Immune-mediated neutropenia

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Immune-mediated neutropenia is a rare immune-mediated hematological disease of dogs characterized by low circulating neutrophils < 3 x 109/L[1].

A breed predisposition has been noted in the Giant Schnauzer.

Neutropenia is uncommon in dogs[2] and usually occurs as a result of increased demand due to acute severe inflammation (infectious or non-infectious) with a shift of neutrophils from the circulating to the marginal and or tissue pools, immune-mediated destruction of circulating neutrophils, and decreased bone marrow production[3].

Primary immune-mediated neutropenia has been reported to account for less than 1% of all neutropenia cases in dogs[4]. The immunopathology is thought to be due to lymphocytes directed against specific neutrophil membrane antigens or nonspecific surface antigens shared by other hematologic cells.

Secondary immune-mediated neutropenia has been reported in association with:

Clinical signs include anorexia, lethargy and fever due to respiratory or gastrointestinal disorders and sepsis[8]. Affected dogs are generally young adults and females are more commonly affected[9]. Splenomegaly has also been reported with this condition in the Miniature Schnauzer[10].

Hematological assessment of affected dogs shows the characteristic neutropenia but concurrent lymphopenia and thrombocytopenia may also occur. Approximately 25% of dogs idiopathic immune-mediated neutropenia have concurrent thrombocytopenia, thought to be due to antibodies directed against cell surface proteins that are not specific to the neutrophil cell line.

Bone marrow examination typically reveals granulocytic hyperplasia[11].

Diagnosis usually requires demonstration of active bone marrow megakaryocyte production, presence of antineutrophil antibodies, no history of drug administration, exclusion of tick-borne diseases, DIC, neoplasia. However, confirmatory testing is rarely done due to limited availability and the low reliability of these tests in veterinary patients.

A differential diagnosis would include cyclic neutropenia in Collie breeds.

Treatment usually requires long-term therapy with broad-spectrum antimicrobials and low doses doses of prednisolone (1.2 mg/kg daily)[12]. Higher doses of prednisolone may exacerbate underlying infections.

References

  1. McManus PM et al (1999) Immune-mediated neutropenia in 2 dogs. J Vet Intern Med 13:372–374
  2. Peterson ME et al (1996) Pretreatment clinical and laboratory findings in dogs with hypoadrenocorticism: 225 cases (1979–1993). J Am Vet Med Assoc 208:85–91
  3. Stockham SL & Scott MA (2002) Veterinary Clinical Pathology. Vol. 121. Ames, Iowa: Iowa State Univ Press. pp:474
  4. Brown CD et al (2006) Evaluation of clinico-pathologic features, response to treatment, and risk factors associated with idiopathic neutropenia in dogs: 11 cases (1990–2002). J Am Vet Med Assoc 229:87–91
  5. Lifton SJ et al (1996) Glucocorticoid deficient hypoadrenocorticism in dogs: 18 cases (1986–1995). J Am Vet Med Assoc 209:2076–2081
  6. Jacobs G et al (1998) Neutropenia and thrombocytopenia in three dogs treated with anticonvulsants. J Am Vet Med Assoc 212:681–684
  7. Bloom JC, Thiem PA, Selers TS, Deldar A, Lewis HB. Cephalosporin-induced immune cytopenia in the dog: Demonstration of erythrocyte, neutrophil and platelet associated IgG following treatment with cefazedone. Am J Hematol. 1988;28:71–78
  8. Brown MR & Rogers KS (2001) Neutropenia in dogs and cats: A retrospective study of 261 cases. J Am Anim Hosp Assoc 37:131–139
  9. McManus PM et al (1999) Immune-mediated neutropenia in 2 dogs. J Vet Intern Med 13:372–374
  10. Vargo CL et al (2007) Immune mediated neutropenia and thrombocytopenia in 3 giant schnauzers. Can Vet J 48(11):1159-1163
  11. Chickering WR & Prasse KW (1981) Immune mediated neutropenia in man and animals: A review. Vet Clin Pathol 10:6–16
  12. Perkins MC et al (2004) Immune-mediated neutropenia suspected in five dogs. Aust Vet J 82:52–57