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693.e2 Neutropenia, Immune-Mediated

Neutropenia, Immune-Mediated Client Education
Sheet
VetBooks.ir

BASIC INFORMATION
marrow evaluation is usually necessary to
decide and determine appropriate treatment metric Neutrophil Surface Antibody Flow
test.
Definition and prognosis. Usually, immune-mediated • Any concurrent drug therapy should be
Antibody-mediated destruction of neutrophils neutropenia is a diagnosis of exclusion. stopped if possible to rule out adverse drug
and/or their precursors in the marrow, result- reaction.
ing in a decrease in the absolute number of Differential Diagnosis • Response to treatment with corticosteroids
circulating neutrophils • Secondary neutropenia, often with toxic may allow retrospective diagnosis of immune-
changes on blood smear, is usually associated mediated neutropenia.
Synonym with severe illness and may improve within
Steroid-responsive neutropenia days of appropriate antibiotic treatment; TREATMENT
conversely, primary neutropenia persists
Epidemiology after an infection is treated. Treatment Overview
SPECIES, AGE, SEX • Primary but nonimmune-mediated neutro- Assume sepsis exists when fever and neutropenia
• Rare cause of neutropenia but more common penia are present concurrently, regardless of the cause
in dogs than cats ○ Bone marrow abnormality such as aplasia, of the neutropenia. Intensive treatment with
• Any age; female dogs < 4 years old may be fibrosis, dysplasia, or neoplasia; neutrope- IV bactericidal antibiotics is indicated because
at increased risk. nia occurs first, then thrombocytopenia sepsis can be rapidly fatal. Glucocorticoids can
and anemia be added later if primary immune-mediated
GENETICS, BREED PREDISPOSITION ○ Infections such as parvovirus or ehrlichiosis disease remains the most likely diagnosis by
• One report involved three female giant in dogs and retroviruses (FeLV, FIV) or exclusion.
schnauzers. panleukopenia in cats
• Cats and Belgian Tervuren dogs may have ○ Hyperestrogenism from testicular or Acute General Treatment
physiologic neutropenia without clinical signs. ovarian tumors or iatrogenic estrogen • Weigh risks and benefits, and rule out
administration other causes of neutropenia before starting
RISK FACTORS • Cyclic neutropenia in gray collies is a rare glucocorticoid therapy.
Drugs (phenylbutazone, griseofulvin [cats]) cause of neutropenia, as is trapped neutrophil • Use appropriate antibiotics based on C&S
or infectious agents (viruses, rickettsiae) are syndrome of Border collies. if fever is present. Empirical antibiotic
sometimes implicated. • Some normal cats may have neutrophil treatment may be necessary initially (first
counts between 1800 and 2500/mcL. few days) while C&S is underway.
ASSOCIATED DISORDERS ○ In severely ill patients, IV antibiotics
Sometimes concurrent anemia, thrombocytope- Initial Database should be used. Options include cefoxitin
nia, or pancytopenia or other immune-mediated • CBC: if the neutropenia is associated with 30 mg/kg IV q 6-8h, or ampicillin 20 mg/
diseases other cytopenias or it persists for more than kg IV q 8h plus enrofloxacin 5 mg/kg
2-3 days (if < 1000/mcL neutrophils) or (diluted 1 : 1 with sterile saline and given
Clinical Presentation 1 week (if 1000-2000/mcL), bone marrow slowly IV) q 12h (5 mg/kg q 24h in cats).
HISTORY, CHIEF COMPLAINT aspiration and biopsy are indicated. ○ In severe sepsis, consider temporary use
• Sometimes an incidental finding on CBC ○ Neutrophil counts are usually < 500/mcL of human granulocyte colony-stimulating
for healthy pets at presentation for immune-mediated factor (G-CSF 5) mcg/kg SQ q 24h.
• Lethargy or anorexia may be reported. neutropenia. Development of antibodies prevents
• Signs may arise from infections, usually • Serum biochemistry profile and possibly long-term benefits.
bacterial from invasion of normal flora. thoracic and abdominal radiographs may ○ In stable cases, oral trimethoprim-sulfadiazine
• Clinical signs are nonspecific and usually disclose an underlying disorder (infection 15 mg/kg PO q 12h is often suitable because
are not helpful in localizing infections. or neoplasia) causing secondary neutropenia. it preserves normal intestinal anaerobes.
○ Serum chemistry profile is usually unre- Trimethoprim-sulfadiazine has rarely been
PHYSICAL EXAM FINDINGS markable, although hyperglobulinemia implicated as a cause of neutropenia.
Fever and weakness may be the only findings. may be present. • Prophylactic antibiotic treatment may be
Sometimes signs of opportunistic infections ○ Possible thoracic radiographic lesions warranted even for afebrile animals with
(e.g., diarrhea, gingivitis, skin lesions) may (e.g., mediastinal or pulmonary disease) severe neutropenia.
be present. if secondary infection present • Prevent infection by paying special attention
• Urinalysis with bacterial culture and suscep- to sterile technique with IV catheters and
Etiology and Pathophysiology tibility (C&S) to evaluate for urinary tract other invasive procedures.
• Idiopathic; possibly genetic predisposition; infection • Start prednisone at 2 mg/kg PO q 24h
not well studied after infectious causes have been ruled out
• Drugs or infections occasionally implicated Advanced or Confirmatory Testing or treated. Continue until neutrophil count
• Abdominal ultrasonography to evaluate for is normal.
DIAGNOSIS evidence of neoplasia or infection • If risk of ehrlichiosis, consider doxycycline
• Serologic testing for relevant infectious 5-10 mg/kg PO q 24h while awaiting
Diagnostic Overview diseases serologic test results.
Neutropenia may be primary or secondary • Antineutrophil antibodies have been
to an overwhelming infection. Determining demonstrated by flow cytometric immu- Chronic Treatment
which exists in a given patient is of paramount nofluorescence. • With immune-mediated neutropenia, neu-
importance. A combination of physical exam, ○ The University of Tennessee CVM trophil count should increase < 2 weeks of
CBCs, diagnostic imaging, and often bone Diagnostic Laboratory offers a flow cyto- prednisone therapy.

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