Repeat patient testing-quality control compared to commercial quality control material for the Sysmex XT-2000iV hematology analyzer in a multi-site veterinary laboratory.

BACKGROUND: Quality control material (QCM) for hematology in veterinary laboratories is limited, and repeat patient testing quality control (RPT-QC) is an alternative method using excess matrix-specific samples. OBJECTIVES: This study aimed to determine if median differences between RPT-QC analyses for each time interval for RBC, HGB, HCT, and WBC were the same, determine if unified RPT-QC limits can be applied to a network of veterinary laboratories, compare the performance of RPT-QC to commercial QCM for the reference analyzer and evaluate the experience over a 4 month period and design, improve and implement an automated spreadsheet for RPT-QC data management. METHODS: The potential to unify individual analyzer RPT-QC limits for red blood cells (RBC), hematocrit (HCT), hemoglobin (HGB), and white blood cells (WBC) on multi-site Sysmex XT-2000-iV analyzers was explored by a difference of means test and confidence interval determination for the median difference for each network analyzer in comparison to the network reference analyzer. User experience of an automated RPT-QC data management Excel spreadsheet was collected by user feedback during monthly meetings. Numbers of out-of-control results and the root causes for these for RPT-QC were compared against those of a commercial QCM over a 4-month period. RESULTS: Differences between individual analyzer RPT-QC limits were too large to allow for unification of network limits. The automated spreadsheet successfully highlighted out-of-control events for RPT-QC. Trends or shifts were more frequent for commercial QCM based on observed performance and a 1-2.5 s QC rule than for RPT-QC. Following routine troubleshooting, RPT-QC out-of-control events were resolved with an alternative RPT-QC sample indicating random error associated with excessive deterioration. Use of an automated spreadsheet for recording RPT-QC, documentation and troubleshooting of out-of-control events, and collating monthly summary calculations were considered an asset in laboratory quality management. CONCLUSIONS: RPT-QC can be successfully implemented and integrated into a multi-site veterinary laboratory. Individual analyzer RPT-QC limit generation is recommended. The deterioration of commercial QCM caused shifts or trends in QC results, which initiated more repeat analyses and investigations than did RPT-QC.

Veterinary echocardiographers' preferences for left atrial size assessment in cats: the BENEFIT project.

INTRODUCTION/OBJECTIVES: Veterinary echocardiographers' preferences for left atrial (LA) size assessment in cats have not been systematically investigated. The primary aim of this prospective exploratory study was to investigate echocardiographers' preferences concerning LA size assessment in cats. A secondary aim was to investigate echocardiographers' preferences for assessing LA size in subgroups based on geographic, demographic, and professional profiles. ANIMALS, MATERIALS, AND METHODS: An online survey instrument was designed, verified, and distributed globally to veterinary echocardiographers. RESULTS: A total of 655 veterinary echocardiographers from six continents and 54 countries, working in specialty practice (56%) and in general practice (38%), provided data. Linear two-dimensional (2D) technique was favored by most echocardiographers (n = 612) for LA size assessment. Most commonly, respondents combined linear 2D with subjective assessment (n = 227), while 209 used linear 2D-based methods alone. Most echocardiographers using linear 2D-based methods preferred the right parasternal short-axis view and to index the LA to the aorta (Ao). Approximately 10% of the respondents obtained LA dimensions from a right parasternal long-axis four-chamber view. Approximately one-third of echocardiographers that made linear measurements from 2D echocardiograms shared the same preferences regarding cat position, acquisition view, indexing method and time point identification for the LA measurement. The responses were comparably homogeneous across geographic location, level of training, years performing echocardiography, and type of practice. DISCUSSION/CONCLUSION: Most veterinary echocardiographers assessed LA size in cats using linear 2D echocardiography from a right parasternal short-axis view, and indexed LA to Ao. Respondents' preferences were similar over geographic, demographic, and professional backgrounds.

Veterinary echocardiographers' preferences for left atrial size assessment in dogs: the BENEFIT project.

INTRODUCTION/OBJECTIVES: Veterinary echocardiographers' preferences for left atrial (LA) size assessment in dogs have never been systematically investigated. The primary aim of this international survey study was to investigate echocardiographers' preferences for LA size assessment in dogs. The secondary aim was to investigate echocardiographers' preferences for assessing LA size in subgroups based on geographic, demographic, and professional profiles. ANIMALS, MATERIALS, AND METHODS: An online survey instrument was designed, verified, and distributed globally to the veterinary echocardiographers. RESULTS: A total of 670 echocardiographers from 54 countries on six continents completed the survey. Most echocardiographers (n = 621) used linear two-dimensional (2D)-based methods to assess LA size, 379 used subjective assessment, and 151 used M-mode-based methods. Most commonly, echocardiographers combined linear 2D-based methods with subjective assessment (n = 222), whereas 191 used linear 2D-based methods alone. Most echocardiographers (n = 436) using linear 2D-based methods preferred the right parasternal short-axis view and indexed the LA to the aorta. Approximately 30% (n = 191) of the echocardiographers who performed linear measurements from 2D echocardiograms shared the same preferences regarding dog position, acquisition view, indexing method, and identification of the time-point used for the measurement. The responses were comparably homogeneous across geographic location, training level, years of performing echocardiography, and type of practice. DISCUSSION/CONCLUSION: Most veterinary echocardiographers assessed LA size in dogs using linear 2D echocardiography from a right parasternal short-axis view, and by indexing the LA to the aorta. The respondents' preferences were similar across geographic, demographic, and professional backgrounds.

Differences in Left Ventricular Enlargement Secondary to Chronic Volume Loading Between English Springer Spaniels and Two Similar Sporting Breeds.

INTRODUCTION: English springer spaniels have larger, rounder ventricles than most other breeds. How this geometry impacts responses to volume overload remains unknown. We compared left ventricular size between English springer spaniels and two similarly sized sporting breeds (Border collies and Labrador retrievers) in naturally occurring chronic left ventricular volume loading conditions (mitral regurgitation and patent ductus arteriosus [PDA]) to examine whether differences in remodelling responses exist between these breeds. ANIMALS, MATERIALS AND METHODS: We searched records for cases of mitral regurgitation and PDA in three breeds. We recorded age, sex, presence of congestive heart failure (CHF), body weight and specific echocardiographic variables. We compared normalised measures of left ventricular size between breeds. Cases with CHF were further examined as a separate group. RESULTS: One-hundred-and-ninety-one dogs were included: 110 with degenerative mitral valve disease, 42 with mitral dysplasia and 39 with PDA. One third of all cases had CHF. All measures of left ventricular size were larger in English springer spaniels in mitral regurgitation cases (P<0.001), whereas PDA cases did not differ. English springer spaniels with PDA resulting in CHF had larger systolic dimensions and volumes than similarly affected non-English Springer Spaniel dogs (P=0.003). CONCLUSIONS: English springer spaniels have greater left ventricular dimensions when exposed to chronic mitral regurgitation, compared with Border collies and Labrador retrievers, but not when exposed to volume overload from a PDA. English springer spaniels differ in their left ventricular morphology from two other sporting breeds, supporting previous studies that they have a unique cardiac morphotype.

Proposed limits for ordinal echocardiographic estimates of left atrial enlargement in dogs.

OBJECTIVE: To propose echocardiographic left-atrial-to-aortic ratio (LA:Ao) limits for defining ordinal categories of left atrial (LA) enlargement in dogs. ANIMALS, MATERIALS AND METHODS: Right parasternal short-axis echocardiographic images from 33 dogs with various degrees of LA enlargement. Right parasternal short-axis and long-axis echocardiographic measurements from 238 healthy dogs. Images were duplicated and randomized. Duplicate images contained a LA:Ao estimate. Participants categorized the LA in each image into one of four categories: normal, mildly, moderately or severely enlarged. Distributions of categorization were compared between cardiologists and non-cardiologists. Intra-observer intra-study and inter-study agreement were examined. Effect of measurement was evaluated on agreement between participants. A parametric estimate of LA enlargement was calculated for both short-axis and long-axis views. RESULTS: Cardiologists and non-cardiologists provided similar distributions of LA size estimates, and showed similarly high intra-observer agreement (kappa = 0.84). Having a measurement provided with the image increased agreement for categorizing LA as normal or mildly enlarged (P<0.001). Parametric and consensus-based approaches provided similar limits for categorizing left atrial size in the right parasternal short-axis view - normal = LA:Ao < 1.6, mildly enlarged = 1.6 < LA:Ao < 1.9, moderately enlarged = 1.9 < LA:Ao < 2.3, severely enlarged = LA:Ao ≥ 2.3. A parametric approach for the right parasternal long-axis view provided the following: normal = LA:Ao < 2.1, mildly enlarged = 2.1 < LA:Ao < 2.5, moderately enlarged = 2.5 < LA:Ao < 2.7, severely enlarged = LA:Ao ≥ 2.7. CONCLUSIONS: Participants mostly classified LA sizes into four ordinal categories that corresponded to the aforementioned limits. Clinicians estimating LA size in early diastole can use these limits to increase inter-observer agreement when identifying LA enlargement.

Two-dimensional echocardiographic estimates of left atrial volumes obtained from two different views in dogs are similar but not interchangeable.

Left atrial (LA) volumes using a monoplane Simpson's Method of Discs (SMOD) can be obtained from the right parasternal long axis four-chamber (RPLA) or from the left apical four-chamber (LA4C) views in dogs; however, little information exists regarding the agreement of LA volume estimates using a SMOD on images obtained from LA4C and RPLA views. Therefore, we sought to examine the agreement between the two methods of obtaining LA volumes in a heterogenous population of healthy and diseased dogs. Additionally, we compared the LA volumes obtained by SMOD with estimates obtained from simple cube or sphere volume formulae. Archived echocardiographic examinations were retrieved and, where both RPLA and LA4C views were adequately recorded, included in the study. We obtained measurements from 194 dogs that were either apparently healthy (n = 80) or had various cardiac diseases (n = 114). The LA volumes of each dog was measured using a SMOD, from both views, in systole and diastole. Estimates of LA volumes obtained from simple cube or sphere volume formulae from RPLA-derived LA diameters were also calculated. We then used Limits of Agreement analysis to determine agreement between the estimates obtained with each view, and those calculated from linear dimensions. The two methods obtained by SMOD provided similar estimates for both systolic and diastolic volumes but did not agree sufficiently to be interchangeable. The LA4C view often slightly underestimated the LA volumes at small LA sizes and overestimated the LA volumes at large LA sizes compared to RPLA method, with increasing disagreement as the LA size increased. Estimates based on cube method overestimated volumes compared to both SMOD methods, whereas those based on sphere method performed reasonably. Our study suggests that monoplane volume estimates from the RPLA and LA4C views are similar but not interchangeable. Clinicians can also perform a rough estimate of LA volumes using RPLA-derived LA diameters to calculate the sphere volume.

Use of urinalysis during baseline diagnostics in dogs and cats: an open survey.

OBJECTIVES: To describe how veterinarians utilise and perform urinalyses for dogs and cats. MATERIALS AND METHODS: A survey, developed and distributed through the Veterinary Information Network, enlisted veterinarians who perform urinalyses for dogs and cats. Participants were directed to question banks based on whether urinalyses were performed in-house, by an outside diagnostic laboratory, or using an in-house automated instrument. Participants using multiple methods were directed to questions that related to the chosen methods. RESULTS: A total of 1059 predominantly first-opinion clinicians from the USA and Canada completed the survey. Participants performed urinalyses much less frequently than blood work during a routine examination. The most common factors preventing participants from performing a urinalysis with blood work included clients' financial constraints, difficulty obtaining urine and lack of perceived diagnostic need. The most common reasons for submission to a diagnostic laboratory included efficiency, more trusted results and convenience. Speed of obtaining results was the most common reason for performing urinalyses in-house. Of the participants who performed in-house urinalyses, fewer always performed a manual sediment examination (79%) as compared with urine-specific gravity (99%) and manual dipstick (87%). CLINICAL SIGNIFICANCE: This survey documents that urinalysis is often not used in senior patients as recommended by recent clinical guidelines for dogs and cats which can result in decreased diagnosis and impaired management of subclinical disease. There is significant variability in urinalysis methods despite veterinary guidelines promoting standardisation, and this could lead to inaccurate results.

The ACVIM consensus statement definition of left ventricular enlargement in myxomatous mitral valve disease does not always represent left ventricular enlargement.

OBJECTIVE: To determine how frequently the current criteria for left ventricular enlargement in dogs misclassify healthy dogs as having left ventricular enlargement; to examine the effect of breed on diastolic left ventricular normalized dimensions (LVIDDN); to propose appropriate scaling exponents and reference limits for dogs. ANIMALS: Echocardiographic data from 1,124 healthy adult dogs, including 454 dogs weighing <20 kg. METHODS: We calculated power regression parameters (allometric scaling), including exponents and proportionality constants, for various subsets of the dogs (all dogs, dogs < 20 kg, generic dogs, and individual breeds with >10 observations) and derived upper reference limits for LVIDDN. We determined the proportions of dogs that would be identified as having left ventricular enlargement with each regression model compared to previously published reference limits or guidelines. We then identified breeds failing to conform to generic dog models. RESULTS: The American College of Veterinary Internal Medicine-recommended scaling exponent (0.294) and criterion for identifying left ventricular enlargement (1.7) identified >10% of apparently healthy dogs as having left ventricular enlargement, with specific breeds being misclassified up to 50% of the time. However, with a scaling exponent of 0.33, a constant of 1.7 represented a normal left ventricular size in 97.5% of healthy dogs in both generic and non-conforming breeds. CONCLUSIONS: Left ventricular internal dimension in diastole normalized to bodyweight is breed-dependent. A constant of 1.7 with a scaling exponent of 0.294 does not always represent ventricular enlargement; a scaling exponent of 0.33, with breed-specific reference limits for breeds that fail to conform to allometric models of generic dogs, reduces the misclassification of healthy dogs as having left ventricular enlargement.

Transvenous detachable coiling of patent ductus arteriosus in small dogs.

OBJECTIVE: To report on transvenous detachable coiling in small dogs deemed ineligible for traditional transarterial patent ductus arteriosus occlusion and compare transthoracic echocardiographic and angiographic measurements to determine their equivalence. MATERIALS AND METHODS: A retrospective study of 35 dogs that underwent transvenous coiling of a patent ductus arteriosus. Demographic information, echocardiographic and angiographic studies, surgery reports, and follow-up evaluation of residual flow were obtained. A Bland-Altman analysis was used to compare echocardiographic and angiographic measurements of the minimal ductal diameter (Echo-MDD, Ang-MDD) and ampulla diameter (Echo-A, Ang-A). RESULTS: Thirty-four of 35 dogs had successful deployment of a coil, with one dog undergoing occlusion with a different device after the exteriorized coil pulled through the ductus. Complete occlusion was achieved in 18 dogs within 24 h; four dogs were lost to follow-up, and the remaining 12 dogs had no residual flow or a significant reduction in shunting with normalization in cardiac chamber dimensions by a median of 99 days. Thirty percent of dogs (11/35) experienced perioperative complications of which 10 were minor complications. The analysis of 26 dogs with both echocardiographic and angiographic ductal measurements showed a -0.14 mm mean difference (95% limits of agreement -1.08 to 0.8 mm) in minimal ductal diameter and -0.68 mm mean difference (95% limits of agreement -2.73 to 1.37 mm) in ampulla diameter. CONCLUSIONS: Dogs less than 3 kg deemed too small for transarterial occlusion can successfully undergo transvenous coil embolization of patent ductus arteriosus.

Transthoracic echo-guided pacemaker implantation reduces fluoroscopic use in dogs.

Echocardiographic guidance provides an alternative method when fluoroscopy is unavailable, equipment or power failure of fluoroscopic equipment during a procedure occurs or to decrease radiation risk. Recently, transthoracic (TTE) and transesophageal echocardiography were reported as an alternative method to guide interventional procedures in dogs. Therefore, we hypothesized that TTE could be used as an alternative method to visualize endocardial leads during pacemaker implantation in dogs, largely avoiding the use of fluoroscopy. A prospective consecutive case series of pacemaker implantation was performed using TTE guidance. The endocardial lead was imaged by TTE during its intracardiac advancement until the lead tip was positioned at the right ventricular apex. Echocardiographic right parasternal views, optimized to visualize the pacing lead, were used, starting with a short axis image of the right atrium and ending with a long axis view of the right ventricle (RV) optimized to image the RV apex. Proper lead placement was confirmed by both capture threshold, impedance and fluoroscopy. Twenty-one pacemaker implantation procedures by TTE monitoring were successfully performed. The TTE guidance provided images of a quality sufficient to clearly monitor implantation in real-time and allowed for immediate corrections to pacing lead malpositioning or excessive looping. Fluoroscopy was used to confirm the correct placement of the lead that was guided echocardiographically in the initial three procedures, after which a single radiographic image (no cine-mode) was used to identify lead placement and redundancy in the remaining eighteen cases. Static imaging (radiography using the fluoroscope) was used to assess the proper lead redundancy in all procedures because this cannot be evaluated echocardiographically. Pacemaker leads were successfully implanted in the RV of dogs using TTE monitoring. A larger cases series is needed for validation of safety and effectiveness of TTE during this interventional procedure in dogs.

The effects of activity, body weight, sex and age on echocardiographic values in English setter dogs.

BACKGROUND: Breed-specific reference intervals improve echocardiographic interpretation and thereby reduce misdiagnoses, especially in athletic breeds. OBJECTIVES: The objectives of the study were to examine transthoracic echocardiographic values in healthy adult English setter dogs and determine the effects of activity, body weight, sex and age on these values. ANIMALS, MATERIALS AND METHODS: One hundred and one adult English setter dogs, recruited from local veterinary clinics and from the Norwegian English setter club, underwent routine transthoracic echocardiography. The population was stratified into two groups based on the reported level of activity. The effects of activity level, body weight, sex and age on echocardiographic variables were examined. Results were compared with published data from other breeds and from a pre-existing species-wide allometric model. RESULTS: Of the 100 dogs between 19 months and 10 years of age included in the study, 72 were reported as very active and 28 as less active. Echocardiographic intervals were calculated for body size-independent echocardiographic variables. The upper limits of the intervals for left-atrial-to-aortic ratios and normalised left ventricular volumes exceeded those of various, previously published studies of other breeds. Normalised left ventricular dimensions exceeded published allometric 95th percentile upper reference values in 13% of dogs in diastole and 32% of dogs in systole. More active dogs had larger cardiac dimensions than less active dogs; however, the activity level did not predict echocardiographic variables when included in a multiple regression model. CONCLUSIONS: The study provides breed specific transthoracic echocardiographic values for English setter dogs, thereby contributing to improve diagnostic assessment of cardiac health in this breed.

Utility of thoracic ultrasonography in a rapid diagnosis of angiostrongylosis in young dogs presenting with respiratory distress.

The nematode, Angiostrongylus vasorum is a nematode that lives in the pulmonary arteries of canids and has an obligate gastropod intermediate host. It can cause various clinical signs. with the two most common clinical scenarios consisting of acute respiratory distress and haemorrhagic diathesis, either separately or together. Younger dogs (< 2 years) are overrepresented, and dogs often show pulmonary granulomata (radiographically and pathologically). Thoracic ultrasonography offers a safe, rapid, commonly available, non-invasive means of assessing the lungs. We prospectively examined the utility of thoracic ultrasonography in the diagnosis of angiostrongylosis in 26 client-owned dogs <2 years old, presenting with respiratory distress. We identified small hypoechoic subpleural nodules in 15/26 dogs; 14 of these were subsequently confirmed to have angiostrongylosis by faecal Baermann concentration test, A. vasorum antigen testing or both. The remaining 11 dogs without subpleural nodules had negative faecal analysis and A. vasorum antigen testing and diagnosed with other respiratory diseases. This resulted in a sensitivity of 100% and a specificity of 92% for the detection of angiostrongylosis by thoracic ultrasonography in young dogs presenting with respiratory distress. Our results suggest that thoracic ultrasonography might offer a safe, rapid, relatively accurate diagnostic test for diagnosis of angiostrongylosis in young adult dogs with respiratory distress living in endemic areas.

Two-dimensional echocardiographic measures of left ventricular dimensions agree with M-mode measurements in dogs.

INTRODUCTION: Clinicians measure left ventricular dimensions in dogs from both M-mode and two-dimensional images. Little information currently exists as to whether these two methods provide measurements similar enough to be interchangeable. ANIMALS: The animals included in this study are 206 client-owned dogs: 68 healthy, 105 with myxomatous mitral valve disease, 33 with other cardiac or extracardiac disease. MATERIALS AND METHODS: Investigators measured left ventricular diastolic and systolic dimensions from archived M-mode and two-dimensional images obtained from the right parasternal short-axis view. Agreement between the pairs of measurements was examined using limits of agreement (Bland-Altman) plots. RESULTS: Left ventricular diastolic dimensions showed no fixed or proportional bias but did show heteroscedasticity. Ninety-five percent limits of agreement for normalized differences approximated ±10%; 95% of the absolute differences for any pair of measurements were <3.9 mm regardless of bodyweight and <2.7 mm for dogs <15 kg. Left ventricular systolic dimensions showed slight proportional bias, with two-dimensional measurements being progressively larger than M-mode measurements as ventricular size increased. Ninety-five percent limits of agreement for normalized differences approximated ±20%; 95% of the absolute differences for any pair of measurements were <4.6 mm regardless of bodyweight and <3.5 mm for dogs <15 kg. Mitral valve disease did not appreciably affect these findings. CONCLUSIONS: Left ventricular internal dimensions in dogs with and without cardiac disease measured from two-dimensional right parasternal short-axis images are interchangeable with those measured from M-mode images using the same view.

Two-dimensional echocardiographic estimates of left ventricular volumes obtained in different views in dogs provide similar measurements but are not interchangeable.

INTRODUCTION: Little information exists regarding the interchangeability of left ventricular volume estimates using a monoplane Simpson's Method of Discs on images obtained from the left apical four-chamber and right parasternal long axis four-chamber views. We examined if volume estimates obtained from these views were interchangeable. ANIMALS: A total of 224 dogs: 86 healthy, 96 with mitral valve disease, 42 with various cardiac pathologies. MATERIALS AND METHODS: Investigators obtained right parasternal long-axis and left apical four-chamber views from each dog and used manufacturer-supplied software to estimate left ventricular volumes in diastole and systole using Simpson's Method of Discs. Estimates based on linear measurements (diameter cubed, 0.67∗diameter cubed, and Teichholz) were also calculated. Reproducibility for each view, and agreement between the estimates obtained with each view, and those calculated from linear dimensions, were examined using Limits of Agreement. Reference intervals for volumes indexed to bodyweight and body surface area were calculated. RESULTS: Neither method proved very reproducible. Although no bias was detected, the agreement between volumes indexed to bodyweight and body surface area was insufficient to recommend interchangeability. Estimates based on Teichholz and diameter cubed methods overestimated volumes; however, those based on 0.67∗diameter cubed performed reasonably. CONCLUSIONS: Monoplane volume estimates from the left apical and right parasternal long axis four-chamber views are similar but not interchangeable. Clinicians can perform crude estimates of left ventricular volume using the equation 0.67∗diameter cubed.

The use of thermometer protective sheets provides reliable measurement of rectal temperature: a prospective study in 500 dogs.

OBJECTIVES: To measure and compare rectal temperature measurement with and without thermometer protective sheaths. To survey veterinary practices regarding thermometer use and disinfection. MATERIALS AND METHODS: Thermometers were validated with and without protective sheaths for accuracy and repeatability in a water bath with a high precision thermometer as reference. Then, the rectal temperature of 500 dogs was measured with and without protective sheaths in randomised order. The difference in temperature measured by the two methods was analysed with a generalised linear model with order of temperature measurement, life stage, dog size, body condition, level of consciousness, class of temperature and operator as explanatory variables. Practical thermometer use and disinfection was surveyed by online questionnaire. RESULTS: In the pre-clinical phase, study thermometers recorded average temperature differences of −0.05 ± 0.07°C (mean ± SD) and −0.03 ± 0.08°C with and without sheath, respectively and the coefficients of variation ranged from 0.1 to 0.5% with and without sheath. In the clinical study, temperatures measured with and without sheaths differed by less than ±0.2°C for 92% of the measurements. None of the explanatory variables were associated with the observed differences. Twenty-five percent of survey respondents were aware of the guidelines for disinfection of thermometers. CLINICAL SIGNIFICANCE: Thermometer protective sheaths do not affect the measurement of canine rectal temperature in the clinic.

Pulmonary vein to pulmonary artery ratio in healthy and cardiomyopathic cats.

INTRODUCTION/OBJECTIVES: Recognition of congestive heart failure (CHF) in dyspnoeic cats is crucial for correct intervention. The pulmonary vein (PV) to pulmonary artery (PA) ratio (PV/PA) has been proposed as an index that might help discriminate dogs suffering from CHF but has never been studied in cats. We sought to determine reference intervals for various PV and PA variables in healthy cats. We then examined these variables in cats with subclinical and clinical cardiomyopathies to determine their diagnostic utility in identifying CHF. ANIMALS, MATERIALS AND METHODS: We took a sample of 114 cats: 51 healthy cats, 32 subclinical cardiomyopathy affected cats and 31 cardiomyopathic cats with CHF. PV and PA were measured at the minimal and maximal diameters using M-mode images obtained from a modified right parasternal long axis view. The aorta (Ao) and left atrium were measured using two-dimensional imaging employing the right parasternal short axis view. RESULTS: median PVmin/PAmin value in healthy cats was approximately 0.51 and the PVmax/PAmax value was 0.67. The median distensibility value of the vessels was 23% for ΔPA and 41% for ΔPV. Cats with CHF had higher PVmin/PAmin, PVmax/PAmax, PVmin/Ao, PVmax/Ao values and a smaller ΔPV value compared to subclinical and healthy cats (p < 0.0001). When evaluating the diagnostic performance of these variables (in cardiomyopathic cats), PVmin/PAmin and PVmin/Ao values had higher accuracy compared to the LA:Ao value when identifying cats with CHF. CONCLUSIONS: Our study provides reference values for PV and PA variables in cats. Moreover, PV/PA variables were better factors than LA:Ao for discriminating cardiomyopathic cats with and without CHF.

Short-term biological variation of serum thyroid hormones concentrations in clinically healthy cats.

Thyroid disease is common in cats, but little is known about the biologic variability of serum thyroid hormone concentrations and its impact on diagnostic utility in either healthy cats or cats with thyroid disease. The purpose of this study was to determine the biological variation, index of individuality, and reference change values for thyroid hormones and thyroid-stimulating hormone (TSH) in clinically healthy cats. Serum samples for analysis of total thyroxine (T4), triiodothyronine (T3), free T4 by dialysis, and TSH were obtained weekly for 6 wk from 10 healthy cats, then frozen until single-batch analyzed. Data were evaluated for outliers, and we determined the CV within individual cats (CVI) and between individual cats (CVG) for each hormone and the variation between duplicates or analytical variation (CVA). The index of individuality and reference change values for each hormone were then calculated. Serum concentrations of total T4, free T4, T3, and TSH all showed greater variation between cats (CVG) than within cats (CVI). Total and free T4 had an intermediate index of individuality (1.1 and 1.2, respectively), suggesting that these hormones would be best evaluated by a combination of their population-based reference intervals and reference change values. Serum TSH concentrations had high index of individuality (1.8), suggesting this hormone would be best evaluated with reference change values rather than the population-based reference interval. Total T3 also had a high calculated index of individuality (1.8); however, T3 had high ratio of analytical variation (CVA) to within cat variation (CVI), so RCV could not be accurately calculated. This study demonstrates that clinically normal cats show considerable interindividual biological variation in serum thyroid hormone and TSH concentrations, whereas the intraindividual variability in hormone concentrations is much narrower. This suggests that for all serum thyroid hormones, but especially serum TSH and T3 concentrations, comparing individual cat's hormone results to a population-based reference interval may be misleading, especially in those with early or subclinical thyroid disease. Clinicians might improve the diagnosis of feline thyroid disease by establishing baseline concentrations of T4, free T4, T3, and TSH for individual cats (ideally when healthy) and applying reference change values to subsequent measurements.

Two-dimensional echocardiographic left- atrial-to-aortic ratio in healthy adult dogs: a reexamination of reference intervals.

INTRODUCTION: Left atrial-to-aortic ratios (LA:Ao) provide a body weight independent estimate of left atrial size. However, reference intervals were established with small sample populations and for only single points in the cardiac cycle. More robust reference intervals are warranted. ANIMALS: Two hundred and thirty eight apparently healthy adult dogs. MATERIALS AND METHODS: LA:Ao measurements were obtained at 3 points in the cardiac cycle - maximal dimension, at the closing of the aortic valve (or just before opening of the mitral valve) (LA:AoMAX); minimal dimension, at the onset of the QRS complex (LA:AoMIN) and at the onset of atrial systole (LA:AoP). LA:AoMAX was obtained from right parasternal short and long-axis views, and LA:AoMIN and LA:AoP were obtained from the right parasternal short-axis view. Dogs were excluded from analyses of reference intervals if weight-based left atrial and left ventricular diastolic dimensions exceeded reference interval limits. Effects of breed and body weight on LA:Ao measurements were examined. RESULTS: Upper LA:Ao reference limits mostly agreed with previously published limits, although 10% of dogs had LA:AoMAX in the short-axis view exceeding 1.6. These dogs had smaller aortae than expected for their body weight, and included mostly boxers and English setters. Reference limits for LA:AoMIN and LA:AoP were smaller than those for LA:AoMAX in either view. No LA:Ao measurements were associated with body weight. CONCLUSIONS: Reference limits were either confirmed or established for the common two-dimensional methods of assessing relative left atrial size in healthy dogs. Clinicians should use caution when diagnosing mild left atrial enlargement in certain dog breeds and should examine the weight-based aortic dimensions in such cases.

Breed does not affect the association between murmur intensity and disease severity in dogs with pulmonic or subaortic stenosis.

OBJECTIVES: To determine whether breed affects the ability of murmur intensity to predict the severity of stenosis in dogs with pulmonic stenosis or subaortic stenosis. MATERIALS AND METHODS: Retrospective multi-investigator study of dogs with pulmonic stenosis or subaortic stenosis. Murmur intensity, assessed by a four-level classification scheme, was compared with echocardiographically-determined pressure gradient across the affected valve. Breeds represented by at least 10 dogs at any murmur intensity were compared to determine the effect, if any, of breed. RESULTS: A total of 1088 dogs (520 with pulmonic stenosis and 568 with subaortic stenosis, representing 106 breeds and the mixed breed group) were included; 208 dogs had soft, 210 had moderate, 283 had loud and 387 had palpable murmurs. Fifteen breeds were represented by at least 10 dogs: five breeds with at least 10 dogs had soft murmurs (132 dogs), nine breeds had moderate murmurs (149 dogs), 10 breeds had loud murmurs (188 dogs), and 11 breeds had palpable murmurs (286 dogs). No breeds differed in stenosis severity from any other breeds within any murmur grade. Post hoc power calculations suggested that we would have been able to detect at least a moderate or large effect size, had one existed. Several dogs with soft murmurs had more-than-mild disease severity. CLINICAL SIGNIFICANCE: Despite anecdotally perceived differences in the detection of heart murmurs between breeds, which have been proposed to potentially affect the interpretation of stenosis severity, we found no obvious breed effect in the ability to predict severity of stenosis.

Right ventricular outflow tract fractional shortening: an echocardiographic index of right ventricular systolic function in dogs with pulmonary hypertension.

OBJECTIVES: To create reference intervals for right ventricular outflow tract fractional shortening (RVOT-FS) in healthy dogs and examine diagnostic performance of this index in dogs with pulmonary hypertension (PH). In addition, we examine the impact of myxomatous mitral valve disease (MMVD) without PH on RVOT-FS. ANIMALS, MATERIALS AND METHODS: The study population included 52 healthy adult dogs, 51 dogs with MMVD but without PH, and 51 dogs with PH. This is a prospective study. Complete echocardiographic evaluations were performed on all dogs. Right ventricular outflow tract fractional shortening was obtained by two-dimensional guided M-mode recordings from the right parasternal short axis view. Right ventricular outflow tract fractional shortening was evaluated in healthy dogs of various breeds, and reference intervals were generated. We examined the effect of PH on RVOT-FS with receiver operating characteristic analysis and evaluated the effect of MMVD on RVOT-FS in dogs without PH. Intraobserver and interobserver reproducibility was calculated. RESULTS: Healthy dogs had RVOT-FS > 44%. Right ventricular outflow tract fractional shortening values of healthy dogs and MMVD dogs without PH did not differ (p=0.84). In dogs with PH, RVOT-FS decreased with increasing tricuspid regurgitation velocity (p<0.0001). Pimobendan use in dogs with PH increased RVOT-FS as PH worsened. Right ventricular outflow tract fractional shortening was acquired with clinically acceptable intraobserver and interobserver reproducibility. CONCLUSIONS: Right ventricular outflow tract fractional shortening is a novel, easy applicable, and repeatable index for evaluating RV systolic function. Studies comparing this index with common echocardiographic indices used to assess RV function in dogs are needed.