Page 1066 - Cote clinical veterinary advisor dogs and cats 4th

528 Icterus

• Animals can require long-term mechanical diseases requiring longer-term mechanical Technician Tips
ventilation for lung injury. Appropriate set- • Prognosis is good for animals if a reversible • Venous [CO 2 ] is less accurate if cardiac
ventilation.
VetBooks.ir Recommended Monitoring cause (e.g., drugs, tick paralysis, laryngeal because tissue CO 2 production increases with
output or tissue perfusion is compromised
tings, analgesics, fluid therapy, and nursing
care can minimize complications.
paralysis) is rapidly identified and treated.
malperfusion.
• Oxygenation: arterial blood gas or pulse PEARLS & CONSIDERATIONS • ETCO 2 is lower than PaCO 2 in conditions
where CO 2 delivery is altered by severe
oximetry parenchymal disease, low cardiac output,
Comments or thromboembolic disease.
• Ventilation: blood gases or ETCO 2
• Blood pressure: invasive versus noninvasive • Peripheral chemoreceptors initiate ventilation
• Appropriate mechanical ventilator settings during periods of hypoxemia. Therefore, the SUGGESTED READING
• Monitor for clinical signs of volume overload use of high-inspired oxygen concentrations Daly M: Hypoventilation. In Silverstein D, et al,
(e.g., chemosis, serous discharge) can worsen hypercapnia in chronically editors: Small animal critical care medicine, ed 2,
hypercapnic patients. St. Louis, 2015, Saunders.
PROGNOSIS & OUTCOME • Oxygen therapy can also decrease hypoxic AUTHOR: Meghan Harmon, DVM, DACVECC
pulmonary vasoconstriction, which prevents EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
• Prognosis depends on the severity, presence blood from entering alveoli with low
of comorbidities, and reversibility of the ventilation. Decreasing this reflex increases
underlying disease process. ventilation-perfusion mismatch.
• Client finances and access to 24-hour specialty
care may alter prognosis for neuromuscular

Icterus Client Education
Sheet

BASIC INFORMATION • Cats: feline infectious peritonitis, toxoplas- • Post-hepatic: GI signs, anorexia, abdominal
mosis*, tularemia* pain, lethargy
Definition
Yellow discoloration of the tissues that results GEOGRAPHY, SEASONALITY PHYSICAL EXAM FINDINGS
from bilirubin deposition when the serum Some infectious causes of icterus are more In addition to icterus (mucous membranes,
bilirubin level exceeds 2.0 mg/dL. Causes common in a given region or season. sclera, skin), other common findings include
can be categorized as pre-hepatic, hepatic, or • Pre-hepatic: pale mucous membranes,
post-hepatic. ASSOCIATED DISORDERS tachycardia; tachypnea, bounding pulses,
• Pre-hepatic: hemolytic anemia, thromboem- soft systolic heart murmur
Synonym bolic disease • Hepatic: hepatomegaly or hepatic mass,
Jaundice • Hepatic: coagulopathy, hepatic encephalopathy abdominal distention with fluid wave
• Post-hepatic: pancreatitis, triaditis (cats), gall- • Post-hepatic: abdominal pain, tachycardia,
Epidemiology bladder mucocele, coagulopathy, peritonitis tachypnea, fever
SPECIES, AGE, SEX
• Dogs and cats of any age, either sex Clinical Presentation Etiology and Pathophysiology
• Pre-hepatic and post-hepatic causes of icterus DISEASE FORMS/SUBTYPES • Pre-hepatic: red blood cell (RBC) destruc-
are more common in dogs than cats. Categorized as pre-hepatic, hepatic, and post- tion releases heme, which is broken down
hepatic based on the underlying mechanism to bilirubin. With accelerated hemolysis,
GENETICS, BREED PREDISPOSITION for hyperbilirubinemia: bilirubin production overwhelms the ability
Based on underlying disorder • Pre-hepatic: hemolytic anemia of any cause of the liver to conjugate and secrete it into
• Hepatic: liver damage or disease (inflamma- bile.
RISK FACTORS tory, infectious, neoplastic, toxic), sepsis • Hepatic: abnormality in hepatic bilirubin
• Pre-hepatic: risk of hemolytic anemia of any • Post-hepatic: intrahepatic or extrahepatic uptake, conjugation, and/or excretion
cause (pp. 59 and 60) cholestasis or biliary rupture • Post-hepatic: obstructive biliary disease
• Hepatic: risk of hepatic disease or injury of (intrahepatic or extrahepatic) results in
any cause (pp. 174, 442 and 444) HISTORY, CHIEF COMPLAINT reduced bilirubin excretion in bile or rupture
• Post-hepatic: risk of biliary obstruction Although rare, jaundice may be noticed by of biliary tree, allowing abnormal release
(including pancreatitis) or rupture (pp. 160, owners. Most patients present because of of bile.
374, 740, and 742) clinical signs associated with the underlying
disease that has resulted in hyperbilirubinemia. DIAGNOSIS
CONTAGION AND ZOONOSIS Common signs:
There are many infectious but noncontagious • Pre-hepatic: clinical signs associated with Diagnostic Overview
causes of icterus; contagious causes (zoonosis*) anemia (e.g., lethargy, collapse) Icterus is a clinical feature that is always second-
include • Hepatic: acute or chronic lethargy, anorexia, ary to a primary disease/condition and always
• Dogs: canine infectious hepatitis, leptospi- weight loss, gastrointestinal (GI) signs (e.g., warrants thorough diagnostic investigation.
rosis*, salmonellosis* vomiting, diarrhea) The first step is a CBC to check for hemolytic

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