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Eccentrocyte Ehrlichia Serologic Testing 1335

Toxicity signs typically seen with values Important Interspecies Differences Pearls
> 2.5 ng/mL, but some dogs can exhibit signs Contraindicated in cats with hypertrophic • Use a lower dose for animals with large body
VetBooks.ir Causes of Abnormally High Levels Drug Effects and renal disease (due to elimination route)
cardiomyopathy
size, obesity (digoxin not distributed in fat),
at lower concentrations.
to avoid toxicosis.
Oral antacids, metoclopramide, phenobarbital,
Overdose
and sucralfate, among others, may decrease • Dosing based on body surface area is
recommended.
Causes of Abnormally Low Levels serum digoxin levels. Several drugs and • The half-life of cardiac glycosides is highly
Correlate with clinical effectiveness, as minimum herbs may increase digoxin concentrations, variable among patients and is often long
effective level not established. Hypokalemia including furosemide, quinidine, tetracycline, (12-20 hours in dogs, 48 hours in cats).
potentiates digoxin-induced arrhythmias. If and verapamil. Consult with pharmacist for
toxicosis is evident but the serum concentration complete list. AUTHOR: Carrie L. Flint, DVM, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
is not excessive, serum potassium should be
evaluated. Specimen Collection and Handling
Serum (red top tube); do not use serum separa-
Next Diagnostic Steps to Consider tor tubes; store at 2°C-8°C.
if Levels are Low
If therapeutic intent is achieved, low levels are Relative Cost: $$
not of concern.

Eccentrocyte

Definition Reference Interval Next Diagnostic Steps to Consider
Erythrocyte damaged by oxidants. Characterized Absent in health if Levels Are High
by focal area of fused membranes with eccentric Evaluate history for source of oxidative damage
displacement of hemoglobinized cytosol and Causes of Abnormally High Levels to erythrocytes.
loss of any central pallor. The collapsed area • Oxidative erythrocyte injury: acetaminophen,
with fused membranes appears as a clear area onions, and benzocaine in dogs and cats, Drug Effects
at periphery of erythrocyte, which is outlined zinc and garlic in dogs. Heinz bodies may Associated with previously used formulations
by a barely visible cell membrane. be seen concurrently. of propofol that contained compound(s) that
• Also reported in dogs with vitamin K induced oxidative damage in dogs and cats
Synonyms antagonist intoxication, T-cell lymphoma,
Bite cell, hemighost and diabetic ketoacidosis. Certain illnesses Specimen Collection and Handling
apparently induce increased formation of EDTA whole blood (lavender top tube) and
Physiology endogenous oxidants, leading to eccentro- freshly prepared blood smear for lab to stain Laboratory Tests Laboratory Tests
During oxidative damage, hemichromes (oxi- cytes in absence of toxins typically associated
dized forms of hemoglobin) bind to the band with oxidative damage. Relative Cost: $$ (reported as part of CBC)
3 protein of the membrane cytoskeleton. This • Decreased antioxidant activity of erythrocytes
creates cross-linking and fusion of the eryth- (rare): congenital deficiency of glucose- AUTHOR: Stephen D. Gaunt, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
rocyte cytoskeleton and alters the membrane, 6-phosphate dehydrogenase, with decreased
with externalization of antigenic proteins and production of reduced nicotinamide adenine
attachment of autoantibodies. Hemichromes dinucleotide phosphate (NADPH) in
can also precipitate to form Heinz bodies. erythrocytes

Ehrlichia Serologic Testing

Definition follow. Granulocytic ehrlichiosis (E. ewingii) is Causes of Abnormally High Levels
Detection of serum antibodies directed against most often associated with either unapparent • The presence of antibodies indicates expo-
Ehrlichia spp. infection or acute, febrile polyarthropathy. sure to E. canis or related organisms. Some
Other species of Ehrlichia may cause infection in tests also detect antibodies to E. ewingii
Physiology dogs or cats with minimal clinical consequence. and E. chaffeensis (human monocytic
Ehrlichia spp. are rickettsial agents that infect ehrlichiosis).
dogs and, rarely, cats. Monocytic (E. canis) Reference Interval • A positive titer is not proof that current
infection can cause acute illness, typically fol- Reporting differs among reference laboratories; clinical signs are due to active infection.
lowed by a long period of subclinical infection. consult with laboratory for proper interpretation • A positive titer may persist indefinitely, despite
In some dogs, chronic disease manifestations of serologic titer. treatment with appropriate antimicrobials.

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