Extended sample storage for platelet function testing in healthy dogs

Abstract

Background: Platelet function testing is important for monitoring the effects of antiplatelet therapy but is not readily used due to time constraints for testing and the need for specialized equipment.Objectives: This study evaluated the effects of various storage methods on selected platelet function tests to determine if delayed platelet function testing is feasible in canine blood samples. Our hypotheses were that platelet function would not decline during storage and, thus, no differences in test results would be found over time.Methods: Thirteen healthy dogs were studied. Citrated blood samples were tested with a Platelet Function Analyzer-200 (PFA), which mimics high-shear conditions, using P2Y and CADP cartridges, after being held at room temperature for 2 h and refrigerated for 24 and 48 h. Plateletworks (PW), which measures aggregation based on platelet counting, was performed on an optical hematology analyzer using 10-min-old native samples, citrated samples held at room temperature for 3-4 h and refrigerated for 24 and 48 h, and samples stored in the preservative solution, AGGFix, up to 7 days.Results: PFA closure times increased with storage, especially with the P2Y cartridge.Median aggregation with fresh PW was 94%, and this was maintained at all time points (range of median values 88%-94%). Most samples showed decreased, yet still robust (>70%), aggregation with longer storage. Spontaneous aggregation in citrate was noted in most dogs. AGGFix stabilized platelet aggregates to allow for delayed testing.Conclusions: Delayed platelet function testing is feasible, but ranges of expected values may differ from tests using fresh samples.

Platelet function analyzer‐200 closure curve analysis and assessment of flow‐obstructed samples

“…This study only examined P2Y closure curves due to the small number of flow obstructions with paired data noted in COL/ADP samples. In general, COL/ADP is less likely to experience a flow obstruction than P2Y 7,10 ; however, it also does not detect the effect of clopidogrel in some samples where the effect is present on P2Y analysis. 3,7,21 The reason for this difference in flow obstruction is unclear, though factors increasing the sensitivity of the test may also contribute to an increased rate of flow obstruction; however, regardless of the cause, this association has anecdotally been noted by the authors.…”

“…These data included both feline patients treated with clopidogrel or suspected of having platelet function defects and healthy cats enrolled for research purposes in several previous studies. 10,11 All cats had blood samples collected from the jugular vein with 22 g needles. Samples were immediately transferred to 3.2% sodium citrate tubes (Becton Dickinson, Mississauga, ON, Canada).…”

“…3 While the PFA has been used in the diagnosis and monitoring of several human and veterinary platelet disorders 3,4 and for investigation of platelet function in cats with systemic disease, 5,6 a current primary role in veterinary medicine is to assess the effect of clopidogrel. [7][8][9][10][11][12] Two cartridges have been designed for this purpose; the COL/ ADP cartridge, which is compatible with both analyzers and the P2Y cartridge, which claims greater sensitivity and is only compatible with the PFA-200 and upgraded PFA-100. 7 Clopidogrel is recommended in cats as the first-line drug for the prevention and treatment of feline arterial thromboembolism, 13 and resistance to the effect of clopidogrel has been reported in 20% or more of treated cats.…”

Point‐of‐care platelet function testing results in a dog with Bernard–Soulier syndrome

“…Values for normal dogs have been reported for these cartridges. [13][14][15] F I G U R E 1 Platelet count (PLT), mean platelet volume (MPV), and plateletcrit (PCT) over time. PLT and MPV on the left axis, PCT on the right axis (Blue-PLT, Orange-MPV, and Gray-PCT).…”

“…Plateletworks is a test of platelet function based on the aggregation of platelets in response to an agonist. 13,15 It determines platelet function based on comparing platelet count in EDTA to platelet count in an agonist tube using an automated analyzer through the equation: % aggregation = (PLT EDTA-PLT Agonist)/PLT EDTA × 100.…”