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1336 Eosinophils Erythrocytosis

Next Diagnostic Steps to Consider Important Interspecies Differences Pearls
if Levels Are High Check with lab for use of canine tests on feline • Some dogs maintain persistent titers for years
VetBooks.ir Causes of Abnormally Low Levels Laboratories, Westbrook, ME) test for dogs • Point-of-care serologic testing appears to
patients. The point-of-care SNAP® (IDEXX
despite appropriate therapy and apparent
See p. 285.
resolution of disease.
can be used on cats.
Acute infection (before antibody formation);
infection with Ehrlichia spp. not reactive on Specimen Collection and Handling have high specificity when compared with
immunofluorescent assay, but may not detect
test; uninfected animal Serum (red top tube, 1 mL); stable at 2°C-8°C low titers.
for up to five days, or follow manufacturer’s • Ehrlichia serologic testing is much more
Next Diagnostic Steps to Consider directions for point-of-care tests. sensitive (i.e., better screening test) than
if Levels Are Low evaluating a blood smear for the presence
If a clinical suspicion for ehrlichiosis persists, Relative Cost: $$ of ehrlichial inclusions (i.e., morulae) in
consider either alternative forms of testing (e.g., leukocytes.
PCR, different serologic test), repeat testing in
2 weeks, or empirical treatment. AUTHOR: Sharon M. Dial, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP

Eosinophils

Definition inflammation (e.g., hypereosinophilic syndrome, also other sighthounds and a few golden
Granulocytic leukocyte with prominent eosino- eosinophilic bronchitis); hypoadrenocorticism retrievers), eosinophils have clear vacuoles
philic granules in cytoplasm and a segmented (“relaxed” leukogram, which is the unexpected with a more apparent basophilic cytoplasm
nucleus absence of stress leukogram with eosinopenia (instead of many eosinophilic granules),
in an ill patient); paraneoplastic (e.g., mast which are described as “gray eosinophils.”
Physiology cell neoplasm, B or T cell lymphoma); chronic • Feline eosinophils have distinctive rod-shaped
Eosinophilic precursors develop in the marrow eosinophilic leukemia (rare) eosinophilic granules. Cats with gray eosino-
under influence of interleukin 5 (IL-5). phils are reported rarely.
Mature eosinophils are released into blood Next Diagnostic Steps to Consider
to circulate for a few hours and then enter if Levels Are High Drug Effects
tissue. Eosinophils contain major basic protein, Use history and physical exam findings to assess Glucocorticoids cause increased sequestra-
which is important in attacking helminthic for causes listed. tion of eosinophils in tissues, with resultant
parasites. Eosinophils can both promote and eosinopenia.
inhibit hypersensitivity reactions. Eosinophilic Causes of Abnormally Low Levels
inflammation occurs most often in cutaneous, Stress leukogram from endogenous or exogenous Specimen Collection and Handling
respiratory, and intestinal tissues. glucocorticoids; acute inflammation EDTA whole blood (lavender top tube) and
freshly prepared blood smear for lab to stain
Reference Interval Next Diagnostic Steps to Consider
3
Dogs: 0.1-1.3 × 10 eosinophils/mcL; cats: if Levels Are Low Relative Cost: $$ (reported as part of CBC)
3
0-1.5 × 10 eosinophils/mcL Low values are rarely clinically significant.
AUTHOR: Stephen D. Gaunt, DVM, PhD, DACVP
Causes of Abnormally High Levels Important Interspecies Differences EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
Parasitism (e.g., dirofilariasis, larval migration • In canine eosinophils, the granules are
in tissues); allergic reactions (e.g., flea bite round and can vary considerably in size
hypersensitivity); idiopathic eosinophilic and number. In some dogs (greyhounds, but

Erythrocytosis

Definition erythrocytes and erythropoietic cells (absolute of sequestered erythrocytes following
Increased circulating erythrocyte mass, with erythrocytosis) epinephrine-induced splenic contraction.
increased hematocrit (or packed cell volume • Absolute erythrocytosis indicates an
[PCV]), hemoglobin concentration, and/or Physiology increase in circulating and erythropoietic
blood erythrocyte count. Occurs from increase • Relative erythrocytosis occurs most com- cells as a result of increased erythropoietin
in the circulating erythrocytes only (relative monly when there is decreased plasma concentration or heightened response to
erythrocytosis) or an increase in both circulating volume (e.g., dehydration) or with release erythropoietin.

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