Effects of in vitro hemodilution of canine blood on platelet function analysis using the PFA-100.
BACKGROUND
The platelet function analyzer (PFA)-100 is a point-of-care instrument previously evaluated in humans and dogs. In both species, artificially prolonged platelet closure time (CT) occurs with anemia. Reliability of the analyzer in dogs becomes a concern when the HCT is between 0.25 and 0.35 L/L.


OBJECTIVE
The objective of this study was to further define the level of HCT at which CT is prolonged, using in vitro diluted canine blood.


METHODS
Citrated whole blood samples were collected from 22 healthy dogs. Initial HCT was determined and autologous platelet-rich plasma was added to samples to achieve HCTs of 0.33, 0.30, and 0.27 L/L. CT was determined in duplicate on the PFA-100 using collagen/adenosine-5'-diphosphate cartridges.


RESULTS
Compared with the initial CT in samples with HCT 0.39-0.54 L/L (CT mean+/-SD=57.8+/-5.75 seconds), significantly prolonged CTs were found in hemodiluted samples with HCT 0.33 L/L (61.1+/-4.64 seconds), 0.30 L/L (64.3+/-6.79 seconds), and 0.27 L/L (70.8+/-7.90 seconds) (P=0.029; repeated measures ANOVA).


CONCLUSIONS
Although statistical differences were found, further studies are needed to determine the clinical significance of the mild prolongation in CT associated with mild anemia. Until then, dogs with HCTs slightly <0.35 L/L should be evaluated cautiously for platelet dysfunction using the PFA-100.
Clancey
Noel
N
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada. nclancey@groupwise.upei.ca
Burton
Shelley
S
Horney
Barbara
B
Mackenzie
Allan
A
Nicastro
Andrea
A
Côté
Etienne
E
D000818:Animals; D004285:Dogs / Q000097:blood*; D005260:Female; D006438:Hemodilution / Q000662:veterinary*; D008297:Male; D010979:Platelet Function Tests / Q000295:instrumentation / Q000662:veterinary*