Comparison of hematologic values and transforming growth factor-beta and insulin-like growth factor concentrations in platelet concentrates obtained by use of buffy coat and apheresis methods from equine blood

OBJECTIVE: To evaluate the buffy coat and apheresis methods for preparation of platelet concentrates from equine blood by comparing platelet and growth factor concentrations. ANIMALS: 15 mature mixed-breed geldings. PROCEDURE: Whole blood samples were collected and processed by use of a buffy coat or apheresis method to obtain platelet poor and platelet concentrated fractions. The PCV, WBC count, and platelet count were compared among whole blood samples, platelet poor fractions, concentrates obtained by use of the apheresis method (ie, apheresis platelet concentrates), and concentrates obtained by use of the buffy coat method (ie, buffy coat platelet concentrates). Concentrations of transforming growth factor-beta (ie,TGF-beta1 andTGF-beta2) and insulin-like growth factor were compared between buffy coat and apheresis platelet concentrates. RESULTS: Platelet concentrations were 8.9-fold and 5.2-fold greater in buffy coat and apheresis platelet concentrates, respectively, compared with whole blood. Platelet concentrations were 13.1-fold greater in filtered apheresis platelet concentrates, compared with whole blood. TGF-beta1 concentrations were 2.8-fold and 3.1-fold greater in buffy coat and apheresis platelet concentrates, respectively, and TGF-beta1 concentrations were 10.5-fold greater in filtered apheresis platelet concentrates, compared with whole blood. TGF-beta2 concentrations were 3.6-fold greater in apheresis platelet concentrates, compared with whole blood. Platelet concentrations correlated with growth factor concentrations across all blood and platelet fractions. White blood cell counts had a significant positive correlation with TGF-beta1 concentration in buffy coat platelet concentrates. CONCLUSIONS AND CLINICAL RELEVANCE: Platelets and TGF-beta1 can be concentrated reliably from equine blood by use of buffy coat or apheresis methods, without modification of the protocols used for humans.     

Comparison of methods for determining platelet numbers and volume in Cavalier King Charles spaniels

OBJECTIVE: The purpose of this study was to compare platelet concentration in cavalier King Charles spaniels (CKCS) measured by different methods commonly used in veterinary hospitals and commercial laboratories. METHODS: Blood samples obtained from 41 CKCS [corrected] were analysed by impedance cell counter, laser cell counter and microscopic estimation. Quantitative buffy coat analysis was performed only on 17 samples, selected from CKCS [corrected] that had low platelet counts detected by cell counters. Platelet counts, platelet estimations and platelet parameters using these different methods were compared. RESULTS: The median platelet number was lower when estimated using impedance cell counter (1363x10(9)/I) with respect to laser cell counter (1723x10(9)/I), microscopic estimation (238x10(9)/I) [corrected] or quantitative buffy coat analyser (292x10(9)/I) [corrected] (P<0.01). Although impedance cell counter, laser cell counter and microscopic estimation were positively correlated, there was no acceptable agreement among methods. CKCS [corrected] with macrothrombocytes in blood smears had significantly lower counts on impedance cell counter, laser cell counter and microscopic estimation. The percentages of CKCS [corrected] with platelet count < 100x10(9)/I [corrected] were 34.1 per cent (impedance cell counter), 26.8 per cent (laser cell counter), 22.0 per cent (microscopic estimation) (not statistically different) and 5.8 per cent (quantitative buffy coat analyser) (P<0.05). CLINICAL SIGNIFICANCE: CKCS [corrected] with macrothrombocytosis have low platelet counts on impedance cell counters, laser cell counters and microscopic estimation. CKCS [corrected] with low platelet counts may have a normal platelet crit detected by a quantitative buffy coat analyser and thus a normal circulating platelet mass.     

Vortex mixing of feline blood to disaggregate platelet clumps

Abstract: Platelet clumping is a common cause of erroneous platelet counts in cats. Mixing of blood with a vortex mixer was evaluated as a method to disaggregate platelet clumps in feline blood and thus obtain accurate platelet counts. Whole blood samples from 42 cats with platelet clumping and 10 control cats without platelet clumping were mixed for 1 minute at the maximal setting using a standard vortex mixer. Blood smears (for subjective assessment of the type and amount of platelet clumping), platelet counts, and total leukocyte counts were evaluated before and after mixing. Vortex treatment of blood samples with platelet clumps caused an increased platelet count in all but 1 sample. Although most samples had strong increases in platelet counts after mixing, only a minority of samples (5 of 42) appeared to have all platelet clumps dispersed. Of 39 feline blood samples with platelet counts initially <200×10⁹ cells/L, 23 counts increased to >200×10⁹ cells/L and 34 counts increased to >100×10⁹ cells/L. Overall, mixing gave inconsistent and partial improvement in platelet counts. Total leukocyte counts were not significantly affected by vortex mixing. Vortex mixing of 10 feline blood samples without platelet clumping had no consistent effect on platelet or WBC counts. In conclusion, vortex mixing of feline blood does not appear to be a consistent means of correcting the problem of feline platelet clumping.     

Platelet concentrations and platelet-associated IgG in greyhounds

BACKGROUND: Greyhounds have lower platelet concentrations (PC) than dogs of other breeds have. No underlying cause has been investigated. HYPOTHESIS: We hypothesized that Greyhounds have lower mean PC because of breed variation, not immune-mediated causes. Our secondary hypothesis was that PC is dependent on the method of analysis. ANIMALS: Sixty privately owned Greyhounds in Kansas. METHODS: Blood samples were collected into evacuated glass tubes containing ethylenediamine tetraacetic acid (EDTA). Blood smears were evaluated for platelet clumps. All 60 samples had PC determined by manual, impedance, and buffy coat analyzer methods. Results of the 60 samples were compared with results of samples with (n = 25) and without (n = 35) clumps, and with control dogs. Platelets were assayed for the presence of surface-associated antigen (PSAIgG) by direct immunofluorescence. RESULTS: The mean PC was below that of the control dogs for the impedance method (P < .001). No significant difference in PC was detected between analysis methods or between samples with or without platelet clumps. Three of 60 (5%) of the Greyhounds had PC between 50,000 and 100,000/microL with impedance analysis; no samples had < 100,000/microL via buffy coat analysis. PSAIgG was not identified in any samples. CONCLUSIONS AND CLINICAL IMPORTANCE: The mean Greyhound PC for the impedance method was below the reference interval for control dogs but was not significantly different from PC determined by other methods. An immune-mediated cause for the lower PC was unlikely because no samples had PSAIgG. The decreased PC is most consistent with breed variation. As only 0-5% of samples, depending on analysis method, had PC < 100,000/microL, a Greyhound with a PC < 100,000/microL is not necessarily consistent with breed variation, thus diagnostic testing is indicated.     

A comparison of platelet parameters in EDTA- and citrate-anticoagulated blood in dogs

BACKGROUND: Platelet aggregates are a common artifact in canine blood. Aggregates may affect the accuracy of platelet counts, with important consequences for patient care. OBJECTIVES: The purpose of this study was to determine if platelet counts in dogs were more accurate if blood was collected into citrate instead of EDTA as an anticoagulant. METHODS: Blood was collected from 50 dogs with neoplasia admitted to the oncology service at Cornell University. EDTA and citrate Vacutainer tubes were filled with blood in random order. Platelet counts and parameters (mean platelet volume [MPV], platelet distribution width [PDW], mean platelet component concentration [MPC], platelet component distribution width [PCDW], and automated platelet clump count [APCC]) were determined using an optical-based hematology analyzer (ADVIA 120). Blood smears from each anticoagulated sample were scored visually for platelet aggregates. RESULTS: The median platelet count was significantly lower (median decrease, 27 x 10(9)/L) in citrate-anticoagulated blood compared with EDTA-anticoagulated blood. This was attributed to platelet activation and aggregation: significantly more aggregates were seen in smears of citrate- than of EDTA-anticoagulated blood. Aggregates were typically small and not detected by the analyzer. Also, the MPV and MPC (or density) were significantly higher (median increase, 3 fL) and lower (median decrease, 33 g/L) in citrate-anticoagulated samples, respectively. CONCLUSIONS: Platelets aggregate, likely from activation, when blood from dogs with neoplasia is anticoagulated with citrate for hematology testing, resulting in lower platelet counts. Citrate also yields inaccurate results for MPV and MPC, likely because of inadequate sphering of platelets. Thus, we recommend that citrate not be used as an anticoagulant when accurate platelet counts are desired in dogs.     

Estimation of platelet counts on feline blood smears

Blood samples were obtained from 50 cats admitted for hematologic evaluation at the Royal (Dick) School of Veterinary Studies. Manual platelet counts were done using a hemacytometer, and the average number of platelets per oil immersion field (1,000X magnification) was determined on stained blood smears. A hemacytometer count was not obtained for one sample because of a failure in erythrocyte lysing. In nine samples, obvious platelet clumps in the blood smear prevented accurate determination of the number of platelets per oil immersion field. Hemacytometer counts on these nine samples ranged from 260-587 X 10 (3) platelets/microliter, suggesting that platelet clumps on a blood smear were usually associated with adequate platelet numbers. Simple regression analysis of hemacytometer counts and the average umber of platelets per oil immersion field for the remaining 40 samples yielded correlation coefficients (r) of 0.776 on untransformed data, and 0.892 on log10-transformed data. Each platelet per oil immersion field represented a circulating platelet count of approximately 20 X 10(3)/microliter, similar to conversion factors reported for dogs and human beings. It was concluded that estimation of platelet number on stained blood smears is a simple and quick method that appears to be reliable over a wide range of platelet counts in cats.     

Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation

Abstract: True thrombocytopenia is uncommon in cats; however, low platelet counts frequently are found using automated cell counters. Although this discrepancy is a well known problem, the prevalence of low automated platelet counts in feline blood samples has not been documented. We retrospectively compared the prevalence of low automated platelet counts with low blood smear-estimated platelet counts in feline blood samples. Results of blood sample analysis from 359 cats during a 1-year period at the University of Glasgow Veterinary Haematology Laboratory were examined. Smear estimates of platelet number were done in those cases in which records did not indicate adequate platelet numbers. Platelet counts obtained with an impedance counter (Minos Vet, Abx Hematologie) were <200×10⁹ cells/L in 256 samples (71%) and <50×10⁹ cells/L in 43 samples (12%). However, based on estimation of platelet numbers from blood smears, only 11 samples (3.1%) had platelet counts of <200×10⁹ cells/L and 9 samples (2.5%) had counts of <50×10⁹ cells/L. Four cats with thrombocytopenia estimated by blood smear evaluation had clinical signs of a bleeding disorder. Disorders associated with thrombocytopenia included neoplasia, cytotoxic chemotherapy, and infectious diseases. There was no evidence that delay due to mailing of samples was associated with lower automated platelet counts than would have been obtained on the day of sampling. The high prevalence of apparent thrombocytopenia in automated platelet counts was attributed to a combination of platelet aggregation and the impedance method of cell differentiation by size. Vigilance and careful examination of blood smears is required to identify the few cats with true thrombocytopenia.     

Quantitative buffy coat analysis of blood collected from dogs, cats, and horses

Using quantitative buffy coat analysis (QBCA), rapid and accurate measurements can be made of the erythrocyte PCV, total WBC count, and platelet count, and the leukocyte population can be differentiated into total granulocytes (including quantitation of eosinophils), and lymphocytes and monocytes. The QBCA is performed by placing a blood sample (50 to 111 microliters) into a high-precision-bore microhematocrit tube that contains a freely moving, closely fitting, cylindrical plastic float. After centrifugation for 5 minutes, the buffy coat components separate by density. The plastic cylinder floats in the buffy coat, thereby expanding the lengths of the buffy coat layers. The layers are measured in a manner that is similar to that used for measuring PCV. Results of QBCA of blood samples from dogs, cats, and horses indicated that the hematologic values obtained correlated with results obtained by use of conventional methods. The accuracy and ease of use of QBCA and the availability of results while the animal is still being examined make QBCA a useful tool for hematologic evaluation of animals.     

Evaluation of methods of platelet counting in the cat

Platelet counts were performed in 50 cats presented for diagnostic investigation. For each cat, counts were obtained using a manual haemocytometer method and compared with counts obtained by estimation from a stained blood smear, a QBC VetAutoread analyser, a Zynocyte VS/2000 analyser, impedance automated counts on a Baker System using both EDTA and citrated anticoagulated blood, and use of a Zynostain modified counting chamber kit. None of the methods gave high correlation with the haemocytometer counts. The blood smear estimation of platelet counts had the highest correlation (r = 0.776) and was the only method to have reasonable values for both sensitivity and specificity. With the impedance automated counts, citrated anticoagulated blood had marginally higher correlation than EDTA anticoagulated blood, and the time between blood sampling and platelet count determination had no effect on the count obtained. When in-house analyser or impedance automated platelet counts are abnormal or not consistent with clinical findings, the authors recommend that a manual platelet count using either haemocytometry or examination of a blood smear is performed.     

Frequency and severity of mastocytemia in dogs with and without mast cell tumors: 120 cases (1995-1997).

OBJECTIVE: To elucidate frequency of detection on blood smears and severity on quantitative buffy coat evaluation of mastocytemia between dogs without mast cell tumors (MCT) and dogs that had MCT, and to expand the list of diseases associated with mastocytemia in dogs without MCT. DESIGN: Retrospective study. ANIMALS: 94 dogs without MCT and 26 dogs with MCT. PROCEDURE: Medical records of all dogs with mast cells detected on blood or buffy coat smears during a 2-year period were reviewed. Dogs with mastocytemia were grouped by disease into dogs with MCT and dogs without MCT. Twenty-five of the dogs without MCT that had mast cells detected on blood smears also had evaluations of buffy coat smears. Quantitative buffy coat results of the 25 dogs without MCT were compared with those of the 26 dogs with MCT. RESULTS: 95.5% of blood smears with mast cells detected during CBC determination were from dogs without MCT. For these dogs, diagnoses included inflammatory disease (28.2%), regenerative anemia (27%), neoplasia other than MCT (25.9%), and trauma (11.8%). Dogs with MCT had a mean of 71.4 mast cells/buffy coat smear, whereas dogs without MCT had a mean of 276.2 mast cells/buffy coat smear. The 2 highest counts of mast cells/buffy coat smear were for dogs without MCT. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of results of quantitative buffy coat evaluations, severity of mastocytemia in dogs without MCT often exceeds that detected during tumor staging in dogs with MCT. Random detection of mast cells in blood smears during CBC determination in dogs is usually not secondary to MCT.     

Immunofluorescence of bovine virus diarrhea viral antigen in white blood cells from experimentally infected immunocompetent calves.

A study to evaluate the detection of bovine virus diarrhea viral antigen using immunofluorescence testing of white blood cells was conducted. Five colostrum-deprived calves were inoculated intravenously with a cytopathic strain of the virus. Lymphocyte and buffy coat smears were prepared daily for direct immunofluorescent staining for detection of antigen. Lymphocytes were separated from heparinized blood using a Ficoll density procedure. Buffy coat smears were prepared from centrifuged blood samples collected using ethylenediaminetetraacetic acid as an anticoagulant. Bovine viral diarrhea virus antigen was detected by immunofluorescence between 3 and 11 days postinfection in lymphocyte smears and 3 to 12 days postinfection in buffy coat smears. Isolation of virus from both lymphocytes and buffy coat preparations correlated with detection of immunofluorescence. Serum neutralizing antibody to bovine virus diarrhea virus was detected on day 10 postinfection. Buffy coat smears were as sensitive as lymphocyte smears for the detection of antigen by immunofluorescence. It appeared that immunofluorescent staining of white blood cells was an effective method of detecting bovine virus diarrhea viral antigen.     

Determination of the number of mast cells in lymph node, bone marrow, and buffy coat cytologic specimens from dogs.

Cytologic samples of popliteal lymph node, proximal femoral bone marrow, and the buffy coat fraction of blood were obtained from 56 dogs. The number of mast cells on 1 slide of each sample was determined by microscopic examination. Eleven of 46 slides of lymph node aspirate contained mast cells (range, 1 to 16; mean, 6.4; median, 5 mast cells/slide). Fifty-one bone marrow aspirate slides were evaluated. Two of these contained a single mast cell. None of the 53 buffy coat smear slides examined contained any mast cells. These results indicated that in clinically normal dogs, a few to several mast cells may be encountered in smears of lymph node aspirate, mast cells are rare in smears of bone marrow aspirate, and mast cells are absent from smears of buffy coat.     

Evaluation of platelet count and its association with plateletcrit, mean platelet volume, and platelet size distribution width in a canine model of endotoxemia

BACKGROUND: Platelets are of great importance in the pathogenesis of endotoxemia. Although thrombocytopenia is used as a diagnostic sign of endotoxemia, changes in values for platelet indices (plateletcrit [PCT], mean platelet volume [MPV], and platelet size distribution width [PDW]) in response to endotoxin are still unknown. OBJECTIVE: The aim of this study was to evaluate platelet count and its relations with platelet indices in a canine model of endotoxemia. Methods: Twenty dogs were divided into 2 groups of 10 each, and treated intravenously with Escherichia coli endotoxin (1 mg/kg) or vehicle. Venous blood samples were collected before treatment (0 hour) and 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after treatment. Platelet counts and indices were determined on a CELL-DYN hematology analyzer. RESULTS: The platelet count and PCT decreased by a mean of 73% and 93%, respectively (P<.001), at 0.5 hour, and remained 70% and 85% lower than baseline values (P<.001) for 24 hours after endotoxin injection. MPV and PDW increased by a mean of 28% and 45%, respectively (P<.01), at 0.5 hour, and remained increased by 7% and 16% over baseline values for 24 hours (P<.01-.001). Platelet count correlated positively with PCT (P<.001), but correlated negatively with MPV (P<.001) and PDW (P<.01). CONCLUSIONS: Changes in platelet count and its association with platelet indices may reflect changes in platelet production and reactivity. Platelet indices have potential value in the diagnosis and monitoring of dogs and humans with endotoxemia.     

A Simple Method for Separation of Buffy Coat from Peripheral Blood of Chickens

A simple pasteur pipette tube technique is described for the separation of buffy coat from the peripheral blood of chickens. Whole blood treated with disodium ethylenediaminetetraacetate (EDTA) and/or heparin is centrifuged. The buffy coat is removed by aspiration, resuspended in plasma and recentrifuged in tubes made from pasteur pipettes. From such narrow columns buffy coat suspensions may be recovered virtually free of red blood cells (<6 per cent).

The recovery of nongranular leukocytes from EDTA-treated and heparin + EDTA-treated blood samples was 44.1 and 39.8 per cent respectively. The preparations obtained by both methods still contained high concentrations of thrombocytes. On an average, EDTA-treated and heparin + EDTA-treated preparations contained 230.3 and 58.4 thrombocytes per 100 leukocytes respectively. The recovery of thrombocytes in EDTA-treated preparations amounted to 42.7 per cent so that this technique may be used to concentrate thrombocytes for further study. The separation of buffy coat with heparin alone was not as clear and consistent because of the cell clumping which occurred.

     

Feline platelet counting with prostaglandin E1 on the Sysmex XT‐2000iV

Background: The large size of many feline platelets and the high frequency of platelet aggregation often results in falsely low platelet counts in this species. A combination of optical platelet counting to detect even large platelets and the use of prostaglandin E1 (PGE1) to inhibit platelet clumping may increase the accuracy of feline platelet counting. Objective: The objective of this study was to compare platelet counts in feline whole blood samples with and without the addition of PGE1 and using different analytical methods in a clinical setting. Methods: Platelet counts were determined in 10 feline patients in a referral veterinary hospital using 2 sample types (EDTA, EDTA with PGE1) and 2 methods of analysis (optical counting [PLT‐O] and impedance counting [PLT‐I]) on the Sysmex XT 2000 iV analyzer. Results: All PGE1–PLT‐O samples had platelet counts of >200 × 10⁹/L. Mean platelet count using PGE1–PLT‐O (410,256±178 × 10⁹/L) was significantly higher (P<.03) compared with PGE1–PLT‐I (256±113 × 10⁹/L), EDTA–PLT‐O (238±107 × 10⁹/L), and EDTA–PLT‐I (142±84 × 10⁹/L) methods. Depending on the method, platelet counts in 2 to 7 of 10 cats were <200 × 10⁹/L when PGE1‐PLT‐O was not used. A slightly increased platelet count in response to treatment of a feline patient with thrombocytopenia would have been missed without use of PGE1–PLT‐O. Conclusions: Using PLT‐O analysis on EDTA samples containing PGE1 provides higher, and therefore likely more accurate, feline platelet counts in a clinical setting.     

Plateletcrit is superior to platelet count for assessing platelet status in Cavalier King Charles Spaniels

Background: Many Cavalier King Charles Spaniel (CKCS) dogs are affected by an autosomal recessive dysplasia of platelets resulting in fewer but larger platelets. The IDEXX Vet Autoread (QBC) hematology analyzer directly measures the relative volume of platelets in a blood sample (plateletcrit). We hypothesized that CKCS both with and without hereditary macrothrombocytosis would have a normal plateletcrit and that the QBC results would better identify the total circulating volume of platelets in CKSC than methods directly enumerating platelet numbers.
Objectives: The major purpose of this study was to compare the QBC platelet results with platelet counts from other automated and manual methods for evaluating platelet status in CKCS dogs.
Methods: Platelet counts were determined in fresh EDTA blood from 27 adult CKCS dogs using the QBC, Sysmex XT-2000iV (optical and impedance), CELL-DYN 3500, blood smear estimate, and manual methods. Sysmex optical platelet counts were reanalyzed following gating to determine the number and percentage of normal- and large-sized platelets in each blood sample.
Results: None of the 27 CKCS dogs had thrombocytopenia (defined as <164 × 10⁹ platelets/L) based on the QBC platelet count. Fourteen (52%) to 18 (66%) of the dogs had thrombocytopenia with other methods. The percentage of large platelets, as determined by regating the Sysmex optical platelet counts, ranged from 1% to 75%, in a gradual continuum.
Conclusions: The QBC may be the best analyzer for assessing clinically relevant thrombocytopenia in CKCS dogs, because its platelet count is based on the plateletcrit, a measurement of platelet mass.     

Evaluation of a citrate-based anticoagulant with platelet inhibitory activity for feline blood cell Counts

Abstract: Aggregation of feline platelets in vitro results in difficulty assessing platelet number. A citrate-based anticoagulant containing the platelet inhibitors theophylline, adenosine, and dipyridamole (CTAD; Diatube-H, Becton Dickinson, Oxford, UK) has been developed for use in human platelet studies and heparin assays. To evaluate the efficacy of CTAD in reducing platelet aggregation in feline blood samples, aliquots of blood from 51 cats were anticoagulated with EDTA, CTAD, and for 12 samples, citrate solution. Samples preserved in CTAD had significantly higher (P ≤ .001) platelet counts, as determined by an impedance counter, hemacy-tometer, and smear estimation, than samples preserved in EDTA. In addition, subjective assessment of blood smears showed significantly fewer platelet aggregates (P<.001) in CTAD-treated samples compared with EDTA samples. Although values were similar, automated platelet counts and smear estimates of platelet number were significantly higher (P < .05) and platelet aggregation was significantly less (P < .05) in CTAD samples than in citrate samples. These results suggest that the platelet inhibitory activity of CTAD reduced feline platelet aggregation. Automated total WBC counts in CTAD samples were significantly lower (P<.001) than automated counts in EDTA samples but were similar to manual WBC counts in EDTA samples. Differences in both platelet and WBC counts between CTAD and EDTA or citrate samples were clinically relevant. Mean platelet volume and MCV were significantly lower (P< .05) in CTAD samples than in EDTA samples. No effect was seen on cell morphology or staining characteristics. The anticoagulant CTAD offers an advantage over both EDTA and citrate for feline hematologic analysis, by decreasing pseudothrombocytopenia and pseudoleukocytosis.     

Effects of low-dose aspirin and specific thromboxane synthetase inhibition on whole blood platelet aggregation and adenosine triphosphate secretion in healthy dogs.

Platelet aggregation and adenosine triphosphate (ATP) secretion in response to arachidonic acid (10 microM) or collagen (5 micrograms/ml) were compared in healthy, adult female Beagles treated with low-dosage aspirin (3.5 mg/kg of body weight, PO, q 12 h for 7 treatments) or with CGS 12970, a specific thromboxane synthetase inhibitor (10 mg/kg, PO, q 8 h for 10 treatments). Platelet aggregation was assessed in whole blood by use of an electrical impedance method. Baseline values obtained prior to treatment served as controls. Addition of arachidonic acid to blood from nontreated dogs resulted in significantly (P less than 0.001) increased impedance, but had no effect in blood from dogs treated with either aspirin or CGS 12970. Treatment with CGS 12970 or aspirin significantly (P less than 0.001) decreased platelet ATP secretion in response to arachidonic acid, compared with baseline values; however ATP secretion in aspirin-treated dogs was significantly (P less than 0.01) less than ATP secretion in CGS 12970-treated dogs. Differences in platelet aggregation were not observed between control dogs and aspirin- or CGS 12970-treated dogs in response to collagen as an aggregant, however, collagen-induced platelet ATP secretion was significantly (P less than 0.001) decreased in dogs treated with aspirin, compared with control values and values from dogs treated with CGS 12970. In dogs treated orally with 0.1, 0.2, 1.0, or 10 mg of CGS 12970/kg, dose-dependent inhibition of arachidonic acid-induced platelet aggregation was observed, with impedance changes not observed at the 10-mg/kg dosage and normal platelet aggregation associated with the 0.1-mg/kg dosage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency of persistent bovine viral diarrhea virus infection in selected cattle herds

Sera and blood buffy coat samples were obtained from 3,157 cattle in 66 selected herds. Antibodies to bovine viral diarrhea (BVD) virus were detected in 89% of the serum samples by immunoprecipitation or virus-neutralization tests. Cytopathic or noncytopathic BVD viruses were isolated from blood buffy coat samples from 60 cattle in 6 herds. A second blood buffy coat sample was obtained from 54 of the 60 cattle 2 months after the initial sampling, and BVD virus was isolated again from each cow. The 54 cattle were considered persistently infected with BVD virus. The frequency of persistent infection was 1.7%.     

Evaluation of equine hemograms using the ADVIA 120 as compared with an impedance counter and manual differential count

BACKGROUND: The ADVIA 120 is an automated laser cell counter widely used in veterinary medicine. Although specific software for equine samples is available and validated, only a few reports have been published comparing the ADVIA 120 with other methods for equine hemogram evaluation. OBJECTIVES: The purpose of this study was to compare the hematologic values and reference intervals obtained on the ADVIA 120 with those obtained on an impedance cell counter and manual differential counts in healthy horses. METHODS: EDTA-anticoagulated blood samples were obtained from 114 clinically healthy horses of various breeds, both sexes, and 2-6 years of age. Samples were stored for up to 12 hours at 4 degrees C and then analyzed on the ADVIA 120 and the Hemat 8. A 100-cell to 200-cell differential leukocyte count was performed by 3 independent observers on May-Grünwald-Giemsa-stained smears. Intra-assay precision of the ADVIA 120 was determined by analyzing 5 replicates each of 10 of the blood samples. RESULTS: Results from the ADVIA were significantly higher than those from the impedance counter for RBC count, total WBC count, hemoglobin concentration, red cell distribution width, MCH, and MCHC, and significantly lower for HCT and platelet count. Significantly higher neutrophil and basophil counts and significantly lower lymphocyte counts were obtained with the ADVIA 120 compared with manual counts. Based on Passing-Bablok regression analysis, RBC and platelet counts were in good agreement between the 2 analyzers; a constant and proportional bias was present for other values. Coefficients of variation for erythrocyte parameters on the ADVIA were <1%, but were higher for platelet (6%), total WBC (2%), differential WBC (4%-30%), and reticulocyte (75%) counts. CONCLUSIONS: Results obtained with equine samples on the ADVIA 120 were comparable with those obtained on an impedance counter; reference intervals differed statistically but overlapped. The ADVIA had poor precision for reticulocyte and differential leukocyte counts such that the latter should always be verified on smears.