Effect of needle gauge on pain and specimen quality of ultrasound-guided fine needle sampling without aspiration of the canine spleen.

Modifications of splenic parenchyma are common ultrasonographic findings in dogs. Splenic fine needle aspiration (FNA) is a rapid, safe procedure, routinely performed in veterinary institutions. However, 22-gauge (G) needle usually reported is selected according to general practice and the most appropriate needle size to be used remains unclear. The aim of this prospective, single-center, methods comparison study was to assess the effect of needle size on cytologic specimens' evaluation and animal welfare during the procedure. Dogs underwent ultrasound-guided splenic FNA using 23, 25, and 27G needles. Needles were compared based on initial and then detailed cytologic evaluation. The initial evaluation assessed overall cellularity, cell preservation, hemodilution, and detailed cytologic evaluation referred to exhaustive splenic components. Welfare evaluation was performed based on a scoring system. A total of 54 dogs were included in this study with 54 of 54 welfare evaluations and 35 of 54 cytologic evaluations by one or two European College of Veterinary Clinical Pathology-certified cytologists. The final cytologic diagnosis was unchanged regardless of the needle size. For the initial evaluation, 23G needles provided significantly higher cellularity than the 27G needles. For detailed cytologic evaluation, only the richness in mesothelial cells and stroma was affected by needle size. Pain induced by the procedures was considered low using 23, 25, and 27G needles with the 27G needle producing the least adverse reactions. Findings from the current study supported using needle gauges smaller than the previously published standard 22G needle for spleen ultrasound-guided fine needle nonaspiration in dogs. Due to higher cellularity and lower pain scores, authors recommend the use of 23G needles with a nonaspiration technique.

Age and spatio-temporal variations in food resources modulate stress-immunity relationships in three populations of wild roe deer.

Living in variable and unpredictable environments, organisms face recurrent stressful situations. The endocrine stress response, which includes the secretion of glucocorticoids, helps organisms to cope with these perturbations. Although short-term elevations of glucocorticoid levels are often associated with immediate beneficial consequences for individuals, long-term glucocorticoid elevation can compromise key physiological functions such as immunity. While laboratory works highlighted the immunosuppressive effect of long-term elevated glucocorticoids, it remains largely unknown, especially in wild animals, whether this relationship is modulated by individual and environmental characteristics. In this study, we explored the co-variation between integrated cortisol levels, assessed non-invasively using faecal cortisol metabolites (FCMs), and 12 constitutive indices of innate, inflammatory, and adaptive immune functions, in wild roe deer living in three populations with previously known contrasting environmental conditions. Using longitudinal data on 564 individuals, we further investigated whether age and spatio-temporal variations in the quantity and quality of food resources modulate the relationship between FCMs and immunity. Negative covariation with glucocorticoids was evident only for innate and inflammatory markers of immunity, while adaptive immunity appeared to be positively or not linked to glucocorticoids. In addition, the negative covariations were generally stronger in individuals facing harsh environmental constraints and in old individuals. Therefore, our results highlight the importance of measuring multiple immune markers of immunity in individuals from contrasted environments to unravel the complex relationships between glucocorticoids and immunity in wild animals. Our results also help explain conflicting results found in the literature and could improve our understanding of the link between elevated glucocorticoid levels and disease spread, and its consequences on population dynamics.

Subconjunctival nodule due to Setaria equina erratic migration in a horse: First case report.

An 18-month-old Arabian-English filly resident in southwest France was referred for evaluation of a conjunctival mass in the right eye (OD). A pink, solid, and mobile nodular formation, measuring approximately 1.2 × 0.8 cm was found under the superior nasal bulbar conjunctiva during an ophthalmic examination that was otherwise normal. The mass was surgically removed using a standing procedure. Cytological examination of fine-needle aspirates from the mass revealed a mixed eosinophilic-lymphocytic inflammation. Histological examination confirmed the dense and diffuse eosinophilic-lymphocytic infiltrate of the mass, and it revealed several cross sections of a parasitic nematode. The morphometric diagnosis identified an immature form of a filarial worm, and molecular analysis of the mitochondrial cytochrome c oxydase subunit 1 (cox1) and 12S rRNA gene sequences led to further identification of the specimen as Setaria equina. Microfilaremia was not observed on fresh blood smears. There have been no signs of local recurrence after 18 months, nor any evidence of intraocular involvement. To the authors' knowledge, this is the first documented case of subconjunctival setariasis due to S equina in a horse.

Hematology reference intervals for adult cows in France using the Sysmex XT-2000iV analyzer.

In order to develop bovine hematology reference intervals (RIs) in accordance with new international recommendations, we analyzed 156 blood specimens of healthy adult dairy and beef cows from 32 farms with a Sysmex XT-2000iV analyzer, and by manual scoring of platelet clumps and white blood cell (WBC) differential. We established RIs by the nonparametric method, and examined effects of age, production type (beef vs. dairy), and stage of lactation. RIs could not be determined for platelet count and indices because clumps were observed in 80% of specimens. Optical and impedance red blood cell (RBC) counts were similar, although statistically different. RIs for analyzer and manual WBC differentials were not different except for lymphocyte concentration, the subpopulations of which were counted manually. Hematocrit was higher in beef than dairy cattle, and hemoglobin was lower in early lactation. Increases in RBC count, mean corpuscular volume, mean corpuscular hemoglobin, and RBC distribution width were noted with increasing age, along with decreases in WBC count, neutrophils, and lymphocytes. Most RIs in our study, with the exception of neutrophils, were similar to those previously reported using a flow cytometry analyzer.

Evaluation of CTAD (citrate-theophylline-adenosine-dipyridamole) as a universal anticoagulant in dogs.

CTAD (citrate-theophylline-adenosine-dipyridamole) has been shown to be an almost universal anticoagulant in human and feline medicine, allowing most hematology, coagulation, and biochemical analyses. Forty canine blood specimens were collected in CTAD, EDTA, heparin, and citrate for hematology, biochemistry, and coagulation analyses. CTAD partially limited platelet aggregation observed in EDTA blood smears. CTAD specimens gave similar and well-correlated results for most variables of a complete blood cell count, except for mean corpuscular volume, which was moderately higher, and mean corpuscular hemoglobin concentration, which was moderately lower in CTAD than in EDTA; reticulocyte and platelet indexes were poorly correlated. CTAD plasma gave similar results to citrate for fibrinogen, antithrombin, and D-dimers, and relatively similar results for prothrombin time, but activated partial thromboplastin time was poorly correlated. Triglycerides, cholesterol, glucose, total proteins, phosphate, iron, alanine aminotransferase, γ-glutamyl transferase, and lipase were similar and well correlated in CTAD and heparin plasmas. Urea, creatinine, albumin, alkaline phosphatase, amylase, and aspartate aminotransferase showed moderate-to-marked bias, but these variables could be measured in CTAD plasma if new reference intervals were determined. Creatine kinase activity, potassium, chloride, and total carbon dioxide measurements are not recommended in CTAD plasma. CTAD is a prospective candidate as an almost universal anticoagulant for routine hematology, some plasma coagulation, and many biochemistry variables in dogs. Definitive recommendations will require study of abnormal canine blood specimens.

Comparison of different anticoagulant associations on haemostasis and biochemical analyses in feline blood specimens.

Objectives Universal anticoagulant could be an alternative to the multiple blood sampling required for clinical pathology investigations in cats. An association of citrate, theophylline, adenosine and dipyridamole (CTAD) has been reported to be a good substitute for EDTA for haematology analysis in cats, limiting platelet clumping, and has also been shown to be valid for haematology, secondary haemostasis and some biochemical variables in humans. The aim of the study was therefore to investigate the effects of CTAD on in vitro platelet aggregation and compare results of secondary haemostasis and biochemistry tests, excluding a priori those variables not reliably measured in CTAD, such as sodium, chloride and divalent cations, in feline blood specimens collected in CTAD and paired citrate and heparin tubes. Methods Thirty blood specimens sampled in citrate and CTAD were analysed for in vitro platelet aggregation, and 60 blood specimens sampled in citrate or heparin and CTAD were analysed for plasma coagulation and a biochemistry panel. Results In vitro platelet aggregation was inhibited in CTAD compared with citrate specimens. Prothrombin time, activated partial thromboplastin time, antithrombin and fibrinogen results were similar, despite some significant differences. Measurements of triglycerides, cholesterol, glucose, urea, creatinine, phosphate, total proteins and alanine aminotransferase activity were similar and well correlated in CTAD and heparin plasmas, despite some significant differences and moderate biases. Albumin showed a marked positive proportional bias, and creatine kinase and alkaline phosphatase activities a moderate and marked negative mixed bias, respectively, but could be measured in CTAD if new reference intervals were calculated. Aspartate aminotransferase activity showed a marked negative proportional bias, along with a poor correlation and some clinical misclassifications just like the potassium concentration, and thus cannot be recommended to be measured in CTAD specimens. Conclusions and relevance In cats, CTAD cannot be used for primary haemostasis investigation but could be a suitable (almost) universal anticoagulant for routine haematology, as well as for plasma coagulation and many biochemistry variables.

Hematologic and Biochemical Biologic Variation in Laboratory Cats.

The biologic variation associated with a clinical pathology result is important to consider before reference intervals (RI) are used. Most available RI are population-based RI, in which the analytical variability, interindividual variability, and intraindividual variability are confounded. In addition, when the intraindividual variability is considerably less than the interindividual variability, a population-based RI is insufficiently sensitive to detect changes in a subject over time. Here we determined the biologic variation and reference change value (RCV) of hematologic and biochemical variables in laboratory cats. Blood specimens from 14 (7 females and 7 males) overnight-fasted laboratory cats sampled 7 times (days 1, 2, 7, 14, 31, 42, and 100) were analyzed regarding hematology and biochemistry variables. For each variable, analytical, intraindividual, and interindividual coefficients of variation were estimated prior to calculation of the index of individuality and the RCV. RBC variables (count, Hgb, Hct, MCV, MCH, MCHC, and RBC distribution width) and 5 biochemical analytes (cholesterol, creatinine, triglycerides, ALP, and calcium) exhibited marked individuality, therefore indicating that subject-based reference intervals or RCV would be preferable when monitoring these variables in laboratory cats. Population-based RI were shown to be adequate for glucose and sodium, and both types of population and individual RI were similarly efficient for albumin, total protein, urea, ALT, AST, creatine kinase, chloride, carbon dioxide, iron, magnesium, inorganic phosphate, and potassium and reticulocyte, WBC, neutrophil, lymphocyte, monocyte, eosinophil, and platelet counts. The RCV determined in the present study provide a valuable tool for monitoring hematologic and biochemical variables in healthy laboratory cats.

Adsorption of tranexamic acid on hydroxyapatite: Toward the development of biomaterials with local hemostatic activity.

This work proposes to combine tranexamic acid (TAX), a clinically used antifibrinolytic agent, and hydroxyapatite (HA), widely used in bone replacement, to produce a novel bioactive apatitic biomaterial with intrinsic hemostatic properties. The aim of this study was to investigate adsorptive behavior of the TAX molecule onto HA and to point out its release in near physiological conditions. No other phase was observed by X-ray diffraction or transmission electron microscopy, and no apparent change in crystal size was detected. The presence of TAX on the powders was lightly detected on Raman spectra after adsorption. The adsorption data could be fitted with a Langmuir-Freundlich equation, suggesting a strong interaction between adsorbed molecules and the formation of multilayers. The concentration of calcium and phosphate ions in solution remained low and stable during the adsorption process, thus ion exchange during the adsorption process could be ruled out. The release of TAX was fast during the first hours and was governed by a complex process that likely involved both diffusion and dissolution of HA. Preliminary aPTT (activated partial thromboplastin time) hemostasis tests offered promising results for the development of osteoconductive apatitic biomaterials with intrinsic hemostatic properties, whether for dental or orthopedic applications.

Reference intervals, intraindividual and interindividual variability, and reference change values for hematologic variables in laboratory beagles.

In research and development studies for human and veterinary medicine, relevant comparators for interpreting clinical pathology results are matched with concurrent control animals. However, reference intervals (RI) provide a comparator database and important aids for interpreting clinical pathology data, especially in laboratory beagle dogs. Furthermore, RI incorporate biologic variation, which includes analytical, intraindividual, and interindividual variation. No studies to date have established RI and studied the effect of biologic variation on hematologic variables in a large group of laboratory dogs. The purpose of this retrospective study was to establish hematologic RI for laboratory beagles according to international recommendations and estimate the effect of biologic variation in routinely measured hematologic analytes by using the databank at a pharmaceutical center. Blood specimens from 340 healthy beagles (age, 9 to 36 mo) were evaluated by using a flow-cytometry-based hematology analyzer. RI and their 90% confidence intervals were established by using a nonparametric method. Effects of sex, age, and weight were investigated. Weight had no effect on any analyte. RBC, Hgb, Hct, MCV, MCH, RBC distribution width, and platelet count increased with age, whereas WBC count decreased. The only clinically relevant effect of sex was observed for platelets, which were lower in male beagles than in female and warranted 2 different RI. The calculated index of individuality showed that population-based RI were appropriate for almost all hematologic analytes, as might be expected for a homogeneous group of laboratory beagles.

The preanalytic phase in veterinary clinical pathology.

This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.

Changes in hematology measurements in healthy and diseased dog blood stored at room temperature for 24 and 48 hours using the XT-2000iV analyzer.

BACKGROUND: Changes in canine hematology measurements may occur when analyses are delayed due to shipment of specimens to a laboratory. OBJECTIVE: The purpose of this study was to report changes in hematologic variables in healthy and diseased canine blood measured with a Sysmex XT-2000iV during storage at room temperature for 24 and 48 hours. METHODS: EDTA-K3 blood samples from 42 healthy and diseased dogs were measured on a Sysmex XT-2000iV analyzer within one hour of sampling, and after storage for 24 and 48 hours at room temperature in the dark. RESULTS: Storage caused little or no change in RBC count, HGB concentration and MCH, while there was a moderate increase in HCT, MCV and reticulocytes count, and a moderate decrease in MCHC. Decreased platelet counts by impedance (PLT-I) and optical (PLT-O) measurements were associated with increased mean platelet volume (MPV), platelet-large cell ratio (P-LCR) and platelet distribution width (PDW), including a right shift in the platelet histogram and a dispersion of the platelet dot plot on the scattergram. The total and differential WBC count remained stable except for decreased monocyte counts. In the scatterplots, monocytes shifted into the lymphocyte population after 24 hours, and neutrophil population shifted to the right appearing in the eosinophil gate at 48 hours of storage. The disease status had only a small effect on storage-induced changes, and observed changes had no consequences for clinical decisions. CONCLUSIONS: Blood storage at room temperature was accompanied by moderate variations in some hematologic variables, awareness of which helps in avoiding misinterpretations.

Feline reference intervals for the Sysmex XT-2000iV and the ProCyte DX haematology analysers in EDTA and CTAD blood specimens.

Laser-based haematology analysers are routinely used in veterinary clinical pathology laboratories, and are available to practitioners. However, feline haematological reference intervals (RIs) determined according to international recommendations are, to our knowledge, not available. Furthermore, platelet count RI is difficult to establish in cats because of the frequent occurrence of platelet aggregation in blood specimens. The purpose of this study was to establish feline haematological RIs with the Sysmex XT-2000iV and ProCyte DX analysers, in ethylenediamine tetra-acetic acid (EDTA) and in citrate, theophylline, adenosine and dipyridamole (CTAD), which is a combination of anticoagulants limiting platelet aggregation. Blood specimens from 120 healthy cats were analysed in duplicate, and the degree of platelet aggregation was assessed on blood smears. After exclusion of inadequate specimens, 81 sets of results (from 44 males and 37 females, aged from 6 to 116 months) were available for the determination of RIs by the non-parametric method. The effects of the anticoagulant, analyser and aggregation score were assessed. When the aggregation effect was significant, the RIs were determined using the subgroup of blood specimens with no or little aggregation. The effects of sex, age and weight were also investigated, but were moderate. The different RIs obtained with the Sysmex XT-2000iV and ProCyte DX analysers, and the two anticoagulants, were very similar to previous RIs established in EDTA with the ADVIA 120, another laser-based analyser, except for the platelet count in CTAD specimens. Its lower reference limit was higher in CTAD vs EDTA specimens, which confirms the interest in this anticoagulant in cats.

Changes in haematology measurements with the Sysmex XT-2000iV during storage of feline blood sampled in EDTA or EDTA plus CTAD.

In veterinary medicine a complete blood cell count (CBC) cannot always be performed within 24 h as usually recommended, particularly for specimens shipped to a reference laboratory. This raises the question of the stability of the variables, especially in ethylenediamine tetra-acetic acid (EDTA) feline blood specimens, known to be prone to in vitro platelet aggregation. Citrate, theophylline, adenosine and dipyridamole (CTAD) has been reported to limit platelet aggregation in feline blood specimens. The aim of this study was to measure the stability of the haematological variables and the platelet aggregation score in EDTA and EDTA plus CTAD (EDCT) feline blood specimens during 48 h of storage at room temperature. Forty-six feline EDTA and EDCT blood specimens were analysed with a Sysmex XT-2000iV analyser, and the platelet count and score of platelet aggregation were estimated immediately and after 24 and 48 h of storage. A significant increase in mean corpuscular volume, haematocrit, reticulocyte and eosinophil counts, and a significant decrease in mean corpuscular haemoglobin concentration and monocyte count were observed. Haemoglobin, mean corpuscular haemoglobin, and red blood cell, white blood cell, neutrophil and lymphocyte counts remained stable. Changes in reticulocyte indexes with time (low fluorescence ratio, medium fluorescence ratio, high fluorescence ratio and immature reticulocyte fraction) were not significant. Changes were generally more pronounced in EDTA than in EDCT. Platelet aggregation decreased markedly in initially highly aggregated EDTA specimens, and increased slightly in initially non- or mildly-aggregated EDTA or EDCT specimens. Platelet counts increased and decreased, or remained stable, respectively. CTAD can reduce storage-induced changes of the haematological variables in feline samples, thus improving the reliability of a CBC and limiting clinical misinterpretations.

Effects of intravenous, low-dose ketamine-diazepam sedation on the results of hematologic, plasma biochemical, and coagulation analyses in cats.

OBJECTIVE: To evaluate the effects of an IV, low-dose ketamine-diazepam combination used for short-duration chemical restraint on the results of clinicopathologic testing in cats and to assess its practicality and tolerance. DESIGN: Prospective case series. ANIMALS: 42 client-owned cats of various breeds, ages, and health status. PROCEDURES: Blood samples were obtained just prior to and just after IV injection of ketamine chlorhydrate (10 mg) and diazepam (0.5 mg). A CBC, plasma biochemistry panel, and coagulation profile were performed on each sample (ie, before and after chemical restraint). Practicality of the procedure was assessed, and cats were monitored for immediate and delayed effects. RESULTS: Significant changes were observed for most of the analytes tested. However, the magnitude of the observed changes was notably low and likely not of clinical relevance. The chemical-restraint procedure appeared effective, safe, and well tolerated. CONCLUSIONS AND CLINICAL RELEVANCE: The IV, low-dose ketamine-diazepam combination used for short-duration chemical restraint in the present study may be suitable to assist physical restraint for blood sampling for assessment of hematologic, serum biochemical, and coagulation parameters in cats.

Comparison of platelet clumping and complete blood count results with Sysmex XT-2000iV in feline blood sampled on EDTA or EDTA plus CTAD (citrate, theophylline, adenosine and dipyridamole).

False thrombocytopenia may result from platelet aggregation, especially in feline ethylenediamine tetra-acetic acid (EDTA) blood specimens. Citrate, theophylline, adenosine and dipyridamole (CTAD) was added to 46 feline EDTA specimens to test its anti-aggregation action. Platelet aggregation was estimated from blood films and a complete blood count was performed with a Sysmex XT-2000iV analyser. Platelet aggregation score was >2 in 11/46 EDTA tubes and only in one EDTA+CTAD specimen. The platelet count was higher in all CTAD-supplemented tubes except one, medians measured by cytometry being 225.5 × 10(9)/l and 249.0 × 10(9)/l in EDTA and EDTA+CTAD, respectively (P = 0.007). Adding CTAD had statistically and analytically significant but moderate effects on other blood variables, the most intense variations being observed for reticulocytes (about 3% higher in EDTA specimens) and reticulocyte indexes. Addition of CTAD to EDTA when sampling feline blood is a useful option to reduce platelet clumping.

Canine reference intervals for the Sysmex XT-2000iV hematology analyzer.

BACKGROUND: The laser-based Sysmex XT-2000iV hematology analyzer is increasingly used in veterinary clinical pathology laboratories, and instrument-specific reference intervals for dogs are not available. OBJECTIVE: The purpose of this study was to establish canine hematologic reference intervals according to International Federation of Clinical Chemistry and Clinical and Laboratory Standards Institute guidelines using the Sysmex XT-2000iV hematology analyzer. METHODS: Blood samples from 132 healthy purebred dogs from France, selected to represent the most prevalent canine breeds in France, were analyzed. Blood smears were scored for platelet (PLT) aggregates. Reference intervals were established using the nonparametric method. PLT and RBC counts obtained by impedance and optical methods were compared. Effects of sex and age on reference intervals were determined. RESULTS: The correlation between impedance (I) and optical (O) measurements of RBC and PLT counts was excellent (Pearson r=.99 and .98, respectively); however, there were significant differences between the 2 methods (Student's paired t-test, P<.0001). Differences between sexes were not significant except for HCT, PLT-I, and PLT-O. WBC, lymphocyte, and neutrophil counts decreased significantly with age (ANOVA, P<.05). Median eosinophil counts were higher in Brittany Spaniels (1.87 × 10(9) /L), Rottweilers (1.41 × 10(9) /L), and German Shepherd dogs (1.38 × 10(9) /L) than in the overall population (0.9 × 10(9) /L). PLT aggregates were responsible for lower PLT counts by the impedance, but not the optical, method. CONCLUSION: Reference intervals for hematologic analytes and indices were determined under controlled preanalytical and analytical conditions for a well-characterized population of dogs according to international recommendations.

Reference Value Advisor: a new freeware set of macroinstructions to calculate reference intervals with Microsoft Excel.

International recommendations for determination of reference intervals have been recently updated, especially for small reference sample groups, and use of the robust method and Box-Cox transformation is now recommended. Unfortunately, these methods are not included in most software programs used for data analysis by clinical laboratories. We have created a set of macroinstructions, named Reference Value Advisor, for use in Microsoft Excel to calculate reference limits applying different methods. For any series of data, Reference Value Advisor calculates reference limits (with 90% confidence intervals [CI]) using a nonparametric method when n≥40 and by parametric and robust methods from native and Box-Cox transformed values; tests normality of distributions using the Anderson-Darling test and outliers using Tukey and Dixon-Reed tests; displays the distribution of values in dot plots and histograms and constructs Q-Q plots for visual inspection of normality; and provides minimal guidelines in the form of comments based on international recommendations. The critical steps in determination of reference intervals are correct selection of as many reference individuals as possible and analysis of specimens in controlled preanalytical and analytical conditions. Computing tools cannot compensate for flaws in selection and size of the reference sample group and handling and analysis of samples. However, if those steps are performed properly, Reference Value Advisor, available as freeware at http://www.biostat.envt.fr/spip/spip.php?article63, permits rapid assessment and comparison of results calculated using different methods, including currently unavailable methods. This allows for selection of the most appropriate method, especially as the program provides the CI of limits. It should be useful in veterinary clinical pathology when only small reference sample groups are available.

Validation of preexisting reference intervals: can the procedure be applied to canine hemostasis?

The de novo establishment of reference intervals (RIs) for all variables is beyond the capabilities of many small laboratories. Thus, recent international recommendations propose procedures to adopt RIs established by "donor" laboratories after validation in "receiving" laboratories. The objective of the current study was to use recently published RIs of canine hemostasis tests as possible donor values and evaluate the validation procedure with randomized sets of values obtained in another study of canine RI determination of prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, and antithrombin (AT). The preanalytical, analytical, and demographic conditions of the donor and receiving laboratories were first compared. To represent new reference individuals, 25 validation sample sets of 20 results of the receiving laboratory were randomly selected for each variable and compared with the RI of the donor laboratory. Validation was rejected in all cases for APTT and AT. Donor RI could be validated in 14 of 25 cases for fibrinogen and in 4 of 25 cases for PT. When preanalytical and analytical differences existed between donor and receiving laboratories, validation procedures consistently rejected preexisting RI. When the differences are smaller, the variability of the results obtained in the validation sample sets tested may be responsible for validations or rejections, which can lead to further misinterpretations of results from patients. Validation of a preexisting reference interval is certainly an interesting option for small laboratories, but progressive determination of the laboratory's own reference interval is probably a better long-term solution.

Canine reference intervals for coagulation markers using the STA Satellite(R) and the STA-R Evolution(R) analyzers.

The aim of the current study was to determine canine reference intervals for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, and antithrombin (AT) according to international recommendations. The STA Satellite(R) coefficients of variation of within-laboratory imprecision were 3.9%, 1.3%, 6.9%, and 5.1% for PT, APTT, fibrinogen, and AT, respectively. At 4 degrees C, citrated specimens were stable up to 8 hr for whole blood and 36 hr for plasma, except for APTT, which increased slightly (<1 sec). Nonparametric reference intervals determined in citrated plasma from 139 healthy fasting purebred dogs were 6.9-8.8 sec, 13.1-17.2 sec, 1.24-4.30 g/l, and 104-188% for PT, APTT, fibrinogen, and AT, respectively. Based on Passing-Bablok comparison between STA Satellite and STA-R Evolution(R) using 60 frozen specimens from a canine plasma bank, the corresponding reference intervals were transferred to the STA-R Evolution: 7.1-9.2 sec, 12.9-17.3 sec, 1.20-4.43 g/l, and 94-159% for PT, APTT, fibrinogen, and AT, respectively.

Reference values: a review.

Reference values are used to describe the dispersion of variables in healthy individuals. They are usually reported as population-based reference intervals (RIs) comprising 95% of the healthy population. International recommendations state the preferred method as a priori nonparametric determination from at least 120 reference individuals, but acceptable alternative methods include transference or validation from previously established RIs. The most critical steps in the determination of reference values are the selection of reference individuals based on extensively documented inclusion and exclusion criteria and the use of quality-controlled analytical procedures. When only small numbers of values are available, RIs can be estimated by new methods, but reference limits thus obtained may be highly imprecise. These recommendations are a challenge in veterinary clinical pathology, especially when only small numbers of reference individuals are available.