Thrombocytopenia

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Pale mucous membranes in a Cocker Spaniel with immune-mediated thrombocytopenia[1]

Thrombocytopenia in dogs is defined as a reduced levels of circulating thrombocytes (platelets) below the normal cut-off value of 2 x 1011/L.

Thrombocytopenia may result from reduced platelet production, increased platelet sequestration, increased platelet utilization or destruction. Consumptive coagulopathies represent the most common cause of increased platelet utilization, whereas immune-mediated thrombocytopenia, either primary or secondary, is the most common cause of increased platelet destruction[2].

Causes of canine thrombocytopenia include:

- Dirofilaria immitis[3], Angiostrongylus vasorum[4][5], Rickettsia spp, Leishmania infantum[6], Ehrlichia canis[7], Borrelia burgdorferi, Babesia rossi[8], Anaplasma phagocytophilum[9]

Clinical symptoms associated with this condition include lethargy, fever, melena, hematemesis, hematuria, hematochezia, epistaxis and mucosal petechiations or ecchymotic hemorrhages on the mucous membranes. Many of these symptoms are referable to underlying thromboembolism and/or hemorrhagic episodes[19]. Spontaneous hemorrhage does not typically occur unless platelets are less than 50,000 and some dogs, buccal mucosal bleeding times may be normal.

Diagnosis is one of exclusion of underlying cause and treatment should be directed at addressing the underlying disease state which should be accurately assessed in order to maximize clinical response and survival.

Initial therapy is aimed at ameliorating the coagulopathy with use of intravenous fresh frozen plasma to replace lost thrombocytes and use of glucocorticoids at an immunosuppressive dose, cyclosporine, busulfan[20] or azathioprine.

The use of adjunct therapies such as lithium carbonate[21] or human intravenous immunoglobulin[22] have significantly reduced recovery times in some dogs and should be considered where financial constraints are not problematic.

References

  1. Pet Place
  2. Davenport DJ et al (1982) Platelet disorders in the dog and cat Part I: Physiology and Pathogenesis. J Cont Educ Pract Vet 4:762–772
  3. Grindem CB et al (1991) Epidemiologic survey of thrombocytopenia in dogs: a report on 987 cases. Vet Clin Path 20:38–43
  4. Gould SM & McInnes EL (1999) Immune-mediated thrombocytopenia associated with Angiostrongylus vasorum infection in a dog. Journal of Small Animal Practice 40:227–232
  5. O'neill E et al (2010) Immune-mediated thrombocytopenia associated with angiostrongylus vasorum infection in a Jack Russell terrier. Ir Vet J 63(7):434-440
  6. Cortese L et al (2009) Secondary immune-mediated thrombocytopenia in dogs naturally infected by Leishmania infantum. Vet Rec 164(25):778-782
  7. Giudice E et al (2010) Effect of desmopressin on immune-mediated haemorrhagic disorders due to canine monocytic ehrlichiosis: a preliminary study. J Vet Pharmacol Ther 33(6):610-614
  8. Scheepers E et al (2011) Serial haematology results in transfused and non-transfused dogs naturally infected with Babesia rossi. J S Afr Vet Assoc 82(3):136-143
  9. Cockwill KR et al (2009) Granulocytic anaplasmosis in three dogs from Saskatoon, Saskatchewan. Can Vet J 50:835–840
  10. Schnier LM (2010) A case of splenic torsion with progressive anemia and thrombocytopenia. Can Vet J 51(5):527-529
  11. Snead E et al (2011) Glucocorticoid-dependent hypoadrenocorticism with thrombocytopenia and neutropenia mimicking sepsis in a Labrador retriever dog. Can Vet J 52(10):1129-1134
  12. Botsch V et al (2009) Retrospective study of 871 dogs with thrombocytopenia. Vet Rec 164(21):647-651
  13. Brown MR & Rogers KS (2001) Neutropenia in dogs and cats: A retrospective study of 261 cases. J Am Anim Hosp Assoc 37:131–139
  14. Orcutt ES et al (2010) Immune-mediated hemolytic anemia and severe thrombocytopenia in dogs: 12 cases (2001-2008). J Vet Emerg Crit Care (San Antonio) 20(3):338-345
  15. Joshi BC & Jain NC (1977) Experimental immunologic thrombocytopenia in dogs: a study of thrombocytopenia and megakaryocytopoiesis. Res Vet Sci 22:11–17
  16. Trepanier LA et al (2003) Clinical findings in 40 dogs with hypersensitivity associated with administration of potentiated sulfonamides. J Vet Int Med 17:647–652
  17. Huang AA et al (2012) Idiopathic immune-mediated thrombocytopenia and recent vaccination in dogs. J Vet Intern Med 26(1):142-148
  18. Flatland B et al (2011) May-Hegglin anomaly in a dog. Vet Clin Pathol 40(2):207-214
  19. O'Marra SK et al (2012) Investigating hypercoagulability during treatment for immune-mediated thrombocytopenia: a pilot study. J Vet Emerg Crit Care (San Antonio) 22(1):126-130
  20. Mizukoshi T et al (2006) Essential thrombocythemia in a dog. J Vet Med Sci 68(11):1203-1206
  21. Leclerc A et al (2010) Effects of lithium carbonate on carboplatin-induced thrombocytopenia in dogs. Am J Vet Res 71(5):555-563
  22. Bianco D et al (2009) A prospective, randomized, double-blinded, placebo-controlled study of human intravenous immunoglobulin for the acute management of presumptive primary immune-mediated thrombocytopenia in dogs. J Vet Intern Med 23(5):1071-1078