Page 1402 - Small Animal Internal Medicine, 6th Edition

1374 PART XIII Hematology

earlier. Oral ulceration, a common feature of neutropenia in Evaluation of changes in a blood smear or analyzer
humans, does not seem to occur in small animals. Neutro- graphics is important for establishing the pathogenesis of
VetBooks.ir penia is frequently an incidental finding in an otherwise the neutropenia. As a general rule, benchtop hematology
analyzers provide total neutrophil counts and do not dis-
healthy dog or cat (i.e., the patient is asymptomatic). If the
neutropenia is caused by peripheral neutrophil consumption
value of evaluating the blood smear. As discussed earlier,
(a septic process), most animals exhibit clinical signs. Dogs tinguish mature neutrophils from bands, reemphasizing the
and cats with parvoviral enteritis have neutropenia in asso- the ProCyte Dx provides a left shift flag; in addition, toxic
ciation with severe vomiting, diarrhea, or both. Cats and neutrophils or bands can easily be recognized by evaluat-
dogs with neutropenia can occasionally present in septic ing the graphics (Fig. 85.3). If a dog or cat has anemia and/
shock (pale, hypoperfused, hypothermic) and should be or thrombocytopenia in association with neutropenia, and
treated aggressively. if the anemia is nonregenerative, a primary bone marrow
The evaluation of neutropenic cats and dogs should disorder should be strongly suspected. If a dog or cat has
include the following: regenerative anemia and spherocytosis in association with
neutropenia, an immune-mediated disease or hemophago-
• Detailed drug history (e.g., estrogen or phenylbutazone cytic malignant histiocytosis should be considered in the
in dogs, griseofulvin in cats; see Box 85.1) differential diagnoses.
• Vaccination history (e.g., was the cat vaccinated against The presence of toxic changes in the neutrophils or a
panleukopenia or the dog against parvoviral enteritis?) left shift (see later) tend to suggest infection; that is, toxic
• Complete physical examination and imaging in search of changes and left shifts are typically absent in dogs and
a septic focus cats with steroid-responsive neutropenia or primary bone
• Serologic, virologic, or molecular tests for infectious dis- marrow disorders. In a study of 248 dogs with toxic neutro-
eases (e.g., feline leukemia virus, feline immunodeficiency phil changes conducted in Israel (Aroch et al., 2005), dogs
virus, canine ehrlichiosis and anaplasmosis, parvoviral with pyometra, parvoviral infection, peritonitis, pancreati-
enteritis, etc.) tis, and septicemia were significantly, and not surprisingly,
• If necessary, bone marrow cytologic or histopathologic more likely to have toxic changes than those in the control
studies group. The mortality rate was significantly higher in the dogs

WBC Run WBC Run

Fluorescence Fluorescence

Granularity Granularity

NEU LYM MONO EOS BASO URBC NEU LYM MONO EOS BASO URBC

FIG 85.3
Leukocyte graphics (dot plots) from a ProCyteDx depicting left shift/neutrophil toxicity in a
dog with sepsis (left) and in a normal dog (right). Notice the absence of individual clouds
and the straight line between the neutrophil (purple) and lymphocyte (blue) populations
and between the lymphocyte (blue) and monocyte (red) populations. You can see the
remaining normal lymphocyte population bulging on the left of the lymphocyte cloud. The
wide monocyte cloud also reflects left shift/toxicity and/or activated or reactive
monocytes.