Platelet Counts In Dogs Research Articles

Effects of canine influenza infection and DA2PP vaccination on the development of platelet-associated immunoglobulins and platelet counts in dogs.

Immune thrombocytopenia (ITP) is commonly associated with platelet-associated immunoglobulins (PAIg). Demonstration of PAIg can help determine etiologies for thrombocytopenia. In humans, ITP and thrombocytopenia have been associated with various vaccinations and influenza infections, respectively. We aimed to evaluate platelet counts and PAIg in research dogs with H3N2 and in research and client-owned dogs routinely vaccinated for distemper, adenovirus-2, parainfluenza, and parvovirus (DA2PP). The hypotheses were that H3N2 infection but not DA2PP vaccination would decrease platelet counts, and neither would result in the detection of PAIg. Three pilot studies. Platelet counts and PAIg, measured by direct flow cytometry as %IgG, were evaluated in eight research Beagles following experimental infection with H3N2 (experiment 1), nine research Beagles vaccinated for DA2PP (experiment 2), and thirty client-owned dogs vaccinated for DA2PP (experiment 3). All animals were considered healthy at the start of the experiments. Transient, self-resolving decreases in platelet counts and increases in %IgG occurred following H3N2 infection, and one dog became thrombocytopenic and positive for PAIg. Following DA2PP vaccination, %IgG increased in research and client-owned dogs, but only one dog was considered positive for PAIg with a concurrent increase in platelet count. Mean PAIg increased from baseline in client-owned dogs following vaccination. Transient PAIg and thrombocytopenia can occur following H3N2 infection, while routine vaccination for DA2PP in this group of dogs was not associated with the development of thrombocytopenia or clinically relevant formation of PAIg.

Evaluation of the effect of vincristine on platelet count in dogs with lymphoma.

To determine the effect of vincristine administration on the platelet count, platelet morphology and incidence of thrombocytopenia in dogs diagnosed with lymphoma. Medical records of 59 dogs with lymphoma receiving vincristine sulphate were reviewed retrospectively. Following vincristine administration the platelet count was higher and the number of thrombocytopenic patients was lower. No difference was found in the number of dogs with enlarged and elliptical platelets following vincristine treatment. Vincristine administration increases platelet counts in dogs with lymphoma. It is not contra-indicated to administer vincristine to dogs with lymphoma that are thrombocytopenic.

Correlation of rotational thromboelastometry (ROTEM) parameters with platelet count and their ability to predict thrombocytopenia in dogs

The study objectivs were to evaluate the correlation between platelet count (PLT) and rotational thromboelastometry (ROTEM) parameters and to determine ROTEM cut-off values for identification of thrombocytopenia in dogs. Medical records of 113 dogs with concurrent EXTEM (ROTEM activated by proprietary tissue factor), FIBTEM (EXTEM with added cytochalasin D) analysis and PLT were retrospectively reviewed. Signalment, treatment prior to analysis, hematocrit (HCT), EXTEM/FIBTEM maximum clot firmness (MCFEXTEM, MCFFIBTEM), EXTEM/FIBTEM maximum clot elasticity (MCEEXTEM, MCEFIBTEM) and EXTEM maximum lysis (MLEXTEM) were extracted from patient records and ROTEM database. Delta (Δ) MCF was calculated as MCFEXTEM−MCFFIBTEM and ΔMCE as MCEEXTEM−MCEFIBTEM. The PLT was correlated to MCFEXTEM, MCEEXTEM, ΔMCF and ΔMCE using Spearman-Rho analysis. Correlations were further analyzed in thrombocytopenic dogs. The ability to predict thrombocytopenia was evaluated with receiver operating characteristics (ROC). Thirty-seven samples (32.7%) showed thrombocytopenia (<130 × 109/L) and 19 samples (17%) severe thrombocytopenia (<60* x 109/L). The PLT significantly correlated with MCFEXTEM (r = 0.545, P < .001), MCEEXTEM (r = 0.547, P < .001), ΔMCF (r = 0.441, P < .001) and ΔMCE (r = 0.559, P < .001). MCFEXTEM < 49 mm, MCEEXTEM < 93, ΔMCF <42 mm and ΔMCE <90 predicted thrombocytopenia <60 × 109/L with a sensitivity of 90% and a specificity of 78% with a negative predictive value >97% for all 4 parameters. In conclusion, PLT in dogs correlated moderately but significantly with all evaluated ROTEM parameters. All parameters were able to rule out thrombocytopenia <60 × 109/L with a high negative predictive value, while the sensitivity to predict thrombocytopenia was only moderate and the positive predictive value was low.

Analytical variability of estimated platelet counts on canine blood smears.

The analytical variability of estimated platelet counts in dogs has not been reported. The purpose of this study was to assess the magnitude of analytical imprecision of platelet estimates and the possible impact of this imprecision on clinical decisions. Three independent observers counted the number of platelets in 3 different areas (LE=lateral edge; CM=central monolayer; FE=feathered edge) of 30 canine blood smears with different instrumental platelet counts. The coefficient of variation (CV) for each observer was calculated in different areas of each smear (intra-observer variability), among different regions of each smear (inter-area variability), and among different observers in each area (inter-observer variability). The influence of these variabilities on the classification of platelet estimates as adequate, increased, or decreased was also assessed. The CVs recorded in the different areas by each observer ranged from 8% to 88% and were negatively correlated (P<.001, r=-.65) with the mean number of platelets per field. The mean platelet number was significantly lower in the FE and significantly higher in the CM compared with the LE, but the magnitude of this difference varied with the operators. The concordance among operators regarding platelet estimates was fair (k=0.36) to substantial (k=0.71) depending on the area. The overall inter-area concordance was moderate (k=0.59). Platelet estimates suffer from high variability that could lead to patient misclassification. Therefore, guidelines to standardize the platelet estimate are needed.

Magnitude of reactive thrombocytosis and associated clinical conditions in dogs

Previous studies on the underlying causes of thrombocytosis have raised scientific interest in its clinical relevance in dogs. The purpose of this study was: (1) to explore the clinical conditions...

Effect of prewarming EDTA blood samples to 37°C on platelet count measured by Sysmex XT-2000iV in dogs, cats, and horses.

Pseudothrombocytopenia secondary to platelet clumping is a common cause of preanalytic error for platelet counts in dogs, cats, and horses. In human beings, it is suggested that prewarming blood samples to 37°C prior to hematology analysis will reduce platelet clumping. The purpose of the study was to evaluate the effect of prewarming EDTA blood samples to 37°C on measured platelet counts and other hematologic variables. The EDTA blood samples from dogs, cats and horses submitted to the clinical pathology laboratory at the University of Cambridge were included. Complete blood cell counts performed using a Sysmex XT-2000iV hematology analyzer were done on samples at room temperature (approximately 22°C) and following warming of the samples to 37°C in a water bath. The Wilcoxon signed rank test was used to compare hematologic variables, including platelet count, before and after sample warming to 37°C. Data are presented as median (25(th) , 75(th) percentile) increase. Blood samples from 39 dogs, 19 cats, and 10 horses were included. Sample warming to 37°C resulted in a statistically significant increase in platelet counts in dogs (11 [-2, 30] ×10(9) /L), cats (36 [14, 84] ×10(9) /L), and horses (42 [31, 79] ×10(9) /L). Sample warming did not significantly affect other hematologic variables. Prewarming EDTA blood samples to 37°C prior to hematologic analysis increased platelet counts overall in canine, feline, and equine blood, but did not abrogate platelet clumping and pseudothrombocytopenia fully in some cases. Furthermore, true pseudothrombocytopenia was not confirmed in these animals.

Avaliação da coagulação plasmática e plaquetometria em cães não infectados e infectados experimentalmente com Ehrlichia spp.

Avaliou-se a ocorrência de distúrbios na coagulação plasmática e na plaquetometria de cães infectados por Ehrlichia spp., durante 15 semanas após o contágio. Doze cães, entre machos e fêmeas, nascidos em estação experimental e com idades entre um e dois anos, foram usados no experimento. Nove cães foram infectados experimentalmente com sangue de cão naturalmente portador de Ehrlichia spp. e três foram mantidos como controle. As alterações na coagulação plasmática não diferiram entre cães infectados e não infectados. A plaquetometria oscilou durante as 15 semanas entre 61x10³/μL e 830x10³/μL, e o menor valor médio foi de 113x10³/μL na sexta semana após a infecção. Concluiu-se que a coagulação plasmática não apresentou alterações significativas nas 15 semanas após infecção e que a contagem plaquetária oscilou entre valores normais, elevados e reduzidos durante esse período.

Validation of the Sysmex XT‐2000iV hematology system for dogs, cats, and horses. I. Erythrocytes, platelets, and total leukocyte counts

The Sysmex XT-2000iV is a laser-based, flow cytometric hematology system that has been introduced for use in large and referral veterinary laboratories. The purpose of this study was to validate the Sysmex XT-2000iV for counting erythrocytes, reticulocytes, platelets, and total leukocytes in blood from ill dogs, cats, and horses. Blood samples from diseased animals (133 dogs, 65 cats, and 73 horses) were analyzed with the Sysmex XT-2000iV and the CELL-DYN 3500. Manual reticulocyte counts were done on an additional 98 canine and 14 feline samples and manual platelet counts were done on an additional 73 feline and 55 canine samples, and compared with automated Sysmex results. Hemoglobin concentration, RBC counts, and total WBC counts on the Sysmex were highly correlated with those from the CELL-DYN (r>/=0.98). Systematic differences occurred for MCV and HCT. MCHC was poorly correlated in all species (r=0.33-0.67). The Sysmex impedance platelet count in dogs was highly correlated with both the impedance count from the CELL-DYN (r=0.99) and the optical platelet count from the Sysmex (r=0.98). The Sysmex optical platelet count included large platelets, such that in samples from cats, the results agreed better with manual platelet counts than with impedance platelet counts on the Sysmex. Canine reticulocyte counts on the Sysmex correlated well (r=0.90) with manual reticulocyte counts. Feline reticulocyte counts on the Sysmex correlated well with aggregate (r=0.86) but not punctate (r=0.50) reticulocyte counts. The Sysmex XT-2000iV performed as well as the CELL-DYN on blood samples from dogs, cats, and horses with a variety of hematologic abnormalities. In addition, the Sysmex detected large platelets and provided accurate reticulocyte counts.

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

Platelet aggregates are a common artifact in canine blood. Aggregates may affect the accuracy of platelet counts, with important consequences for patient care. 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. 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. 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. 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.

Experimental canine leptospirosis caused by Leptospira interrogans serovars pomona and bratislava

To evaluate gross, histopathologic, and serum biochemical findings caused by Leptospira interrogans serovars pomona and bratislava inoculated in dogs. Twenty-seven 8-week-old female Beagles. Dogs were randomly assigned to challenge or control groups. Challenge groups were conjunctivally inoculated on 3 successive days with 5 x 10(7) L interrogans serovar pomona (n = 12) or serovar bratislava (11). Clinical signs were recorded throughout the experiment, and clinical pathology assays, bacteriologic culture, and necropsies (6 or 7 dogs necropsied at each time point) were done on postinoculation day (PID) 7, 10, 14, and 20. Infection could not be confirmed in any serovar bratislava-inoculated dog, and control dogs remained healthy throughout the experiment. Positive culture and fluorescent antibody test results were confirmed in 11 of 12 serovar pomona-inoculated dogs. Fever and lethargy starting at PID 7 were the most common clinical signs in serovar pomona-infected dogs. On day 10, gross lesions included multifocal renal and pulmonary hemorrhage and perirenal edema. Serovar pomona-inoculated dogs had histopathologic lesions including hepatitis, interstitial nephritis, and pneumonia at PID 7, 10, 14, and 20. Increases in BUN, anion gap, and bilirubin concentration occurred on PID 10, 14, and 20. Platelet counts in dogs with positive results of bacteriologic culture were decreased from baseline values on PID 10, 12, and 14. Conjunctival inoculation with L interrogans serovar pomona resulted in a high rate of infection with concomitant hemorrhagic and inflammatory lesions of the kidneys, liver, and lungs.

Correlation of spurious potassium elevation and platelet count in dogs.

Paired serum and plasma electrolyte determinations were measured on 26 dogs. The difference between plasma and serum electrolyte concentrations was compared to the platelet and leukocyte counts. An increase in serum potassium concentration over plasma potassium concentration was found which correlated linearly with the platelet count. No correlation with white cell count was found. A statistically significant increase in serum sodium concentration over plasma sodium concentration was also noted, however, this change did not correlate with the number of platelets or white cells. It is concluded that thrombocytosis, previously known to cause spurious elevation in serum potassium concentration in humans, can also do so in dogs and, presumably, other species.

Studies on the effect of a coumarin on blood platelets.

Abstract Studies with a synthetic coumarin, ethoxarine, have shown it to increase the blood platelet count in rats and rabbits after intravenous or oral administration. This agent protected rabbits against a platelet antibody-induced thrombocytopenia but not against the platelet lowering effects of x-ray. This finding suggests strongly that it exerts its influence on megakaryocyte reproduction. Ethoxarine had no effect on the platelet count in dogs during either acute or chronic treatment.

The Rate of Regeneration of Blood Platelets

By repeatedly withdrawing, defibrinating, and reinjecting blood, the platelet count in dogs can be reduced to an extremely low level. When the reduction in platelets and fibrinogen has been carried to an extreme degree the animals display a marked tendency to bleed. The regeneration of platelets after their removal by defibrination is remarkably rapid and amounts, on an average, to about one fifth of the entire number in the blood per day. From the experiments and from observations on the platelet count in human beings, it is believed that under the usual conditions of life platelets are utilized or destroyed and replaced in enormous numbers daily, and that the life cycle of the platelet is extremely short,—possibly a matter of a few days.

THE RATE OF REGENERATION OF BLOOD PLATELETS

By repeatedly withdrawing, defibrinating, and reinjecting blood, the platelet count in dogs can be reduced to an extremely low level. When the reduction in platelets and fibrinogen has been carried to an extreme degree the animals display a marked tendency to bleed. The regeneration of platelets after their removal by defibrination is remarkably rapid and amounts, on an average, to about one fifth of the entire number in the blood per day. From the experiments and from observations on the platelet count in human beings, it is believed that under the usual conditions of life platelets are utilized or destroyed and replaced in enormous numbers daily, and that the life cycle of the platelet is extremely short,-possibly a matter of a few days.