includes nutritional sup- oped, i.e. serum sodium concentration should be
port, antibiotics if an organism is cultured, and corcor- lowered rapidly in acute hypernatremia, and slowly in
ticosteroids if lymphocytic-plasmacytic inflammation chronic hypernatremia. Overly rapid correction of
is evident on biopsy. hypernatremia will result in signs similar to hyperna-