Electrocardiographic Parameters in the Normal Lactating Holstein Cow

Electrocardiographic parameters in the normal lactating Holstein cow have been measured, computed and analyzed. The study was conducted on 32 animals of a mean age of 4.7 years. The recordings of the 12 leads (I, II, III, aVR, aVL, aVF, CV₆LU, CV₆LL, CV₆RL, CV₆RU, V₁₀ and base-apex) were made with a three channel electrocardiograph calibrated at 20 mm/mV and 25 mm/s. Conduction parameters, waves, intervals and segments have been measured. The recordings were analyzed as to shape, polarity and amplitude of the P and T waves and the components of the QRS complex. The results are discussed in respect to the morphophysiological characterestics of the bovine heart.     

ECHOCARDIOGRAPHIC REFERENCE VALUES IN WHIPPETS

The aim of the study was to establish reference echocardiographic values for whippets, to compare these values with previously published reference values for the general dog population, and to determine whether there is an influence of gender and breeding lines on echocardiographic measurements. Echocardiographic parameters from 105 apparently healthy whippets without cardiac symptoms were used to establish reference values for the breed and to compare these values with two previously reported reference ranges. The coefficients of the allometric equation Y= aM(b), useful to reconstruct normal M-mode and two-dimensional average values for whippets of varying weights, were calculated, as well as the lower and upper limits of the 95% prediction interval. First, we found that whippets have a significantly larger left ventricular diameter, increased left ventricular wall, and interventricular septum thickness than expected, in diastole as well as in systole. Fractional shortening was significantly lower than the reference value. Second, comparing males and females, taking body weight differences into account, females had a significantly larger left ventricular diameter in diastole and systole. Minor differences were found between racing and show pedigree dogs. In conclusion, the results of this study confirm that breed-specific reference values are needed in echocardiography. In whippets, the values found in this study can be used as references in order to avoid overinterpretation of cardiac dilation, hypertrophy, and/or decreased contractility in these dogs.     

The normal electrocardiogram of the unanaesthetized competition "Spanish Pouler" pigeon (Columba livia gutturosa)

This investigation was carried out on 64 healthy adult competition pigeons (Spanish Poulers) to determine reference values of electrocardiographic parameters in standard lead II; a comparative study between males and females was also performed to find changes in the electrocardiographic patterns related to sex. P wave was positive and monophasic; PR segment depression was present in 64% of records; the QRS pattern obtained was in most cases of the rS type, followed by the QS configuration. ST slurring (absence of ST) was observed in 47% of records and the mean electrical axis was in all cases negative. Statistically significant differences related to sex were found for P-wave, R-wave and T-wave amplitudes, showing the males have greater amplitudes than females, associated with the increase of cardiac tissue mass. No sex-related differences were found in heart rate and mean electrical axis.     

Evaluation of six-lead electrocardiograms obtained from dogs in a sitting position or sternal recumbency

OBJECTIVE: To compare 6-lead ECG traces in clinically normal conscious dogs in a sitting position and sternal recumbency to that of right lateral recumbency. ANIMALS: 31 healthy dogs with no history of cardiac disease. PROCEDURE: Six-lead ECGs were recorded for dogs in right lateral recumbency, a sitting position, and sternal recumbency. Q-, R-, and S-wave amplitudes as well as QRS-complex duration were measured in all leads. Additionally, P-wave amplitude and duration, PR interval, ST-segment elevation or depression, and OT interval were measured in lead II. RESULTS: Compared with measurements in right lateral recumbency, the sitting position resulted in increased Q-wave amplitude (lead III), increased R-wave amplitude (leads I and aVL), decreased R-wave amplitude (leads III and aVF), increased S-wave amplitude (lead aVR), decreased S-wave amplitude (lead aVL), increased P-wave amplitude (lead II), and a leftward shift in the mean electrical axis. Compared with measurements in right lateral recumbency, sternal recumbency resulted in decreased Q-wave amplitude (leads I, II, and aVF), increased R-wave amplitude (leads 11, III, and aVF), decreased R-wave amplitude (lead aVR), increased S-wave amplitude (lead aVR), increased P-wave amplitude (lead II), and decreased ST-segment depression (lead II). Compared with right lateral recumbency, the sitting position or sternal recumbency did not result in significant differences in PR interval, QT interval, or QRS-complex duration. CONCLUSIONS AND CLINICAL RELEVANCE: Significant changes are found in ECG measurements in the sitting position and sternal recumbency, compared with right lateral recumbency. In dogs, many ECG reference range values for right lateral recumbency are not valid for ECGs obtained in the sitting position or sternal recumbency.     

Biologic variability of N-terminal pro-brain natriuretic peptide in healthy dogs and dogs with myxomatous mitral valve disease

Introduction

To determine the biologic variability of N-terminal pro-brain natriuretic peptide (NTproBNP) in healthy dogs and dogs with various stages of myxomatous mitral valve disease (MMVD).

Biological variability of C-reactive protein and specific canine pancreatic lipase immunoreactivity in apparently healthy dogs

Background: C‐reactive protein (CRP) and specific canine pancreatic lipase immunoreactivity (Spec cPL) are biomarkers of generalized or nonspecific inflammation and pancreatic inflammation in dogs, respectively. The extent of inter‐ and intraindividual variation over time of these analytes is not well defined in dogs. The minimal critical difference for sequential determinations of these markers (ie, the smallest change necessary to represent physiological change rather than biological variation), has not been defined. Objectives: To determine the inter‐ and intraindividual variability (CV_G and CV_I) and minimal critical difference for sequential determinations of serum CRP and Spec cPL concentrations in apparently healthy dogs. Animals: Eleven apparently healthy dogs owned by staff or students at a veterinary teaching hospital. Methods: Blood was collected repeatedly at varying intervals over 12 weeks. CRP and Spec cPL concentrations were determined with commercially available assays. Indices of inter‐, intraindividual, and assay variability and 1‐sided minimal critical differences for sequential concentrations were calculated. Results: For CRP, CV_G was 90.8%, CV_I was 115.5%, and the analytical variability (CV_A) was 6.3%; the index of individuality was 0.74, and 1‐sided critical difference was 269.9%. For Spec cPL, CV_G= 49.48%, CV_I= 193.8%, CV_A= 8.4%, index of individuality = 0.24, and 1‐sided critical difference was 452.6%. Conclusions and Clinical Importance: A population‐based reference range is appropriate for Spec cPL, but questionable for CRP in dogs. Large changes in serial measurements of Spec cPL are necessary to infer clinical importance, more modest changes in CRP are likely to be meaningful.     

Effect of body position on the 6-lead ECG of dogs

ECGs recorded from dogs show characteristic morphology and changes in morphology with various disease states. These changes are determined by comparing individual recordings to reference ranges established from recordings obtained from normal dogs in right lateral (RL) recumbency. Using these reference ranges for ECGs recorded from dogs in other positions may not be valid. We compared ECG complexes from 39 normal dogs obtained in RL, left lateral (LL), and standing (ST) body positions. ECGs from dogs in ST position showed increased Q-wave and R-wave amplitudes in leads I and II, increased R-wave and S-wave amplitudes in leads aVR and aVL, and decreased R-wave and S-wave amplitudes in lead III when compared with recordings obtained in RL position. ECGs from dogs in LL position showed increased R-wave amplitude in leads II, III, and aVF and S-wave amplitude in lead aVL but decreased R-wave amplitude in lead aVR when compared with recordings obtained in RL position. The mean electrical axis (MEA) shifted to the left in ST position but remained within the normal range in LL position. We determined that both a change in the relative position of the recording electrodes with respect to the heart as well as a change in intrathoracic cardiac position contributed to these changes. P-wave amplitude, P-R and S-T intervals, and QRS complex durations remained unaltered by changes in body position. Our findings indicate that ECGs of dogs recorded in RL, LL, and ST positions yield dramatically different results, and investigators should use position-specific reference ranges to minimize potential misinterpretation of ECG results.     

Electrocardiographic parameters in the clinically healthy Zamorano-leones donkey

Limited information exists regarding electrocardiographic parameters in clinically healthy donkeys. The study was carried out in 75 healthy adult animals (40 females and 35 males) using the Einthoven standard II and base-apex leads. The P wave showed usually a bifid shape deflection. The QRS complex of the donkeys appeared in several forms: QR and R were the most frequent in limb lead II, and QS and QR in the base-apex lead. Most T waves presented a simple negative configuration in lead II and biphasic shape in the base-apex one. Mean heart rate value was 52 beats per minute. The direction of the QRS vector in lead II had a mean value of 91.4°. We observed a lack of detected arrhythmias. Statistically significant differences were observed between sexes for several parameters. The electrocardiogram of Zamorano-leones donkey differs in several duration, amplitude and morphologic parameters from that of several breeds of horses and donkeys. This fact justifies obtaining values for a specific breed against which to compare values for the same breed.     

Patient characteristics influencing the variability of distributed parameter‐based models in DCE‐CT kinetic analysis

Kinetic parameter variability may be sensitive to kinetic model choice, kinetic model implementation or patient‐specific effects. The purpose of this study was to assess their impact on the variability of dynamic contrast‐enhanced computed tomography (DCE‐CT) kinetic parameters. A total of 11 canine patients with sinonasal tumours received high signal‐to‐noise ratio, test‐double retest DCE‐CT scans. The variability for three distributed parameter (DP)‐based models was assessed by analysis of variance. Mixed‐effects modelling evaluated patient‐specific effects. Inter‐model variability (CV_inter) was comparable to or lower than intra‐model variability (CV_intra) for blood flow (CV_inter:[4–28%], CV_intra:[28–31%]), fractional vascular volume (CV_inter:[3–17%], CV_intra:[16–19%]) and permeability‐surface area product (CV_inter:[5–12%], CV_intra:[14–15%]). The kinetic models were significantly (P<0.05) impacted by patient characteristics for patient size, area underneath the curve of the artery and of the tumour. In conclusion, DP‐based models demonstrated good agreement with similar differences between models and scans. However, high variability in the kinetic parameters and their sensitivity to patient size may limit certain quantitative applications.     

The effects of intravenous ciprofloxacin on the electrocardiogram of healthy dogs

The purpose of this study was to evaluate the electrocardiographic effects of single intravenous dose of ciprofloxacin in dogs. Ten adult cross-breed dogs of both sexes were selected as the sample population. Baseline electrocardiographic values were recorded just before drug administration. Then the dogs received intravenous infusion of ciprofloxacin (10 mg/kg) over the fifteen minutes. The ECGs recorded at 15, 30, 60 and 120 minutes after ciprofloxacin administration. The ECG measurements of heart rate, PR interval, QRS interval, ST segment, T-wave amplitude and QT interval were taken from lead II. There was a small but significant increase in the longest QT intervals over baseline at T₆₀ (P = 0.041). The mean PR intervals, QTc intervals, JT intervals, ST segment, T-wave amplitude did not differ significantly before and after ciprofloxacin except for JT intervals at T₆₀ (P = 0.041). At this measurement point_, there was an increased QT interval value of 0.02 second or 9.51 % in comparison to the baseline. In Conclusions, Only minor QT intervals changes were observed after ciprofloxacin injection. Despite the occurrence of ECG changes following intravenous ciprofloxacin administration neither dangerous rhythm disturbances nor serious ECG changes were seen in this study.     

Effects of levomepromazine and different desflurane concentrations upon electrocardiographic variables in dogs

Objectives To investigate the effects of levomepromazine and different desflurane concentrations upon electrocardiographic variables. Animals Twenty adult mongrel dogs of both sexes weighing 6–28 kg. Methods Dogs were divided into two groups of 10 animals. Group 1 received 1 mg kg^?1 IV of levomepromazine and 15 minutes later anesthesia was induced with propofol (3 mg kg^?1 IV). Desflurane end‐tidal concentration was set at 1.6 MAC. After 30 minutes at this concentration, measurements were taken and the end‐tidal concentration was reduced to 1.4 MAC. Thereafter, it was reduced to 1.2 and then 1.0 MAC at 15‐minute intervals. The same procedure was followed for group 2, except that levomepromazine was replaced with 0.2 mL kg^?1 of 0.9% saline solution and more propofol was needed for induction (7 mg kg^?1). The animals' body temperature was maintained between 38.3 and 39 °C using a heating pad. The electrocardiographic tracing was obtained from lead II throughout the experimental period. The measurements were taken immediately before the administration of levomepromazine or placebo (T₁), 15 minutes after pre‐medication (T₂) and 30 minutes after the establishment of 1.6 MAC (T₃). The other measurements were made at the concentrations of 1.4, 1.2, and 1.0 MAC, respectively (T_4?6). The numerical data were submitted to analysis of variance plus F‐test (p < 0.05). Results The dogs that received levomepromazine had a decrease in heart rate. However, in both groups it increased with desflurane administration. Levomepromazine, in association with desflurane, did not induce significant electrocardiographic changes, and all mean values (except P‐wave duration) were within the reference range for this species. Conclusions and clinical relevance This study documented that levomepromazine, in association with desflurane, does not induce significant changes in electrocardiographic variables, suggesting that this drug combination has minimal effect on myocardial conduction.     

Serum thyroid hormone concentrations and thyroglobulin autoantibodies in trained and non-trained healthy whippets

Numerous factors including non-thyroidal systemic diseases and drug administration can significantly alter canine thyroid function test results. Furthermore, the importance of breed specific variations has probably been underestimated. In this study, total thyroxine (TT4), free thyroxine (FT4), canine endogenous thyroid stimulating hormone (cTSH) serum concentrations and thyroglobulin autoantibodies (TgAA) were determined in a population of healthy whippets and compared to a control group of different breeds. Mean TT4 values were significantly lower in the whippets but no significant differences were seen between whippets and control dogs for FT4 and for cTSH. The prevalence of serum TgAA in the whippets was 2%, and this was not significantly different from the controls. The results suggest a breed variation for TT4, but not for FT4, cTSH and TgAA serum concentrations in whippets. Serum thyroid hormone concentrations were also compared between trained and non-trained whippets and it was concluded that regular training did not seem to have any significant influence.     

Physiological shift of the ventricular mean electrical axis in healthy French Bulldogs: a retrospective electrocardiographic analysis of 80 healthy dogs

Introduction/objectivesWhether a brachymorphic conformation may lead to electrocardiographic peculiarities diverging from generic reference intervals (RIs) cited in textbooks remains to be established. Therefore, this study aimed at evaluating electrocardiographic variables in one of the most common brachymorphic breed, namely the French Bulldog (FB).Animals, materials and methodsMedical records were retrospectively reviewed to identify healthy FBs ≥1-year-old that underwent an electrocardiogram. The Mann–Whitney U test or the Student's t-test was used to compare continuous variables among male and female dogs, while the χ² test was used for categorical variables. Spearman's correlation coefficients between electrocardiographic measurements and age and body weight were also calculated. Moreover, electrocardiographic RIs were determined.ResultsEighty healthy FBs were enrolled; their electrocardiographic variables fitted with generic RIs, with the exception of the QRS-complex mean electrical axis (QRS-MEA). The median QRS-MEA value was 43.5° (from −18° to +90°). A QRS-MEA shift was found in 24/80 (30%) dogs; in all cases, it was a left shift (median 26°, from −18° to +39°). Specifically, 20 dogs showed a slight left shift (from +39° to +14°), while four dogs showed a marked one (from +9° to −18°). No meaningful differences were found when comparing electrocardiographic variables between males and females. No significant correlations between electrocardiographic variables and age or body weight were found, with the exceptions of the P-wave amplitude, PQ-interval duration and QT-interval duration.ConclusionsHealthy FBs can present a left shift of QRS-MEA. These data should be considered when interpreting FBs’ electrocardiograms.     

Morphology and amplitude values of the electrocardiogram of Spanish-bred horses of different ages in the Dubois leads system

The aim of this work was to record the modifications of the form and amplitude of the electrocardiographic tracings during growth using the Dubois system and to study its sensibility to these physiological changes. This work was carried out on 179 healthy, young and adult Spanish-bred horses (98 females and 81 males). One electrocardiogram (ECG) was obtained from each horse using the Dubois leads system. The bifid shape deflection of the P wave was generally more frequent than the simple one in animals at 4 months of age or older. Amplitudes of the P2 component and of the simple positive wave presented significant differences (p < 0.01) between the age groups studied: animals up to 3 months in age and older than 2 years of age (highest amplitudes), and the rest of the animals (lowest amplitudes). Significant variations (p < 0.05) were found for the QS amplitude between animals of 1 month of age, and all the other groups. The multiple range analysis did not define a clear distribution of age groups for the amplitude of the T wave. It may therefore be concluded, that in the Spanish-bred horse up to 1 month of age, the form and amplitude of the QRS complex in the Dubois leads system differ from those of older animals. Thus, this study shows the sensibility of the Dubois leads system for detecting the electrocardiographic changes related to the growing process in the Spanish-bred horse. In addition, it provides standard values of electrocardiographic parameters in the Spanish-bred horse at different stages of growth.     

Haemodynamic, electrocardiographic, electrophysiologic and pharmacokinetic activity of 4'-hydroxypropranolol in dogs

We determined the haemodynamic, electrocardiographic and electrophysiologic effects, and the pharmacokinetic properties of 4′-hydroxypropranolol (4′-OHP) by conducting three different experiments in dogs. In experiment 1 the plasma concentrations of 4′-OHP (mg/kg, i.v.) in pentobarbital anaesthetized dogs were determined by HPLC and pharmacokinetic parameter values were estimated. The terminal elimination half-life (t1/2) for 4′-OHP was 69.4 min, the apparent volume of distribution (V_d) was 3.39 L/kg and the total clearance (Cl_t) was 53.6 mL/min·kg. These data were subsequently used to calculate the loading and maintenance doses of 4′-OHP required to produce targeted steady-state plasma concentrations for 4′-OHP of 30, 60, 120, 240 and 480 ng/mL. In experiment 2 the haemodynamic and electrocardiographic effects for target plasma concentrations of 4′-OHP were determined in two groups of pentobarbital anaesthetized dogs, and beta-blocking activity was assessed by infusion or bolus doses of isoproterenol. The haemodynamic and electrocardiographic effects of the target plasma concentrations (30, 60, 120 ng/mL) of 4′-OHP were first determined in seven pentobarbital anaesthetized dogs (Group 1). Beta blocking activity was assessed by the infusion of 0.1 μg/kg/min isoproterenol. The infusion of 4′-OHP produced dose dependent decreases in heart rate, cardiac output, dP/dt_max, mean arterial pressure and left ventricular diastolic pressure. The PR interval of the lead II electrocardiogram increased and the QT_c interval decreased. These haemodynamic and electrocardiographic changes became apparent at plasma 4′-OHP concentrations equal to or greater than 30 ng/mL. Plasma concentrations of 4′-OHP equal to or greater than 30 ng/mL prevented the haemodynamic and electrocardiographic effects of isoproterenol infusion. In group 2 dogs, (seven dogs) the haemodynamic and electrocardiographic effects of target plasma concentrations (30, 60, 120, 240, 480 ng/mL) of 4′-OHP were evaluated and beta-blocking activity was assessed by the i.v. bolus administration of 1 and 4 μg/kg of isoproterenol. The infusion of 4′-OHP produced haemodynamic and electrocardiographic changes similar to those in group 1 dogs. In addition, the QRS duration of the electrocardiogram increased at plasma concentrations of 4′-OHP equal to or greater than 240 ng/mL. The haemodynamic and electrocardiographic effects of i.v. bolus dose administrations of 1 and 4 μg/kg isoproterenol were abolished by plasma concentrations of 4′-OHP equal to or greater than 240 ng/mL. In experiment 3 we determined the electrophysiologic effects of 10^?9 to 10^?5 mmol/L 4′-OHP on Tyrodes superfused bundles of canine Purkinje fibres. Action potential duration and the effective refractory period decreased at superfusate concentrations of 4′-OHP equal to or greater than 10^?7 mmol/L. Action potential overshoot, action potential total amplitude, the rate of rise of phase O (dV/dt) and spontaneous rate decreased at superfusage concentrations of 4′-OHP equal to or greater than 800 ng/mL. These studies demonstrate that: 1) 4′-OHP produces haemodynamic, electrocardiographic and electrophysiologic effects similar to those of other beta-blocking drugs in pentobarbital anaesthetized dogs; 2) the haemodynamic and electrocardiographic effects produced by 4′-OHP are     

Improvement and validation of the method to determine neutral detergent fiber in feed

To improve the performance of the analytical method for neutral detergent fiber in feed with heat‐stable α‐amylase treatment (aNDFom), the process of adding heat‐stable α‐amylase, as well as other analytical conditions, were examined. In this new process, the starch in the samples was removed by adding amylase to neutral detergent (ND) solution twice, just after the start of heating and immediately after refluxing. We also examined the effects of the use of sodium sulfite, and drying and ashing conditions for aNDFom analysis by this modified amylase addition method. A collaborative study to validate this new method was carried out with 15 laboratories. These laboratories analyzed two samples, alfalfa pellet and dairy mixed feed, with blind duplicates. Ten laboratories used a conventional apparatus and five used a Fibertec^® type apparatus. There were no significant differences in aNDFom values between these two refluxing apparatuses. The aNDFom values in alfalfa pellet and dairy mixed feed were 388 g/kg and 145 g/kg, the coefficients of variation for the repeatability and reproducibility (CV_r and CV_R) were 1.3% and 2.9%, and the HorRat values were 0.8 and 1.1, respectively. This new method was validated with 5.8% uncertainty (k = 2) from the collaborative study.     

Arterial blood gas parameters of normal foals born at 1500 metres elevation

Reasons for performing study: Arterial blood gas analysis is widely accepted as a diagnostic tool to assess respiratory function in neonates. To the authors' knowledge, there are no published reports of arterial blood gas parameters in normal neonatal foals at altitude. Objective: To provide information on arterial blood gas parameters of normal foals born at 1500 m elevation (Fort Collins, Colorado) in the first 48 h post partum. Hypothesis: Foals born at 1500 m will have lower P_aO₂ and P_aCO₂ than foals born at sea level due to low inspired oxygen and compensatory hyperventilation occurring at altitude. Methods: Sixteen foals were studied. Arterial blood gas analysis was performed within 1 h of foaling and subsequent samples were evaluated at 3, 6, 12, 24 and 48 h post partum. Data were compared to those previously reported in healthy foals born near sea level. Results: Mean P_aO₂ was 53.0 mmHg (7.06 kPa) within 1 h of foaling, rising to 67.5 mmHg (9.00 kPa) at 48 h post partum. P_aCO₂ was 44.1 mmHg (5.88 kPa) within one hour of foaling, falling to 38.3 mmHg (5.11 kPa) at 48 h. Both P_aO₂ and P_aCO₂ were significantly lower in foals born at 1500 m elevation than those near sea level at several time points during the first 48 h. Conclusions and potential relevance: Foals at 1500 m elevation undergo hypobaric hypoxia and compensatory hyperventilation in the first 48 h. Altitude specific normal arterial blood values are an important reference for veterinarians providing critical care to equine neonates.     

Comparative electrocardiography in four species of macaws (genera Anodorhynchus and Ara)

Electrocardiograms (ECGs) were recorded during isoflurane anaesthesia from 52 macaws of four species of the genera Anodorhynchus and Ara in order to establish electrocardiographic reference values. The birds examined were clinically healthy macaws of the following species: hyacinth macaw (HM; Anodorhynchus hyacinthinus, n = 14); green-winged macaw (GWM; Ara chloroptera, n = 11); blue-throated macaw (BTM; Ara glaucogularis, n = 15); and red-fronted macaw (RFM; Ara rubrogenys, n = 12). All ECGs were recorded using a paper speed of 50 mm/s and a calibration of 10 mm = 1 mV. Significant differences were determined between species for the heart rate, duration and amplitude of the P wave, amplitude of the T wave, and amplitude of the QRS complex, specially comparing the RFM to the other macaw species. No significant differences were found between two species of similar body weight: the HM and the GWM.     

Comparison of bovine hematology reference intervals from 1957 to 2006

Background: The most commonly used bovine hematology reference intervals were published in 1965. We found the results from healthy cattle in 2001 differed from those in many ways. Discovery of the original laboratory book used to calculate the 1965 values gave us the opportunity to evaluate whether hematology values of healthy cattle have changed over time. Objective: The purpose of this study was to establish hematology reference intervals for Holstein cows, compare selected hematologic results with similar population data from 1957, and compare these reference intervals with those of other North American veterinary schools and published values. Methods: Reference intervals were developed in 2001 using clinically healthy, bovine leukemia virus‐negative, mid‐lactation Holstein cows. Selected parts of the hemograms and neutrophil:lymphocyte (N:L) ratio were compared with those from healthy, age‐matched Holstein cows evaluated in 1957. Bovine reference intervals were solicited from clinical pathology laboratories in North American veterinary colleges and analyzed for population characteristics and method of analysis. Results: Between 1957 and 2001, mean neutrophil counts increased significantly, whereas lymphocyte, monocyte, and eosinophil counts and hemoglobin concentration decreased significantly. Mean N:L ratio increased significantly to 1.17. Most surveyed laboratories were using the 1965 reference intervals. Two other institutions that had developed reference intervals after 2000 had results similar to ours. Conclusions: Continued use of older bovine hematology reference intervals could lead to misinterpretation of within‐reference neutrophil counts as neutrophilia and under‐recognition of neutropenia, eosinophilia, monocytosis, or lymphocytosis. Use of N:L>1 as evidence of inflammation should be discontinued or used with great caution.