Page 1068 - Cote clinical veterinary advisor dogs and cats 4th

Icterus 529

anemia; if significant anemia is not present ○ Pre-hepatic: hepatomegaly and spleno- Nutrition/Diet
(packed cell volume [PCV] > 30% in dogs, megaly common with IMHA; evaluate Nutritional support is a key aspect of treatment
VetBooks.ir should be suspected. They are often differenti- ○ Hepatic: hypoechoic hepatic parenchyma is required for treatment of hepatic lipidosis, Diseases and Disorders
for some causes of icterus. Adequate nutrition
> 25% cats), hepatic or post-hepatic icterus
for underlying cause of secondary IMHA
(infectious hepatitis, neoplastic infiltrate),
copper-restricted diets are necessary for copper-
ated with a chemistry profile and abdominal
hyperechoic hepatic parenchyma (neo-
ultrasound.
plasia), hepatic mass, large or small liver associated hepatopathy, and fat-restricted diets
are appropriate for pancreatitis.
Differential Diagnosis (size best assessed on radiographs), chronic
Poor lighting or differences in visual perception hepatopathies may have mild echogenicity Drug Interactions
can give a false impression of icterus; measure- changes (hypoechoic, heterogenous) or Hepatic metabolism and biliary excretion
ment of total bilirubin is confirmatory. may be normal in appearance should be taken into account when prescrib-
○ Post-hepatic: evaluate gallbladder, common ing medications to patients with hepatic and
Initial Database bile duct, and extrahepatic structures/ post-hepatic icterus, respectively.
The myriad causes of icterus are reflected by organs that may result in post-hepatic
variations in test results. Common findings: icterus (e.g., pancreatitis, extramural Possible Complications
• CBC mass); peritonitis with free fluid if biliary • There are multiple possible complications
○ Pre-hepatic: anemia (often regenerative) rupture for the underlying disorders that cause
± autoagglutination ± spherocytes ± icterus.
RBC parasites ± thrombocytopenia ± Advanced or Confirmatory Testing • In people, bilirubin accumulation in the brain
leukocytosis • Infectious disease testing, as appropriate leads to neurologic dysfunction (kernicterus);
○ Hepatic: ± mild anemia ± inflammatory ○ Pre-hepatic: vector-borne disease serology this does not seem to be a problem in dogs
or stress leukogram and polymerase chain reaction (PCR) (e.g., or cats.
○ Post-hepatic: ± mild anemia ± inflamma- babesiosis, cytauxzoonosis)
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tory or stress leukogram ○ Hepatic (dog*; cat ): leptospirosis* Recommended Monitoring
• Chemistry panel (by definition, all demon- microscopic agglutination testing (MAT) • Pre-hepatic: vital parameters (as guide for
strate hyperbilirubinemia) and/or PCR (urine, blood), Histoplasma transfusion need and indicator or throm-
†
○ Pre-hepatic: mild increase in liver enzymes capsulatum urine antigen* , adenovirus*, boembolism), PCV, total solids
†
†
†
due to tissue hypoxia tularemia , toxoplasmosis , calicivirus , • Hepatic: signs of hepatic encephalopathy
○ Hepatic: increased liver enzymes (often bartonellosis* (dull mentation, hypersalivation in cats,
proportional alanine aminotransferase • If effusion present, abdominocentesis and nausea, seizures), appetite, serum biochem-
[ALT] > alkaline phosphatase [ALP], fluid analysis (pp. 1056 and 1343) istry profile, abdominal effusion
gamma-glutamyltransferase [GGT]); • Ultrasound-guided fine-needle aspiration • Post-hepatic: serum biochemistry profile,
potential for decreased in synthetic (FNA) of liver or associated masses (p. 1112) appetite, abdominal comfort
function (glucose, cholesterol, albumin, ○ Often diagnostic for hepatic neoplasia
blood urea nitrogen [BUN]); azotemia (especially round cell neoplasia), hepatic PROGNOSIS & OUTCOME
with leptospirosis. Cats with hepatic lipidosis, and some infectious diseases
lipidosis often have normal GGT. ○ Less useful for chronic hepatopathy, Prognosis depends on the underlying disease
○ Post-hepatic: increased liver enzymes (ALP, hepatotoxicity process and severity of disease, ranging from
GGT > ALT), hypercholesterolemia, • Hepatic biopsy (ultrasound-guided needle excellent (e.g., treatable cause of hemolysis) to
hypertriglyceridemia biopsy, laparoscopic, laparotomy; coagulation grave (end-stage hepatic cirrhosis, metastatic
• Urinalysis: bilirubinuria; hemoglobinuria profile first) neoplasia).
with intravascular hemolysis; proteinuria ○ Histopathology, tissue copper quantification,
with inflammatory or infectious disease and tissue/bile culture if suspect cirrhosis, PEARLS & CONSIDERATIONS
• Coagulation panel (prothrombin time/ chronic hepatitis, copper hepatopathy, or
partial thromboplastin time [PT/aPTT]): neoplasia (if FNA nondiagnostic) Comments
normal to increased (disseminated intra- • Exploratory laparotomy, if certain biliary • Serum bilirubin concentration must be
vascular coagulation secondary to immune- disorders (e.g., bile peritonitis) are greater than 2 mg/dL before icterus can be
mediated hemolytic anemia [IMHA], suspected visualized.
severe hepatic dysfunction, or vitamin • Bile acids testing is generally not useful in
K deficiency) TREATMENT animals with icterus because it does not
• Blood ammonia concentration: may be help to differentiate between hepatic and
increased with hepatic dysfunction Treatment Overview post-hepatic causes of icterus.
• Bile acids: seldom useful in icterus; increased Treatment depends on the underlying cause. • Imaging with abdominal ultrasound is
with hepatic or post-hepatic causes important to differentiate between hepatic
• Abdominal radiographs (may be normal) Acute General Treatment and post-hepatic icterus.
○ Pre-hepatic: check for coin (zinc) in GI • Pre-hepatic: RBC transfusion (packed RBCs • Although theoretically unconjugated
tract; hepatomegaly and/or splenomegaly or whole blood) may be necessary (p. 1169). (indirect) bilirubin is increased more than
may be present with hemolysis • Hepatic: discontinue hepatotoxic drugs, conjugated (direct) bilirubin in animals with
○ Hepatic: microhepatica (chronic hepatopa- address fluid and electrolyte disorders, hemolysis, there is little practical benefit to
thy) or hepatomegaly (neoplasia, infectious treat hepatic encephalopathy (p. 440), treat testing for each type separately (as opposed
hepatitis) suspected infectious disease. to measuring total bilirubin and PCV).
○ Post-hepatic: mass effect in cranial abdomen; • Post-hepatic: bile peritonitis is considered a
loss of serosal detail (pancreatitis, bile surgical emergency. Technician Tips
peritonitis) • An initial PCV is an important test for dogs
• Abdominal ultrasound (most useful in dis- Chronic Treatment and cats presenting with icterus because a
tinguishing between hepatic and post-hepatic Treatment depends entirely on underlying normal PCV helps to rule out pre-hepatic
cause) disease. icterus.

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