Presumed primary immune-mediated thrombocytopenia in four cats

ACVIM consensus statement on the treatment of immune thrombocytopenia in dogs and cats

Management of immune thrombocytopenia (ITP) in dogs and cats is evolving, but there are no evidence-based guidelines to assist clinicians with treatment decisions. Likewise, the overall goals for treatment of ITP have not been established. Immunosuppressive doses of glucocorticoids are the first line treatment, but optimal treatment regimens beyond glucocorticoids remain uncertain. Additional options include secondary immunosuppressive drugs such as azathioprine, modified cyclosporine, and mycophenolate mofetil, usually selected based on clinician preference. Vincristine, human IV immunoglobulin (hIVIg), and transfusion of platelet or red blood cell-containing products are often used in more severe cases. Splenectomy and thrombopoietin receptor agonists are usually reserved for refractory cases, but when and in which patient these modalities should be employed is under debate. To develop evidence-based guidelines for individualized treatment of ITP patients, we asked 20 Population Intervention Comparison Outcome (PICO) format questions. These were addressed by 17 evidence evaluators using a literature pool of 288 articles identified by a structured search strategy. Evidence evaluators, using panel-designed templates and data extraction tools, summarized evidence and created guideline recommendations. These were integrated by treatment domain chairs and then refined by iterative Delphi survey review to reach consensus on the final guidelines. In addition, 19 non-PICO questions covering scenarios in which evidence was lacking or of low quality were answered by expert opinion using iterative Delphi surveys with panelist integration and refinement. Commentary was solicited from multiple relevant professional organizations before finalizing the consensus. The rigorous consensus process identified few comparative treatment studies, highlighting many areas of ITP treatment requiring additional studies. This statement is a companion manuscript to the ACVIM Consensus Statement on the Diagnosis of Immune Thrombocytopenia in Dogs and Cats.

Prevalence and disease associations in feline thrombocytopenia: a retrospective study of 194 cases

OBJECTIVES

To assess the prevalence of thrombocytopenia in a referral population of cats in the UK, to identify disease processes associated with thrombocytopenia and to assess the proportion of thrombocytopenic cats that tested positive for feline leukaemia virus or feline immunodeficiency virus.

MATERIALS AND METHODS

Retrospective analysis of medical records at a UK referral hospital. Cats were grouped by mechanism of thrombocytopenia and disease process (where known).

RESULTS

Prevalence of thrombocytopenia was 5·9%. The most common disease processes associated with thrombocytopenia were haematological or infectious disease and neoplasia; 11% of thrombocytopenic cats tested were positive for feline leukaemia virus, which is lower than reported previously. Cats presenting with unexplained haemorrhage had significantly lower platelet counts than other thrombocytopenic cats. Primary immune-mediated thrombocytopenia was less commonly diagnosed than in dogs and associated with the most severe platelet depletion in this study.

CLINICAL SIGNIFICANCE

Thrombocytopenia in cats may be more prevalent than previously reported and severe thrombocytopenia may be associated with spontaneous haemorrhage. Severe thrombocytopenia in cats appears less commonly immune-mediated than in dogs. Thrombocytopenia did not appear to be associated with retroviral infections.

Primary immune-mediated thrombocytopenia and immune-mediated neutropenia suspected in a 21-week-old Maine Coon cat

CASE REPORT

A 21-week-old Maine Coon cat presented with an acute-onset coagulopathy. Severe concurrent thrombocytopenia and neutropenia were identified on peripheral blood smears and bone marrow cytology supported a peripheral consumptive process. Other than mild superficial haemorrhage, the cat was clinically well and screening for retroviral diseases, abdominal ultrasound examination, thoracic radiography, haematology and biochemistry panels did not identify an underlying disease. There was no historical pharmaceutical or toxicological trigger noted and the cat was from an area without endemic Ehrlichia spp. There was a rapid resolution of both cytopenias following treatment with immunosuppressive doses of prednisolone, though a mild relapse occurred during gradual prednisolone withdrawal and was responsive to a dose increase.

CONCLUSIONS

This report describes this combination of diseases for the first time in a cat and presents a younger patient than previously described with feline primary immune-mediated haematological disease.

Primary Immune-Mediated Thrombocytopenia in Cats

Feline primary immune-mediated thrombocytopenia (pIMT) is a rare condition, and only a few cases have been described in veterinary literature. Five cats with severe thrombocytopenia most likely due to pIMT are described. A flow cytometry platelet-bound antibody test was positive in all cats; underlying diseases or triggering factors causing thrombocytopenia were not detected. Three cats were transfused with blood type-compatible fresh whole blood; one cat received Oxyglobin as well. All cats were treated with prednisolone; one cat received chlorambucil in addition. Four cats responded to treatment and were discharged from the hospital. One cat was euthanized due to dyspnea. Primary immune-mediated thrombocytopenia is rarely diagnosed in cats, but it is important as a differential diagnosis in cats presented with surface bleeding.