No abstract

Background: Cardiac disease has the potential to alter platelet function in dogs. Evaluation of platelet function using the PFA-100 analyzer in dogs of multiple breeds and with a broad range of cardiac conditions would help clarify the effect of cardiac disease on platelets. Objectives: The objective of this study was to assess differences in closure time (CT) in dogs with cardiac disease associated with murmurs, when compared with that of healthy dogs. Methods: Thirty-nine dogs with cardiac murmurs and turbulent blood flow as determined echocardiographically were included in the study. The dogs represented 23 different breeds. Dogs with murmurs were further divided into those with atrioventricular valvular insufficiency (n = 23) and subaortic stenosis (n = 9). Fifty-eight clinically healthy dogs were used as controls. CTs were determined in duplicate on a PFA-100 analyzer using collagen/ ADP cartridges. Results: Compared with CTs in the control group (mean AE SD, 57.6 AE 5.9 seconds; median, 56.5 seconds; reference interval, 48.0-77.0 seconds), dogs with valvular insufficiency (mean AE SD, 81.9 AE 26.3 seconds; median, 78.0 seconds; range, 52.5-187 seconds), subaortic stenosis (71.4 AE 16.5 seconds; median, 66.0 seconds; range, 51.5-95.0 seconds), and all dogs with murmurs combined (79.6 AE 24.1 seconds; median, 74.0 seconds; range, 48.0-187 seconds) had significantly prolonged CTs (P o.01). Conclusions: The PFA-100 analyzer is useful in detecting platelet function defects in dogs with cardiac murmurs, most notably those caused by mitral and/or tricuspid valvular insufficiency or subaortic stenosis. The form of turbulent blood flow does not appear to be an important factor in platelet hypofunction in these forms of cardiac disease.

Background Fine‐needle aspiration (FNA) is a common procedure as a diagnostic tool in veterinary medicine. However, it is unclear whether the gauge of the needle affects the quality of cytology. Objective This study compared the quality of cytologic samples obtained via FNA using 22‐ or 25‐gauge needles. Methods Fine‐needle aspiration was performed on 50 masses (cutaneous, subcutaneous, or intracavitary) obtained from client‐owned animals. The size of the needle was randomly assigned using either of the following two sequences: 22‐25‐22 gauge or 25‐22‐25 gauge. Samples were evaluated by two board‐certified clinical pathologists to assess cellularity, blood contamination, amount of cellular debris, degree of cellular trauma, and the overall ability to make a diagnosis for each sample. Results No significant difference was detected between the 22‐ and 25‐gauge needle samples for cellularity, whereas a significant difference was present for blood contamination, amount of cellular debris, and degree of cellular trauma. The overall ability to make a diagnosis was not significantly affected by the needle gauge. The degree of cellular trauma was significantly increased in intracavitary samples. Conclusions and Clinical Relevance Needle gauge is a contributing factor to FNA sample quality. However, it did not affect the overall ability to make a diagnosis. Samples obtained using 25‐gauge needles resulted in less blood contamination yet increased cellular trauma compared to 22‐gauge needle samples.

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 0-diphosphate cartridges. Results: Compared with the initial CT in samples with HCT 0.39-0.54 L/L (CT mean AE SD = 57.8 AE 5.75 seconds), significantly prolonged CTs were found in hemodiluted samples with HCT 0.33 L/L (61.1 AE 4.64 seconds), 0.30 L/L (64.3 AE 6.79 seconds), and 0.27 L/L (70.8 AE 7.90 seconds) (P = 0.029; repeated measures ANOVA). Conclusion: 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 o 0.35 L/L should be evaluated cautiously for platelet dysfunction using the PFA-100. Platelets play a vital role in hemostasis. Dogs experience a variety of serious conditions potentially involving increased or decreased platelet function. 1-6 Assessment of platelet hypofunction and hyperfunction involves sophisticated testing including flow cytometry and platelet aggregation. These techniques are not routinely available in diagnostic laboratories, are labor intensive, and require specialized training. The development of a simple point-of-care instrument, the platelet function ana-lyzer (PFA-100), 7-9 has allowed identification of human platelet hyperfunction 10,11 and hypofunction. 12,13 The PFA-100 is easy to use and has been investigated and validated for use in dogs. 14-16 Other than unreliable results when thrombocytopenia is present, the main drawback of using the PFA-100 is that anemia prolongs the time to formation of a platelet plug, the closure time (CT). This has been demonstrated in humans 17,18 and in dogs. 16,19 Anemia is believed to result in decreased CT due to rheo-logical alterations in the sample 20 and because the lower number of RBCs provides less physical stimulus for plate-let arachidonic acid release. 21 Manufacturer guidelines for human samples indicate that an increased CT may be seen in samples with HCT o 0.35 L/L. 22 This effect has been only minimally investigated in dogs, using small sample sizes 16,19 and at specific in vitro HCTs of 0.15, 0.25, and 0.35 L/L, without evaluation of values in-between these levels. 23 In the latter study, CTs in samples from 10 dogs were significantly prolonged at a HCT of 0.25 L/L, but not 0.35 L/L, compared with an initial mean HCT of 0.58 L/L. 23 As the range between 0.25 and 0....

In collaboration with the American College of Veterinary Pathologists

An 11-year-old castrated male mixed breed dog presented for evaluation of a 4 cm diameter, movable, subcutaneous, left ventrolateral cervical mass. Physical examination was otherwise unremarkable, and no abnormalities were present on a complete blood count and a serum biochemistry profile. Fine-needle aspirate preparations were submitted (Figure 1).

Background: As hyperkalemia may be life-threatening, it is critical to recognize artifactually increased potassium concentrations. Pseudohyperkalemia may occur in myopathies when using the VetScan2 analyzer (VS2), but the degree of pseudohyperkalemia and relationships relative to creatine kinase activity (CK) are unknown.

Blood smear evaluation is an important component of a complete blood count (CBC). Blood smear preparation and CBC data attainment are best performed on freshly collected potassium ethylene diamine tetra-acetic acid (K 3 -EDTA) anticoagulated whole blood samples. This is because delays may cause age-related deterioration and morphologic changes in erythrocytes, leukocytes, and platelets. [1][2][3][4][5][6] Cellular deterioration in aged samples negatively impacts hematologic parameters, including hematocrit, mean corpuscular