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.

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.

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.

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.

Mini-invasive approach for removal of iliopsoas migrating grass awns with an atraumatic wound retractor.

This case series describes a novel mini coeliotomy approach using a radial, atraumatic self-retaining retractor for the retrieval of migrant plant foreign bodies from the iliopsoas muscles of six male dogs under intra-operative ultrasonographic guidance. Four dogs had a history of pulmonary disease potentially compatible with inhalation of a foreign body approximately 2-4 months before presentation. Under ultrasonographic guidance, the grass awns were identified in the iliopsoas muscle and were completely removed. In this case series, the annular ring device provided an excellent view of the surgical field for intra-abdominal manipulations. Patient follow-up at 15 days and 6 to 12 months after surgery indicated a full recovery, and no grass awn fragment residues were identified.

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.

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.

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.

Low-energy ablation of anteroseptal accessory pathways in two dogs.

In humans, accessory pathways (APs) in an anteroseptal and midseptal position are often challenging to ablate because of their close proximity with the conduction pathways of the atrioventricular junction. The use of low-energy ablation techniques can be useful to reduce the risk of permanently damaging the atrioventricular node and the His bundle. This report describes the use of low-energy radiofrequency catheter ablation to successfully and permanently ablate anteroseptal APs in two dogs with orthodromic atrioventricular reciprocating tachycardia. In the first dog, a transient first degree atrioventricular block persisted for 30 s after radiofrequency energy delivery. In the second dog, transient paroxysmal atrioventricular conduction block was observed during the procedure but resolved within 3 days. First degree atrioventricular block was again identified 2 months later. In conclusion, anteroseptal APs can be effectively treated by low-energy radiofrequency catheter ablation with minimal and transient damage to the atrioventricular junction.

Tricuspid annular plane systolic excursion-to-aortic ratio provides a bodyweight-independent measure of right ventricular systolic function in dogs.

OBJECTIVES: To evaluate whether tricuspid annular plane systolic excursion (TAPSE) can be normalized to aortic valve (Ao) measurements in dogs. To determine TAPSE:Ao reference intervals for healthy dogs and examine diagnostic performance of TAPSE:Ao in dogs with pulmonary hypertension (PH). ANIMALS: One hundred and thirty-seven healthy adult dogs; 115 dogs with myxomatous mitral valve disease (MMVD) but no PH; 91 dogs with PH. METHODS: A combined prospective and retrospective study. Full echocardiographic evaluations were performed on all dogs; TAPSE was indexed to Ao to produce a unitless TAPSE:Ao. Reference intervals for TAPSE:Ao were generated, and TAPSE:Ao was regressed on tricuspid regurgitant jet velocity in dogs with PH and on LA:Ao in dogs with MMVD without PH. Diagnostic test analysis was used to examine the ability of TAPSE:Ao to identify severe PH. An adjusted TAPSE:Ao (TAPSE:Ao(adj)) was derived to account for MMVD in dogs with PH. RESULTS: The ratio, TAPSE:Ao, removed the effect of bodyweight from TAPSE measurements. Healthy dogs had TAPSE:Ao > 0.65. The ratio, TAPSE:Ao, showed a linear negative relationship with tricuspid regurgitation velocity and positive relationship with LA:Ao. The adjusted ratio, TAPSE:Ao(adj), increased the sensitivity of diagnosis of PH in dogs with moderate-severe MMVD without affecting the diagnosis of PH in dogs with PH and with no or mild MMVD. CONCLUSIONS: The ratios, TAPSE:Ao and TAPSE:Ao(adj), are a bodyweight-independent means of assessing right ventricular systolic function in dogs and for identifying severe PH in dogs with or without MMVD.

Left atrial deformation and phasic function determined by two-dimensional speckle-tracking echocardiography in dogs with myxomatous mitral valve disease.

INTRODUCTION: Left atrial (LA) function can provide useful information in dogs with myxomatous mitral valve disease (MMVD). Recently, we have demonstrated the feasibility of measuring LA longitudinal deformation using speckle-tracking echocardiography (STE) to estimate LA function in healthy dogs. Whether LA strain and strain rate variables provide additional information about LA function and clinical cardiac status in dogs with MMVD remains unexplored. ANIMALS: Ninety-six client-owned dogs of different breeds with MMVD were prospectively enrolled. METHODS: LA longitudinal deformation was evaluated in each dog by STE and different STE variables were used to assess LA function. RESULTS: No STE variables differed between American College of Veterinary Internal Medicine Stage B1 and B2 dogs but were lower in Stage C dogs. Peak atrial longitudinal average strain < 27.9%, left-atrial-to-aortic ratio > 2.2 and peak atrial contraction average strain < 7.25% discriminated symptomatic MMVD dogs by receiver operating characteristic analysis with sensitivity and specificity of 100% and 100% (95% confidence interval [CI] 91-100%), 92% (95% CI 78-98%) and 98% (95% CI 87-100%), 100% (95% CI 91-100%) and 95% (95% CI 83-99%), respectively. In 12 dogs with similar left-atrial-to-aortic ratio, peak atrial longitudinal average strain and peak atrial contraction average strain differentiated dogs with subclinical disease from those with congestive heart failure (CHF). CONCLUSION: Dogs with MMVD in CHF appear to have lower LA longitudinal strain and strain rate variables compared with dogs with subclinical disease. Further studies are needed to establish if our initial findings can provide useful information for the diagnosis, treatment, and prognosis of dogs with MMVD.

Murmur intensity in adult dogs with pulmonic and subaortic stenosis reflects disease severity.

OBJECTIVES: The aims of this study were to determine whether murmur intensity in adult dogs with pulmonic stenosis or subaortic stenosis reflects echocardiographic disease severity and to determine whether a six-level murmur grading scheme provides clinical advantages over a four-level scheme. MATERIALS AND METHODS: In this retrospective multi-investigator study on adult dogs with pulmonic stenosis or subaortic stenosis, murmur intensity was compared to echocardiographically determined pressure gradient across the affected valve. Disease severity, based on pressure gradients, was assessed between sequential murmur grades to identify redundancy in classification. A simplified four-level murmur intensity classification scheme ('soft', 'moderate', 'loud', 'palpable') was evaluated. RESULTS: In total, 284 dogs (153 with pulmonic stenosis, 131 with subaortic stenosis) were included; 55 dogs had soft, 59 had moderate, 72 had loud and 98 had palpable murmurs. 95 dogs had mild stenosis, 46 had moderate stenosis, and 143 had severe stenosis. No dogs with soft murmurs of either pulmonic or subaortic stenosis had transvalvular pressure gradients greater than 50 mmHg. Dogs with loud or palpable murmurs mostly, but not always, had severe stenosis. Stenosis severity increased with increasing murmur intensity. The traditional six-level murmur grading scheme provided no additional clinical information than the four-level descriptive murmur grading scheme. CLINICAL SIGNIFICANCE: A simplified descriptive four-level murmur grading scheme differentiated stenosis severity without loss of clinical information, compared to the traditional six-level scheme. Soft murmurs in dogs with pulmonic or subaortic stenosis are strongly indicative of mild lesions. Loud or palpable murmurs are strongly suggestive of severe stenosis.

Canine pulmonary vein-to-pulmonary artery ratio: echocardiographic technique and reference intervals.

OBJECTIVES: The size of the pulmonary veins (PVs) and pulmonary arteries (PAs) changes in response to hemodynamic alterations caused by physiological events and disease. We sought to create standardized echocardiographic methods for imaging the right ostium of the pulmonary veins (RPVs) and the right pulmonary artery (RPA) using specific landmarks and timing to quantify vessel diameters and phasic changes during the cardiac cycle. ANIMALS: Fifty client-owned healthy dogs prospectively recruited. METHODS: M-mode and 2-dimensional images were obtained from modified right parasternal long and short axis views. Right ostium of the pulmonary veins and RPA measurements were timed with electrical [peak of the QRS complex (RPVQRS and RPAQRS) and end of T wave (RPVT and RPAT)] or mechanical events [RPV and RPA vessels at their respective maximal (RPVMAX; RPAMAX) and minimal (RPVMIN; RPAMIN) diameters]. Right ostium of the pulmonary veins and RPA measurements were also indexed to the aorta. RESULTS: In normal dogs regardless of the echocardiographic view or time in the cardiac cycle, the RPV/RPA ratio approximated 1.0. Mechanically timed fractional changes (distensibility indices) in RPV and RPA diameters did not differ (p=0.99; 36.9% and 36.8%, respectively). ECG-timed fractional changes (distensibility indices) in RPV and RPA diameter were at least 50% smaller than mechanically timed changes (p<0.05). RPV:Ao and RPA:Ao ranged between 0.3 and 0.6, with lower values obtained in diastole and larger values in systole (p<0.0001). Multiple positive and negative deflections were identified on the RPV and RPA M-mode tracings. CONCLUSION: This study provides detailed methodology and 2D and M-mode reference intervals for the RPV and RPA dimensions and the phasic changes during the cardiac cycle of the dog using echocardiography.

Transthoracic ultrasound guided balloon dilation of cor triatriatum dexter in 2 Rottweiler puppies.

Balloon dilation was performed in two Rottweiler puppies with cor triatriatum dexter and clinical signs of ascites using transthoracic echocardiographic guidance. The dogs were positioned on a standard echocardiography table in right lateral recumbency, and guide wires and balloon catheters were imaged by echocardiographic views optimized to allow visualization of the defect. The procedures were performed successfully without complications and clinical signs were resolved completely in both cases. Guide wires and balloon catheters appeared hyperechoic on transthoracic echocardiography image and could be clearly monitored and guided in real-time. These two cases demonstrate that it is possible to perform balloon catheter dilation of cor triatriatum dexter under transthoracic guidance alone.

Left atrial deformation and phasic function determined by 2-dimensional speckle tracking echocardiography in healthy dogs.

INTRODUCTION: Feasibility, intra- and inter-observer variability of measuring left atrial (LA) longitudinal strain and strain rate (SR) variables using speckle tracking echocardiography (STE) have not been reported in the dog. Reference intervals for these variables which can be useful to estimate LA function have been provided. ANIMALS: Forty-eight healthy adult dogs. MATERIALS AND METHODS: Left atrial longitudinal deformation was evaluated in each dog by STE, and different combinations of STE variables were used to describe the 3 phases (reservoir, conduit and booster pump phase) of the LA function. RESULTS: Left atrial STE was possible in 40/48 dogs (83%). Strain and SR curves in healthy dogs were characterized, and reference intervals for several strain and SR variables are provided. Intra- and inter-observer variability, expressed as percent difference between observations or observers, was 3.58%-10.8% for indices of the LA reservoir function, 10.48%-15.82% for indices of the LA conduit function and 14.1%-34% for indices of the LA contractile function. Strain rate in early diastole and strain rate at atrial contraction variables were correlated significantly with age. No other relationships (body weight, heart rate or LA size) with any STE variables could be identified. CONCLUSION: Speckle tracking echocardiography provides quantitative measurements of LA longitudinal deformation and can be used to assess LA phasic function in healthy dogs. Further studies of these variables in dogs with cardiac diseases are needed to determine the clinical applicability and utility.

The times they are a-changin': Two-dimensional aortic valve measurements differ throughout diastole.

INTRODUCTION: Diastolic aortic valve measurements are used to obtain weight-independent cardiac ratiometric indices. However, whether clinically important variations in valve measurements occur during diastole remains undetermined. ANIMALS: One hundred sixty-three dogs and 40 cats; a mixture of healthy animals and patients with heart disease. MATERIALS AND METHODS: Aortic valve diameter and area were measured at three time-points: early diastole {AoMAX}, during the P-wave {AoP} and at end-diastole {AoMIN}. Measurement beat-to-beat variability was determined. Difference plots were generated for each measurement pair. Aortic measurements were compared by repeated measures analysis of variance. RESULTS: In dogs, normalised aortic diameters showed a fixed bias of approximately 14% for AoMAX-AoMIN, 6% for AoMAX-AoP and 8% for AoP-AoMIN. In cats, the aortic diameter and area biases were all less than 2.5% and less than 7% respectively. AoMAX was the largest measurement in 78% patients and AoMIN was the smallest measurement in 73% patients. In dogs, AoMAX > AoP > AoMIN (p < 0.0001). Median within-patient measurement variability was 5% for linear dimensions and 8% for area measurements in dogs and 4.5% for linear and 10.4% for area in cats. DISCUSSION: Aortic measurements in dogs differ significantly throughout diastole, with Ao(A)MAX > Ao(A)P > Ao(A)MIN. These differences could clinically impact cardiac ratiometric indices. The difference in cats is less than the within-patient measurement variability and unlikely to be of clinical significance. CONCLUSIONS: Operators should adopt a single diastolic time-point for measurement of the aorta to ensure consistency in measuring and reporting in echocardiography.

Acute undifferentiated leukaemia in a dog.

BACKGROUND: Acute undifferentiated leukaemia (AUL) is considered a separate entity in the context of acute leukaemias. AUL is extremely rare in both humans and dogs, has a rapid clinical course and does not respond to treatment. It is characterised by the presence of blast cells within the bone marrow and/or peripheral blood at levels ≥ 20% and even up to 100% of all nucleated cells. Blast cells are unable to be differentiated on morphological, cytochemical and phenotypic criteria into myeloid or lymphoid lineages because of their immaturity and/or atypia. CASE REPORT: An 8-year-old German Shepherd dog was referred for depression, asthenia, mild anaemia, thrombocytopenia and marked leucocytosis. Abdominal ultrasound showed hepatomegaly, splenomegaly, bilateral nephromegaly and enlargement of mesenteric lymph nodes. Echocardiography revealed biventricular hypertrophy with abnormal tissue density of the myocardium. Blood and bone marrow smears were composed of 95% unclassifiable and/or atypical blast cells and signs of dysplasia of the erythroid and thrombocytic/megakaryocytic lineages were present. Blast cells were negative for all cytochemical stains used and flow cytometry of peripheral blood revealed 85% of total leucocytes consisting of small-to-medium-sized cells, negative for all lymphoid and myeloid markers except CD45 and CD34. After necropsy, cytology and histology revealed that blast cells had diffusely infiltrated all tissues examined. Both erythroid and megakaryocytic extramedullary haemopoiesis was also detected in the spleen, lymph nodes and liver. All immunohistochemical stains used were negative. CONCLUSION: On the basis of all the results, a diagnosis of acute leukaemia involving a very primitive haematopoietic precursor was made.