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Abstract

Objective

To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry.

Animals

16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, ElAV-positive horses and ponies; and 2 thrombocytopenic, ElAV-negative horses.

Procedure

Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample of blood or platelet-rich plasma was incubated with thiazole orange, and flow cytometric analysis was performed. Percentage of circulating TO+ platelets was determined from fluorescence (FL-1) logarithmic histograms.

Results

Healthy ponies (n = 9) had 1.28 to 2.83% (mean ± SD, 2.03 ± 0.50%) and horses (n = 7) had 0.9 to 3.44% (2.12 ± 1.14%) TO+ platelets in circulation. Thrombocytopenic ponies (n = 7) had 11.14 to 48.41 % (26.51 ± 11.99%) and thrombocytopenic horses (n = 4) had 2.33 to 8.52% (6.19 ± 2.68%) TO+ platelets in circulation. Mean platelet counts for the thrombocytopenic ponies and horses were 24,400 ± 20,500 and 39,300 ± 13,500 platelets/μl, respectively (reference range, 94,000 to 232,000 platelets/μl).

Conclusion

Thiazole orange-positive platelets can be detected in equine blood and percentages of TO+ platelets are increased in thrombocytopenic horses.

Clinical Relevance

Enumeration of TO+ platelets may prove to be a helpful noninvasive clinical measurement of bone marrow platelet production and aid in the assessment of platelet kinetics in thrombocytopenic horses. (Am J Vet Res 1997;58:1092–1096)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To compare hematologic and serum biochemical variables and plasma ACTH concentration between healthy horses 5 to 12 years old and those more than 20 years old.

Animals

30 healthy horses 5 to 12 years old and 30 healthy horses more than 20 years old.

Procedures

Venous blood was collected from all horses, and CBC and serum biochemical analysis were performed for each horse. Plasma ACTH concentration was determined by radioimmunoassay. Student's paired t-test or the Mann-Whitney rank sum test was used to compare values between control and aged horse groups.

Results

Compared with values for control horses, aged horses had significantly higher erythrocyte mean cell volume and mean cell hemoglobin. Aged horses also had significantly decreased total lymphocyte count. Five aged horses had lymphocyte count that was lower than the low reference limit as established for horses in our laboratory. Differences between control and aged horses for serum biochemical or plasma ACTH values were not significant.

Conclusion

Compared with younger adult horses, those more than 20 years old have some hematologic differences, but there is no apparent effect of aging on baseline plasma ACTH concentration.

Clinical Relevance

It is important to establish age-matched control values for optimal interpretation of clinicopathologic variables. (Am J Vet Res 1998;59: 1247–1251)

Free access
in American Journal of Veterinary Research