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.     

Comparative clinical study of canine and feline total blood cell count results with seven in‐clinic and two commercial laboratory hematology analyzers

Background: A CBC is an integral part of the assessment of health and disease in companion animals. While in the past newer technologies for CBC analysis were limited to large clinical pathology laboratories, several smaller and affordable automated hematology analyzers have been developed for in‐clinic use. Objectives: The purpose of this study was to compare CBC results generated by 7 in‐clinic laser‐ and impedance‐based hematology instruments and 2 commercial laboratory analyzers. Methods: Over a 3‐month period, fresh EDTA‐anticoagulated blood samples from healthy and diseased dogs (n=260) and cats (n=110) were analyzed on the LaserCyte, ForCyte, MS45, Heska CBC, Scil Vet ABC, VetScan HMT, QBC Vet Autoread, CELL‐DYN 3500, and ADVIA 120 analyzers. Results were compared by regression correlation (linear, Deming, Passing‐Bablok) and Bland–Altman bias plots using the ADVIA as the criterion standard for all analytes except HCT, which was compared with manual PCV. Precision, linearity, and carryover also were evaluated. Results: For most analytes, the in‐clinic analyzers and the CELL‐DYN performed similarly and correlated well with the ADVIA. The biases ranged from ?0.6 to 2.4 × 10⁹/L for WBC count, 0 to 0.9 × 10¹²/L for RBC count, ?1.5 to 0.7 g/dL for hemoglobin concentration, ?4.3 to 8.3 fL for MCV, and ?69.3 to 77.2 × 10⁹/L for platelet count. Compared with PCV, the HCT on most analyzers had a bias from 0.1% to 7.2%. Canine reticulocyte counts on the LaserCyte and ForCyte correlated but had a negative bias compared with those on the ADVIA. Precision, linearity, and carryover results were excellent for most analyzers. Conclusions: Total WBC and RBC counts were acceptable on all in‐clinic hematology instruments studied, with limitations for some RBC parameters and platelet counts. Together with evaluation of a blood film, these in‐clinic instruments can provide useful information on canine and feline patients in veterinary practices.     

Investigation into the causes of aspirin resistance in healthy dogs

Antiplatelet effects of acetylsalicylic acid (ASA, aspirin) may be poor in some individuals. Additionally, no method exists for predicting poor ASA response (resistance) in individual dogs. This study's main objective was to determine whether poor ASA response results from pharmacodynamic or pharmacokinetic causes. ASA concentrations causing 50% inhibition of platelet aggregation (in vitro IC50) were determined using whole blood collected from 21 drug‐free healthy dogs to evaluate intrinsic sensitivity of platelets to ASA. Dogs were then administered ASA at 4 mg/kg once orally. Percent decrease in platelet aggregation from baseline, and plasma ASA and salicylic acid (SA) concentrations (expressed as AUC values) were measured for up to 3 hr. By 3 hr, 13/21 (62%) dogs showed >50% aggregation inhibition, while 8/21 (38%) dogs showed <50% inhibition. Aggregation inhibition values were negatively correlated with in vitro IC50 values (Rs = ?0.49; p = 0.028) and positively correlated with ASA concentrations (Rs = 0.48; p = 0.03). Furthermore, ASA concentrations were strongly negatively correlated (Rs = ?0.88; p < 0.001) with SA/ASA concentration ratios, an index of ASA metabolism to SA by esterase enzymes. Multiple linear regression analysis indicated that 59% (p < 0.001) of interindividual variability in aggregation inhibition was explained by in vitro IC50 values (29% of variability) and ASA concentrations (29% of variability). Consequently, poor in vivo ASA response in these dogs resulted from both pharmacodynamic (decreased platelet sensitivity) and pharmacokinetic (lower ASA concentrations) causes. Lower ASA concentrations may be explained by reduced bioavailability associated with higher esterase activities.     

Suspected case of hypersplenism as a cause of anaemia,thrombocytopenia and leucopenia in a Miniature Horse gelding

A 23-year-old Miniature Horse gelding was presented to the Lloyd Veterinary Medical Center with a 3-week history of decreased appetite, lethargy and mild intermittent colic. A complete blood count revealed leucopenia, characterised by neutropenia and lymphopenia, as well as anaemia, thrombocytopenia and hyperproteinaemia whereas hypertriglyceridaemia was noted on serum biochemistry profile. Bone marrow evaluation was nondiagnostic and the horse was negative for antiplatelet antibody testing, Coombs test, equine infectious anaemia virus and Anaplasma phagocytophilum. The horse was hospitalised for 36 days and received supportive care, antibiotics, corticosteroids, dextrose-containing fluids and a whole blood transfusion. Following initial improvement and stabilisation, the horse became severely anaemic and acutely recumbent on Day 36 and was subjected to euthanasia. Post-mortem examination provided a diagnosis of hypersplenism with a markedly enlarged spleen along with histiocytic phagocytosis of erythrocytes and platelets. Examination of bone marrow showed appropriate erythroid hyperplasia and no evidence of myelopthisis or neoplasia. This report describes the first presumptive case of primary hypersplenism in an equid as a cause of pancytopenia.     

Mean platelet volume artifacts: the effect of anticoagulants and temperature on canine platelets

Improper handling of specimens results in artifactually high Mean Platelet Volume (MPV) measurements limiting their usefulness as a clinical tool. MPV measurement and Scanning Electron Microscopy (SEM) were performed on split specimens collected from normal dogs using two anticoagulants and two temperatures over a period of 4 hours. Platelets exposed to EDTA and maintained at 4 degrees C (39.2 degrees F) exhibited the highest artifactual increase in MPV, while those exposed to citrate and maintained at 37 degrees C (98.6 degrees F) exhibited minimal change. The increase in MPV was accompanied by platelet shape change from a smooth disc to an irregular sphere with filopodia. It is recommended that citrated specimens maintained at 37 degrees C be used in all MPV measurements.     

Uniform evaluation and semiquantitative reporting of hematologic data in veterinary laboratories

A protocol was presented for uniform evaluation and reporting of hematologic data in veterinary clinical laboratories. The protocol was used in the Clinical Pathology Laboratory at Michigan State University for 2 years and was found to improve the recognition and quantification of morphologic changes in blood smears.     

Evaluation of intra-articular injection of autologous platelet lysate (PL) in horses with osteoarthritis of the distal interphalangeal joint

Background: Regenerative medicine has become one of the most promising therapies of equine osteoarthritis. Platelet lysate (PL) is rich in bioactive proteins and growth factors that play a crucial role in tissue healing.

Objective: To evaluate the efficacy of intra-articularly injected autologous PL in equine athletes with naturally occurring osteoarthritis.

Animals and methods: Fifteen warmblood geldings aged 8–19 years with osteoarthritis of the distal interphalangeal joint were included in this study. They were randomly divided into two groups; 10 horses received intra-articular injections of PL and 5 of normal saline (controls). Before treatment, platelet-derived growth factor (PDGF) levels in basal plasma and prepared PL were estimated. Each joint was injected twice within a three-week period. Lameness was evaluated using the American Association of Equine Practitioners grading system, before treatment and 10 days after each intra-articular injection. Horses were examined fortnightly for one year. Radiographic examination was performed six months post-treatment. The generalized estimating equation test was used for statistical analysis.

Results: Acceptable levels of PDGF were detected in PLs (mean ± SD: 258.0 ± 52.3 pg/ml). The majority of horses (9/10) responded positively to PL treatment presenting lower lameness grades (p < 0.0005) compared to controls 10 days after the second injection, and returned to normal athletic activity. Radiographs revealed no changes in osteoarthritis lesions six months after treatment. One year post-injections, however, all horses relapsed to their initial degree of lameness.

Conclusion: Intra-articularly injected autologous PL is an efficient method for temporarily managing osteoarthritis of the distal interphalangeal joint in athletic horses.     

Evaluation of the in Vitro Anti-Atherogenic Properties of Lipid Fractions of Olive Pomace,Olive Pomace Enriched Fish Feed and Gilthead Sea Bream (Sparus aurata) Fed with Olive Pomace Enriched Fish Feed

Given the pivotal role of Platelet-Activating-Factor (PAF) in atherosclerosis and the cardio-protective role of PAF-inhibitors derived from olive pomace, the inclusion of olive pomace in fish feed has been studied for gilthead sea bream (Sparus aurata). The aim of the current research was to elucidate the anti-atherogenic properties of specific HPLC lipid fractions obtained from olive pomace, olive pomace enriched fish feed and fish fed with the olive pomace enriched fish feed, by evaluating their in vitro biological activity against washed rabbit platelets. This in vitro study underlines that olive pomace inclusion in fish feed improves the nutritional value of both fish feed and fish possibly by enriching the marine lipid profile of gilthead sea bream (Sparus aurata) with specific bioactive lipid compounds of plant origin.     

应用血小板计数对奶牛进行超早期妊娠诊断的研究

应用血小板计数对具有正常繁殖机能的249头黑白花奶牛进行超早期妊娠诊断的研究,结果较为满意。首先对51头黑白花奶牛进行最佳血检时间的试验,结果表明,30头妊娠母牛于配种后第7天血小板明显减少(p<0.01),而21头未妊母牛则无明显变化(p>0.05);根据妊娠母牛配种前与配种后第7天血小板数之差等于或大于70×10~3/mm~3为妊娠之标准,对198头母牛进行超早期妊娠诊断试验,经“直检”妊娠及空怀的符合率分别为80.67％(96/119)和89.87％(71/97);总符合率为84.34％(167/198)。