[Thrombocytopenia in horses].

Area of Science:

• Veterinary Hematology
• Equine Internal Medicine
• Diagnostic Pathology

Background:

• Thrombocytopenia, a low platelet count, can be true or artifactual (e.g., EDTA-induced pseudothrombocytopenia).
• Accurate diagnosis is crucial for appropriate patient management and prognosis in horses.

Purpose of the Study:

• To determine the prevalence of true thrombocytopenia and EDTA-induced pseudothrombocytopenia in horses and ponies.
• To assess the diagnostic and prognostic significance of true thrombocytopenia in equine patients.

Main Methods:

• Retrospective review of hematological data from 3592 horses and ponies (2008-2015).
• Inclusion criteria: platelet counts < 90 x 10^9/L (EDTA-blood) or < 84 x 10^9/L (citrate blood).
• Classification of thrombocytopenia into true, EDTA-induced, and questionable categories; analysis of diagnoses and outcomes in true thrombocytopenia cases.

Main Results:

• Thrombocytopenia was identified in 3.4% of patients (123/3592).
• True thrombocytopenia accounted for 49% (60/123) of cases, with EDTA-induced pseudothrombocytopenia in 5% (6/123).
• Neoplasia was more frequent (18%) in true thrombocytopenia cases compared to the general clinic population (1%); mortality was 38% overall, with higher rates in inflammatory (32%) and neoplastic (82%) diseases.

Conclusions:

• True thrombocytopenia is rare in horses with internal medical conditions; citrate blood testing is recommended for verification.
• Thrombocytopenia is seldom the primary referral reason but serves as a negative prognostic indicator in horses with neoplastic and inflammatory conditions.