Echocardiographic reference intervals for volumetric measurements of the left ventricle using the Simpson's method of discs in 1331 dogs

Cardiac biomarkers N-terminal fragment of the prohormone B-type natriuretic peptide and cardiac troponin I for characterization of the cardiac disease phenotype of the English Bull Terrier

The N-terminal fragment of prohormone B-type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) contribute information regarding cardiac load and function and myocardial injury, respectively, to the clinical work-up of dogs with heart disease. The English bull terrier (BT) has a predisposition to a complex cardiac phenotype. This prospective case-control study aimed to further characterize this phenotype through cardiac biomarker evaluation. Fifteen healthy BT (group 1) and 50 BT with various heart disease presentations (groups 2-4) were included. The main presentations were MVD (45 dogs) and MS (13 dogs). 16/50 dogs had echocardiographic evidence of cardiac remodeling: 7 with either increased left atrial (LA) or left ventricular (LV) volumes (group 3) and 9 with increased LA and LV volumes (group 4). Cardiac biomarkers were not significantly different between dogs with disease subtypes MVD or MS versus dogs with other disease presentations. When evaluated in relation to remodeling, median NT-proBNP and cTnI in group 4 (1004 pmol/L, 0.09 ng/mL) were significantly higher than in group 1 (257 pmol/L, 0.02 ng/mL), group 2 (300 pmol/L, 0.026 ng/mL) and group 3 (250 pmol/L, 0.02 ng/mL). There was significant discriminatory ability for both biomarkers between group 4 and groups 1, 2 or 3. Furthermore, cTnI significantly differentiated dogs with any degree of remodeling (groups 3 + 4) from those without (groups 1 + 2). The cardiac disease phenotype of the BT is not associated with a unique cardiac biomarker profile. Rather, biomarker levels are similar to those reported in other breeds with valvular heart disease.

Echocardiographic classification of dogs with aortic stenosis: potential utility of a novel staging system

INTRODUCTION

Severity of aortic stenosis (AS) in humans is classified using a staging system based on two-dimensional echocardiographic changes, which considers the extent of global cardiac damage. Currently, classification of canine AS is based on trans-aortic pressure gradient (PG) alone. This study aimed to retrospectively classify dogs with AS based on an adapted human staging system, exploring feasibility of classification and the association between stage and features such as PG and clinical signs.

ANIMALS

This study included 87 client-owned dogs.

MATERIALS AND METHODS

Clinical and echocardiographic data were retrieved from computerised records. Dogs were classified according to a modified human staging system (Stages: 0/1/2+). Descriptive statistics were explored. Differences in signalment, PG, and clinical signs between stages were evaluated using appropriate statistical tests. Significance was identified if P<0.05 after correction for multiple comparisons.

RESULTS

Forty-one dogs were classified as Stage 0, 36 as Stage 1, and 10 as Stage 2+. No difference in signalment or weight was identified between stages. Dogs classified as Stage 2+ were more likely to have clinical signs than those in Stages 0 or 1 (50% vs. 7% [P=0.004] and 17% [P=0.043], respectively) and had a higher PG than dogs in Stage 0 (90 mmHg [35-143 mmHg] vs. 25 mmHg [18-182 mmHg], P=0.001).

CONCLUSIONS

This study presents an alternative way to classify dogs with AS. Data support further study of the staging system to compare whether or not this classification has additional value over assessment of PG alone.

Transthoracic echocardiographic reference intervals in 214 adult Golden retrievers

This study describes the echocardiographic reference intervals in a large sample of Golden retrievers from the database of the Italian Veterinary Observatory for Cardiac Diseases. The echocardiographic variables and the cardiac functionality indexes obtained from 2012 to 2022 in 214 (122 females, 92 males) healthy adult Golden retrievers were compared with the previously published data for this breed and with data from the general canine population and other breeds. The diastolic left ventricular internal diameter and the left ventricle's systolic and diastolic allometric indices were higher than those reported for the general canine population (P<0.05). The same was true for the left ventricular end-diastolic and end-systolic volumes measured by Simpson's method of discs (P<0.01). Fractional shortening of the left ventricle was lower (P=0.002) and aortic flow velocity was higher (P<0.001) than the value previously reported for Golden retrievers. The reference intervals obtained in this study are useful for clinical echocardiography and for echocardiographic screening programs in Golden retrievers.

Dogs fed a high protein, low carbohydrate diet have elevated postprandial plasma glucagon and amino acid concentrations and tend to have lower glucose concentrations compared to two different moderate protein, moderate carbohydrate diets

As dog owners continue to seek to feed their dogs similarly to themselves, there is demand for high protein, low carbohydrate (HPLC) diets. The consumption of HPLC diets can improve glycemic control, similarly to high fiber diets. However, the effects of HPLC and high fiber diets on cardiac function have yet to be evaluated in healthy dogs. The objective of the present study was to investigate the glucose, insulin, glucagon and amino acid (AA) postprandial response and echocardiographic measurements in laboratory-housed, adult large breed dogs fed a commercially available HPLC, a moderate protein, moderate carbohydrate (MPMC), or a commercially available MPMC, high fiber, "metabolic" diet for 42 d. This study was conducted as a 3 × 3 Latin square where dogs received: 1) a commercial HPLC diet (48% of metabolizable energy (ME) from protein, 10% of ME from nitrogen-free extract; NFE), 2) a MPMC diet (28% of ME from protein, 39% of ME from NFE) formulated with the same ingredients as HPLC or 3) a MPMC, high fiber, "metabolic" (MET) diet (30% of ME from protein, 37% of ME from NFE) as a commercial control. An echocardiogram and a 12-h glucose, insulin and glucagon response and 6-h AA meal response were performed on day 42 of feeding. Data were analyzed using proc glimmix in SAS (version 9.4). All echocardiographic parameters remained within a healthy reference range for dogs of this size. Dogs fed HPLC had a larger net area under the curve (NetAUC) for plasma glucagon (P < 0.001) compared to dogs fed MPMC and MET, a smaller NetAUC for glucose: insulin (P = 0.039) compared to dogs fed MPMC but MET was similar to both. Glucose NetAUC tended to be different among treatments (P = 0.057), where dogs fed MPMC had a greater netAUC than dogs fed HPLC and dogs fed MET tended to have a greater netAUC than HPLC. Dogs fed HPLC had greater concentrations of Ile, Leu, Lys, Thr, Tyr and Val over time compared to dogs fed MPMC and MET, and dogs fed MET had greater concentrations of Gln and Met over time compared to dogs fed HPLC and MPMC (P < 0.05). Dogs fed a HPLC diet may have improved glucose uptake compared to dogs fed a MPMC diet. This research provides the first insight into the cardiometabolic health of dogs consuming three diets differing in their protein, carbohydrate and fiber content.

Echocardiographic estimates of stroke volume in healthy dogs: comparability, reference intervals, and reproducibility

INTRODUCTION

This study aimed to compare estimates of stroke volume (SV) from different anatomic sites and to generate reference intervals for indices such as shunt volume (ShuntVol) or regurgitant volume (RegVol) in a large sample of healthy dogs.

ANIMALS, MATERIALS AND METHODS

Ninety healthy dogs underwent an echocardiogram, where SV was assessed at the level of the pulmonary valve (SVPV), aortic valve (SVAV), mitral valve (SVMV), and left ventricle using the difference in end-diastolic volume and end-systolic volume from a right parasternal long-axis four-chamber view (SVLV_RPLx) and left apical four-chamber view (SVLV_Ap4Ch). Eight dogs underwent repeated echocardiograms by the same operator on three different days and by three different operators on the same day. Bland-Altman plots and 95% reference intervals were generated. Reproducibility was described using coefficients of variation and reproducibility coefficients.

RESULTS

Mean differences (95% limits of agreement) for ShuntVol (SVPV-SVAV), RegVolLV_RPLx (SVLV_RPLx-SVAV), RegVolLV_Ap4Ch (SVLV_Ap4Ch-SVAV), and RegVolMV (SVMV-SVAV) were as follows: -0.14 (-0.72, 0.44), -0.05 (-0.59, 0.48), -0.16 (-0.71, 0.39), and 0.12 (-0.76, 1.00) mL/kg, respectively. All but RegVolLV_RPLx showed significant (P<0.01) fixed bias. Reference intervals for ShuntVol, RegVolLV_RPLx, RegVolLV_Ap4Ch, and RegVolMV were as follows: -0.85-0.64, -0.65-0.58, -0.77-0.52, and -0.91-1.06 mL/kg, respectively. Intra-operator and interoperator coefficients of variation were lowest for SVAV and highest for SVMV and SVLV_AP4Ch.

CONCLUSIONS

Echocardiographic estimates of SV are not interchangeable and can exhibit wide limits of agreement. Reference intervals help provide a frame of reference to assess disease severity in dogs with a shunting lesion (ShuntVol) and mitral regurgitation (RegVol).

Effect of additional dimensions and views in the echocardiographic determination of 3-dimensional left ventricular volume in myxomatous mitral valve disease in dogs

BACKGROUND

Left ventricular (LV) volumes can be calculated from various linear, monoplane, and multiplane echocardiographic methods, and the same method can be applied to different imaging views. However, these methods and their variations have not been comprehensively evaluated against real-time 3-dimensional echocardiography (RT3D).

HYPOTHESIS/OBJECTIVES

To identify the LV volumetric approaches that produce the least bias and the best agreement with RT3D, and to assess interoperator reproducibility between an experienced and an inexperienced operator.

ANIMALS

Fifty-nine client-owned dogs with myxomatous mitral valve disease (38 Stage B1, 13 Stage B2, 8 Stages C/D) received echocardiograms, with a subset of 28 dogs (14 Stage B1, 10 Stage B2, 4 Stages C/D) imaged by 2 operators.

METHODS

Prospective method comparison study. Body weight-indexed end-diastolic and end-systolic LV volumes using linear methods in long- and short-axis views (Teichholz, cube, modified cube), monoplane methods in right parasternal and left apical views (area-length and Simpson's method of discs), biplane Simpson's method of discs, and real-time triplane (RT3P) were compared against RT3D.

RESULTS

The RT3P method exhibited no bias and demonstrated the highest agreement with RT3D. The linear methods showed significant bias and lower agreements for end-diastolic volumes, end-systolic volumes, or both. Volumes derived from different imaging views using the same method showed poor agreement. Both RT3P and RT3D methods demonstrated poor interoperator reproducibility.

CONCLUSIONS AND CLINICAL IMPORTANCE

Incorporating additional dimensions improves bias and agreement in LV volume quantification, but comprehensive clinical experience with RT3P and RT3D is needed to improve consistency across all operators.

Low-profile KA microplug set for transarterial occlusion of patent ductus arteriosus in a small dog: First experience in interventional cardiology

Background

Cardiologists occlud most patent ductus arteriosus (PDA) defects in dogs using the Amplatz® canine duct occluder via a transarterial approach. However, this approach can be problematic in small dogs due to their small femoral artery diameters. In such cases, cardiologists have opted for lower profile devices or use coils or vascular plugs deployed using a more challenging transvenous approach.

Case Description

The present report describes a 1-year-old, 6 kg male Cavalier King Charles Spaniel with a small PDA, which was successfully occluded using the Micro Plug Set (KA Medical, Minneapolis, MN) via a transarterial approach.

Conclusion

This is the first case report in medicine of PDA closure with a KA Micro Plug Set via transarterial approach. This approach, which has been described for PDA closure in a few dozen premature human infants, could be considered as a minimally invasive PDA closure in small dogs by using a transarterial approach. Furthermore, in pediatric cardiology, the use of the device has been described only via a transvenous approach. The information from this case report could inspire a different and simpler approach to human medicine.

Assessing the use of blood microRNA expression patterns for predictive diagnosis of myxomatous mitral valve disease in dogs

Background

Myxomatous mitral valve disease (MMVD) is a common, acquired, and progressive canine heart disease. The presence of heart murmur and current cardiac biomarkers are useful in MMVD cases but are not sufficiently discriminatory for staging an individual patient.

Objectives

This study aimed to conduct a preliminary assessment of canine serum and plasma expression profiles of 15 selected miRNA markers for accurate discrimination between MMVD patients and healthy controls. Additionally, we aim to evaluate the effectiveness of this method in differentiating between pre-clinical (stage B1/B2) and clinical (stage C/D) MMVD patients.

Animals

Client-owned dogs (n = 123) were recruited for the study. Following sample exclusions (n = 26), healthy controls (n = 50) and MMVD cases (n = 47) were analyzed.

Methods

A multicenter, cross-sectional, prospective investigation was conducted. MicroRNA expression profiles were compared among dogs, and these profiles were used as input for predictive modeling. This approach aimed to distinguish between healthy controls and MMVD patients, as well as to achieve a more fine-grained differentiation between pre-clinical and clinical MMVD patients.

Results

Performance metrics revealed a compelling ability of the method to differentiate healthy controls from dogs with MMVD (sensitivity 0.85; specificity 0.82; and accuracy 0.83). For the discrimination between the pre-clinical (n = 29) and clinical (n = 18) MMVD cases, the results were promising (sensitivity 0.61; specificity 0.79; and accuracy 0.73).

Conclusion and clinical importance

The use of miRNA expression profiles in combination with customized probabilistic predictive modeling shows good scope to devise a reliable diagnostic tool to distinguish healthy controls from MMVD cases (stages B1 to D). Investigation into the ability to discriminate between the pre-clinical and clinical MMVD cases using the same method yielded promising early results, which could be further enhanced with data from an increased study population.

Predictive value of left atrial volumes assessed using real-time three-dimensional echocardiography for pulmonary hypertension in dogs with myxomatous mitral valve disease

Introduction

Left atrial volume (LAV) obtained using real-time three-dimensional echocardiography (RT3DE) is an independent predictor of post-capillary pulmonary hypertension (PH) in humans; however, no studies have investigated LAV obtained using RT3DE as a predictor of post-capillary PH in dogs with myxomatous mitral valve disease (MMVD). Therefore, we aimed to evaluate the clinical applicability of LAV obtained using RT3DE compared to that obtained using two-dimensional echocardiography (2DE) in dogs with MMVD, with or without PH.

Methods

Medical records and echocardiographic images of 237 privately owned dogs with naturally occurring MMVD with or without PH were retrospectively reviewed. A total of 49 privately owned dogs with naturally occurring MMVD, with or without PH, were finally included (35 MMVD without PH, 14 MMVD with PH). The LAV and left ventricular volumes were obtained using 2DE and RT3DE. Echocardiographic parameters were analyzed to identify independent predictors of post-capillary PH.

Results

We found that the left atrial and left ventricular volumes obtained using 2DE and RT3DE indexed to body weight and several 2DE-derived variables were univariately associated with post-capillary PH. Furthermore, multivariable logistic regression analysis revealed that the RT3DE minimum LAV indexed to body weight (LAVi min) was the only significant independent predictor of post-capillary PH (odds ratio, 12.86; 95% confidence interval [CI], 2.40-68.99; p = 0.003), with the highest area under the curve value of 0.86 (95% CI, 0.75-0.96; p < 0.001).

Discussion

In conclusion, LAV indexed to body weight obtained using 2DE and RT3DE, can be a useful predictor of post-capillary PH in dogs with MMVD. In particular, the RT3DE LAVi min was observed to be the strongest predictor of post-capillary PH.

Comparative study of echocardiographic parameters in healthy and dilated cardiomyopathy-affected dogs

Echocardiography is a non-invasive and gold standard imaging tool for diagnosing dilated cardiomyopathy (DCM) in dogs. This study aimed to compare the echocardiographic parameters between healthy and DCM-affected dogs. A total of 52 client-owned dogs, comprising 38 males and 14 females, were included. Among these, 24 dogs (46.15%) were classified as healthy controls and 28 dogs (53.85%) were part of DCM group. On breed-wise prevalence, it was reported that Labrador Retriever breeds showed a higher incidence of DCM than the others. The comparative studies of echocardiographic parameters showed that DCM-affected dogs had significantly higher values in left ventricular long axis length at -end diastole (LVLdA4C) and -end systole (LVLsA4C), end diastolic volume (EDV), end systolic volume (ESV), left atrium (LA)/aorta diameter (Ao) ratio, left ventricular internal dimension at systole (LVIDs), and end point septal separation (EPSS), as well as significantly lower values in left ventricular contractibility indices such as fractional shortening (FS) and ejection fraction (EF) compared to healthy dogs. Also, receiver operating characteristic curves were made to determine the optimal cut-off points for each echocardiographic parameter with specificity and sensitivity for diagnosing DCM. Significant areas under the curve were observed for parameters such as LVIDs, EF, FS, LA/Ao, EPSS, LVLdA4C, LVLsA4C, left ventricular EDV, left ventricular ESV, and ESV for DCM-affected dogs. This cut-off value can be used as an early diagnosis of DCM through echocardiography, facilitating timely clinical interventions and management strategies for improved quality of life in dogs.

The impact of intravenous medetomidine and vatinoxan on echocardiographic evaluation of dogs with stage B1 mitral valve disease

INTRODUCTION/OBJECTIVE

The purpose of this study was to investigate the echocardiographic effects of intravenous medetomidine and vatinoxan in dogs with stage B1 mitral valve disease. We hypothesised medetomidine-vatinoxan would reduce the need for manual restraint during echocardiography without producing detrimental cardiovascular effects or echocardiographic changes.

ANIMALS

Twelve client-owned dogs with stage B1 mitral valve disease.

METHODS

A transthoracic echocardiographic examination was performed before and after sedation with intravenous medetomidine (10 μg/kg) and vatinoxan (200 μg/kg). Vital parameters were also recorded, and the level of sedation was assessed subjectively. The data were analysed with Student's t-tests with an alpha level of <0.05.

RESULTS

End-systolic volume and left ventricular systolic diameter increased (from 0.89 ± 0.19 mL/kg to 1.13 ± 0.29 mL/kg and 0.96 ± 0.12 cm to 1.10 ± 0.10 cm, respectively) and ejection fraction (from 66.33 ± 4.0% to 56.23 ± 9.54%) and fractional shortening (from 36.13 ± 5.42% to 27.24 ± 5.6%) decreased significantly after sedation. End diastolic volume, left ventricular diastolic diameter, and left atrial size remained statistically unchanged, while aortic (from 1.34 ± 0.2 m/s to 0.99 ± 0.14 m/s) and pulmonic (from 0.94 ± 0.16 m/s to 0.66 ± 0.15 m/s) velocities decreased significantly. No dogs had a mean arterial pressure below 65 mmHg. Sedation enabled echocardiographic examination without manual restraint. No adverse effects were observed with the dose studied.

CONCLUSIONS

Echocardiographic parameters were not completely comparable with the baseline values, which should be taken into consideration when evaluating dogs sedated with intravenous medetomidine-vatinoxan.

Use of two- and three-dimensional echocardiography for assessment of the left ventricular outflow tract and aortic orifice areas in dogs

INTRODUCTION/OBJECTIVES

In clinical practice, dogs are screened for subaortic stenosis (SAS) using two-dimensional (2DE) and Doppler echocardiography. There is no accepted antemortem diagnostic criterion to distinguish between mild SAS and unaffected, therefore additional means of evaluating the left ventricular outflow tract (LVOT) and aorta may be desirable. This study sought to determine and compare LVOT and aortic orifice areas using 2DE and three-dimensional echocardiography (3DE) in apparently healthy dogs of various breeds and somatotypes.

ANIMALS, MATERIALS, AND METHODS

Sixty-nine healthy, privately-owned dogs. The LVOT and aortic orifice areas were determined using 2DE aortic valve (AV) diameter-derived area; the continuity equation (CE); and 3DE planimetry of the LVOT, AV, sinus of Valsalva, and sinotubular junction. Orifice areas were indexed to body surface area (BSA).

RESULTS

Obtaining 3DE images and performing planimetry were feasible in all dogs. The mean indexed area measured using the 2DE AV diameter (2.85 cm2/m2) was significantly lower than that derived from 3DE AV planimetry (3.85 cm2/m2; mean difference, 1.00 cm2/m2; P<0.001). There was poor agreement between the effective area calculated using the CE and the anatomic areas calculated using 2DE AV diameter and 3DE planimetry. The area calculated using the CE was less than all other calculations of area. Interobserver and intraobserver repeatability and reproducibility for 3DE planimetry were excellent.

CONCLUSIONS

Methods for determining aortic orifice areas in dogs are not interchangeable, and this must be taken into account if these methods are investigated in the evaluation of dogs with SAS in the future.

Doppler Ultrasonographic Assessment of Abdominal Aortic Flow to Evaluate the Hemodynamic Relevance of Left-to-Right Shunting Patent Ductus Arteriosus in Dogs

In this multicenter, prospective, observational study, abdominal aortic flow was examined with pulsed-wave Doppler ultrasound in dogs with a left-to-right shunting patent ductus arteriosus (PDA) and in apparently healthy dogs. Forty-eight dogs with a PDA and 35 controls were included. In the dogs with a PDA, 37/48 had hemodynamically significant PDAs (hsPDAs) while 11/48 had non-hsPDAs, based on the presence or absence of echocardiographic signs of left-sided volume overload, respectively. In 12 dogs (4/35 control dogs, 7/37 dogs with an hsPDA and 1/11 dogs with a non-hsPDA), the diastole was too short to visualize the end-diastolic flow. Antegrade end-diastolic flow was observed in 30/35 controls and 6/11 dogs with a non-hsPDA. Absent end-diastolic flow was observed in 1/35 control dogs and 3/11 dogs with a non-hsPDA. Retrograde end-diastolic flow was observed in 30/37 dogs with an hsPDA and 1/11 dogs with a non-hsPDA. Twenty-one dogs (15 with an hsPDA and 6 with a non-hsPDA) were reassessed after PDA closure, and, in 19/21, end-diastolic flow was visualized: 17/19 showed an antegrade flow, 1/19 an absent flow and 1/19 a retrograde flow. Sensitivity and specificity of retrograde end-diastolic flow for detection of hsPDAs were 100% and 90%, respectively. In conclusion, ultrasonographic assessment of abdominal aortic flow was feasible in dogs with PDA. However, end-diastolic flow was not always visualized. The presence of a retrograde end-diastolic flow was an accurate finding for discriminating hsPDAs and non-hsPDAs.

A Pilot Study of the Role of Selected Biomarkers of Kidney Injury in Dogs with Dilated Cardiomyopathy

Heart and kidney diseases are among the most frequent medical conditions diagnosed in small animals. Due to the functional interconnection between these organs, the concept of the cardio-renal axis has been developed. In this context, renal disease or dysfunction often occurs secondary to heart diseases, such as dilated cardiomyopathy (DCM). DCM is the most common cardiomyopathy and a leading cause of mortality in large-breed dogs. Traditional biomarkers like creatinine or symmetric dimethylarginine concentration are not always effective, especially in the early stages of the disease, underscoring the need for more sensitive markers of renal impairment during heart failure (HF). This study aimed to evaluate the efficacy of selected biomarkers as indicators for early kidney damage in dogs with stage B2 DCM. We measured serum concentrations of cystatin C, KIM-1 (kidney injury molecule-1), and NGAL (neutrophil gelatinase-associated lipocalin) and their ratios to creatinine, analyzing their diagnostic values. Cystatin C was quantified using a sandwich enzyme immunoassay, while KIM-1 and NGAL were measured with enzyme-linked immunosorbent assay kits designed for canine diagnostics. The concentrations were indexed against serum creatinine. The study included 26 dogs: 9 with HF and 17 healthy controls. The mean ± standard deviation for healthy dogs for cystatin C, cystatin C/creatinine ratio, KIM-1, KIM-1/creatinine ratio, NGAL, and NGAL/creatinine ratio were 0.24 ± 0.04, 0.26 ± 0.07, 0.61 ± 0.07, 0.67 ± 0.13, 2.76 ± 1.8, and 2.79 ± 1.81, respectively. For DCM dogs, these values were 0.27 ± 0.1, 0.32 ± 0.12, 0.61 ± 0.08, 0.69 ± 0.17, 6.46 ± 5.22 (p = 0.02), and 7.99 ± 6.53 (p = 0.04). This study's findings suggest that during the asymptomatic phase of DCM, only NGAL concentration and the NGAL/creatinine ratio may serve as diagnostic markers for early-stage kidney injury.

Reference intervals for various measurements of canine left atrial size and function obtained using two-dimensional and three-dimensional echocardiography

BACKGROUND

Many canine cardiac diseases are associated with left atrial (LA) remodeling and decreased function. For accurate assessment of LA indices, large-scale and prospectively determined reference intervals are necessary.

OBJECTIVES

To generate reference intervals of LA size and function using two-dimensional and three-dimensional echocardiography.

ANIMALS

Two hundred and one healthy adult dogs.

METHODS

Left atrial volume was assessed in right parasternal long-axis, left apical 4-chamber and 2-chamber views using monoplane Simpson's method, two-dimensional and three-dimensional speckle tracking. Additionally, LA diameter was measured in right parasternal short-axis and long-axis views. Furthermore, LA function was determined by measuring strain and calculating LA fractional shortening and ejection fraction. All variables were tested for correlation to heart rate, age, and body weight. For LA diameter and volume, scaling exponents and prediction intervals were generated using allometric scaling. Reference intervals for LA function parameters were calculated using nonparametric methods.

RESULTS

Left atrial diameter and volume showed a strong correlation with body weight. The scaling exponent for LA diameter was approximately 1/3 (0.34-0.40) and approximately 1 for volume measurements (0.97-1.26). Parameters of LA function showed no clinically relevant correlation with body weight, except for two variables, which showed a mild negative correlation. No clinically relevant correlations with age or heart rate were found.

CONCLUSIONS

Reference intervals for linear, two-dimensional and three-dimensional measurements of LA size and function were established. The wide range of measurement methods offers the opportunity to select the appropriate reference values for LA evaluation depending on the available technical possibilities.

Echocardiographic reference intervals of the dimensions of the main pulmonary artery and the right pulmonary artery: a prospective study in 269 healthy dogs

INTRODUCTION

No data are available on the echocardiographic reference intervals (RIs) for the main pulmonary artery (MPA) and right pulmonary artery (RPA) dimensions in a large sample of dogs. Therefore, we aimed to describe the echocardiographic RIs of the MPA and RPA dimensions in normal dogs.

ANIMALS, MATERIALS, AND METHODS

Two hundred and sixty nine healthy dogs of different breeds, age and body weight (BW) were prospectively enrolled in this multicenter, observational study. The MPA diameter, RPA maximum diameter (RPAmax), and RPA minimum diameter (RPAmin) were measured from the right parasternal short axis view. Prediction intervals (PIs) for MPA, RPAmax and RPAmin were generated using allometric scales. Reference intervals (RI) of MPA indexed to the ascending aorta (MPA/AO), and RPAmax and RPAmin indexed to the aortic annulus (RPAmax/Aod and RPAmin/Aod), were defined.

RESULTS

A positive linear relationship between MPA, RPAmax, RPAmin and BW was evident after logarithmic transformation (R2 = 0.859, R2 = 0.787 and R2 = 0.725, respectively; P<0.0001). According to allometric scales, the PI for the MPA normalized for BW (MPA_N) was between 5.50 and 8.07, the PI for the RPAmax normalized for BW (RPAmax_N) was between 3.23 and 5.62, while the PI for the RPAmin normalized for BW (RPAmin_N) was between 1.62 and 3.30. The median MPA/AO was 0.92 (RI, 0.78-1.01), the median RPAmax/Aod was 0.70 (RI, 0.53-0.98) and the median RPAmin/Aod was 0.40 (RI, 0.29-0.61).

DISCUSSION AND CONCLUSIONS

The reported RIs of the MPA and RPA dimensions in normal dogs could increase the diagnostic accuracy of transthoracic echocardiography in the identification of pulmonary artery enlargement in dogs.

Pulmonary arteriovenous malformation and a concurrent patent ductus arteriosus in a Doberman

A 7-week-old male Doberman presented with tachypnea, dyspnea and a VI/VI, left cranial, continuous heart murmur. Thoracic radiographs revealed severe left-sided cardiomegaly, presence of a rounded soft tissue opacity in the caudodorsal aspect of the thoracic cavity and signs of left-sided congestive heart failure. Clinical signs of heart failure were medically controlled. Echocardiography and computed tomography demonstrated a left-to-right shunting patent ductus arteriosus (PDA) in combination with a right-to-left shunting pulmonary arteriovenous malformation (PAVM) between the right main pulmonary artery and the right caudal pulmonary vein. Arterial blood gasses revealed mild hypoxemia. Transcatheter occlusion of the PDA using an Amplatz Canine Duct Occluder was performed. Four months post-operatively, echocardiography showed normal cardiac size and function with complete PDA closure. Thoracic radiographs revealed absence of the rounded opacity and resolution of cardiomegaly and vascular congestion. The PAVM was no longer visualized on repeated computed tomography and the arterial blood gasses were within normal limits. A PAVM connecting a pulmonary artery to a pulmonary vein has only rarely been reported in dogs. This report describes the presence of a congenital PAVM in combination with a PDA in a dog, which has not been previously reported in veterinary medicine.

Surgical correction of an infundibular pulmonic stenosis and ventricular septal defect in a Shetland Sheepdog

A four-month-old male Shetland Sheepdog presented with exercise intolerance. Physical examination revealed an IV/VI left cranial systolic heart murmur. Echocardiography showed a severe infundibular pulmonic stenosis and a concomitant restrictive ventricular septal defect. As clinical signs of congestive right-sided heart failure worsened and were refractory to medical treatment, surgical correction was advised. Via sternotomy, with cardiopulmonary bypass and cardioplegic cardiac arrest, ventricular septal defect closure and resection of the stenotic infundibular band were performed through right ventriculotomy, followed by patch enlargement. Postoperative recovery was uneventful and echocardiography showed complete resolution of the stenosis and successful closure of the ventricular septal defect. Follow-up echocardiography revealed restenosis after seven weeks and recurrence of right-sided heart failure three months postoperatively. Stenting of the restenosis was attempted via a hybrid procedure with sternotomy and direct transventricular approach. The dog developed fatal ventricular fibrillation during stent deployment. This is the first dog in which surgical right ventricular patch enlargement under cardiopulmonary bypass is reported for the treatment of a primary infundibular pulmonic stenosis.

Echocardiographic values in healthy Pugs: Effect of body weight, age, and sex

Background

Transthoracic echocardiography represents the main noninvasive technique for evaluating cardiac morphology and function in dogs. In dogs with particular somatotypes, such as brachymorphic dogs, breed-specific echocardiographic values are needed for a proper echocardiographic interpretation. Nowadays, the Pug represents one of the most popular brachymorphic canine breeds worldwide. However, data on echocardiographic measurements in this breed are currently limited.

Aim

We aimed to determine echocardiographic values in a population of apparently healthy Pugs, and to assess the possible effects of body weight (BW), age, and sex on selected echocardiographic variables, with particular emphasis on those related to the left-sided cardiac chambers.

Methods

Apparently healthy Pugs underwent a full physical examination, a 1-minute six-lead electrocardiogram, and a complete transthoracic echocardiography. Twenty-four echocardiographic variables were measured by combining M-mode, two-dimensional and Doppler modalities, and relative values were determined by applying the statistical procedures recommended by the Clinical and Laboratory Standards Institute. Moreover, the effect of selected demographic variables on echocardiographic measurements was tested using a linear mixed model.

Results

The investigation included 86 Pugs. Echocardiographic values were provided for each variable and compared with previous veterinary literature. A statistically significant effect of BW, age, and sex was documented for several of the tested variables. Doppler examination demonstrated a trivial pulmonary regurgitation in 24/86 (27.9%) Pugs. Moreover, a persistent left cranial vena cava was suspected in 4/86 (4.7%) dogs.

Conclusion

Echocardiographic features of the Pug were addressed and echocardiographic values were made available for clinical use. Because our findings were obtained using a standardized echocardiographic analysis in a population of 86 healthy Pugs, they may act as a reliable guide for an accurate echocardiographic interpretation in this breed.

Cardiological Reference Intervals in Adult American Staffordshire Terrier Dogs

The aim of this study was to determine reference intervals (RI) for echocardiography, electrocardiography (ECG), vertebral heart score (VHS) measurement, and arterial systolic blood pressure (SBP) in American Staffordshire Terrier dogs. The study population included 29 clinically healthy AST dogs of different ages, genders, and body weights. SBP measurement, ECG, thoracic radiography, and echocardiography were performed on each dog. Compared to RIs available for the general population of dogs, the duration of the P wave and QRS complex was longer and VHS was higher. Moreover, the left ventricular dimension in diastole and systole, left atrial dimension, and end point to septal separation values were higher, while the interventricular septum in diastole and systole and aortic root diameter were lower compared to general similar average body weight. The AST breed has a different heart shape, which in this breed is more rounded compared to other dog breeds, especially the deep chest. The specific body structure and the shape of the heart had an impact on the results of the cardiological examination.

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.

Effects of a 28-day feeding trial of grain-containing versus pulse-based diets on cardiac function, taurine levels and digestibility in domestic dogs

In 2018, the US Food and Drug Administration reported a link between canine dilated cardiomyopathy (DCM) and grain-free diets. Evidence to support a link has emerged, but the specific ingredients responsible and the role of taurine or other causative factors remain unclear. We hypothesized dogs fed pulse-based, grain-free diets for 28 days will show decreased macronutrient digestibility, increased fecal bile acid excretion, and reduced plasma cystine, cysteine, methionine and taurine, causing sub-clinical cardiac or blood changes indicative of early DCM. Three diets were formulated using white rice flour (grain), whole lentil (grain-free), or wrinkled pea (grain-free) and compared to the pre-trial phase on a commercial grain-based diet. After 28 days of feeding each diet, the wrinkled pea diet impaired stroke volume and cardiac output, increased end-systolic ventricular diameter and increased plasma N-Terminal Pro-B-type Natriuretic Peptide (NT-ProBNP), albeit in a sub-clinical manner. Digestibility of some macronutrients and sulphur-containing amino acids, excluding taurine, also decreased with pulse-based compared to grain-based diets, likely due to higher fiber levels. Plasma taurine levels were unchanged; however, plasma methionine was significantly lower after feeding all test diets compared to the commercial diet. Overall, DCM-like changes observed with the wrinkled pea diet, but not lentil diet, after only 4 weeks in a breed not known to be susceptible support a link between pea-based diets and canine nutritionally-mediated DCM.

The Pulse of It: Dietary Inclusion of Up to 45% Whole Pulse Ingredients with Chicken Meal and Pea Starch in a Complete and Balanced Diet Does Not Affect Cardiac Function, Fasted Sulfur Amino Acid Status, or Other Gross Measures of Health in Adult Dogs

BACKGROUND

Pulses are an attractive alternative protein source for all mammals; however, recent reports suggest that these ingredients may be related to developing dilated cardiomyopathy in dogs.

OBJECTIVES

The primary objective of this study was to quantify the effects of dietary pulse intake by adult dogs on cardiac function using echocardiographic measurements and cardiac biomarkers N-terminal pro-B-type natriuretic peptide and cardiac troponin I (cTnI). Second, to investigate the effects of pulse consumption on plasma sulfur amino acid (SAA) concentrations as pulses are generally low in SAA and may limit taurine synthesis. Last, to assess the general safety and efficacy of feeding pulse-containing diets on canine body composition and hematological and biochemical indices.

METHODS

Twenty-eight privately-owned domestic Siberian Huskies (13 females; 4 intact, and 15 males; 6 intact) with a mean age of 5.3 ± 2.8 y (± SD) were randomly assigned to 1 of 4 dietary treatments (n = 7/treatment), with equal micronutrient supplementation and increasing whole pulse ingredient inclusion (0%, 15%, 30%, and 45%) with pea starch used to balance protein and energy.

RESULTS

After 20 wks of feeding, there were no differences (P > 0.05) in echocardiographic parameters, N-terminal pro-B-type natriuretic peptide, and cTnI concentrations among treatments or across time within treatment (P > 0.05), indicating no differences in cardiac function among treatments. Concentrations of cTnI remained below the safe upper limit of 0.2 ng/mL for all dogs. Plasma SAA status, body composition, and hematological and biochemical indices were similar among treatments and over time (P > 0.05).

CONCLUSIONS

The results from this study suggest that increasing the inclusion of pulses up to 45% with the removal of grains and equal micronutrient supplementation does not impact cardiac function concurrent with dilated cardiomyopathy, body composition, or SAA status and is safe for healthy adult dogs to consume when fed for 20 wks.

Echocardiographic values for normal conditioned and unconditioned North American whippets

BACKGROUND

Echocardiographic reference intervals have not been reported for North American whippets, or for whippets that have undergone pet-level athletic training.

OBJECTIVES

To develop normal echocardiographic reference intervals for North American whippets and investigate differences in echocardiographic parameters based on athletic conditioning in pet whippets engaged in competitive sports.

ANIMALS

One-hundred healthy North American whippets.

METHODS

Dogs were examined at national shows between 2005 and 2009. Echocardiographic reference intervals were constructed and the effect of athletic conditioning on parameters of structure and function was assessed.

RESULTS

Two dimensional, M-mode, Doppler and tissue Doppler reference ranges for healthy North American whippets are presented. Measures of left ventricular (LV) chamber diameter were larger in conditioned whippets (N = 25) and remained significantly larger than in unconditioned whippets (N = 16) when normalized for weight using allometric equations. Calculated LV mass was higher in conditioned dogs than in unconditioned dogs, and this difference persisted when LV mass was normalized by weight. Mitral E velocity was higher in conditioned dogs than in unconditioned dogs, whereas E/A and measures related to systolic function were not different.

CONCLUSIONS AND CLINICAL IMPORTANCE

Pet whippets in peak athletic condition have larger hearts than do less conditioned whippets, but measures of systolic function are similar. Whippet pet athletes may show eccentric LV hypertrophy at peak condition. Normal values for cardiac size and function in North American whippets might be considered abnormal if population-specific whippet reference intervals are not used in analysis.

A multicenter, retrospective study of cardiac disease in Borzoi dogs

Borzoi are large, relatively uncommon sighthounds anecdotally reported to suffer from sudden death. This multicenter retrospective cohort study aimed to describe the sample of Borzoi presenting to veterinary cardiologists for evaluation, with records searched from 14 centers across a study period of up to 20 years. The study sample was comprised of 152 client-owned Borzoi, with dogs most commonly presenting for pre-breed screening in 87/152 (52%), followed by evaluation of an arrhythmia in 28/152 (18%). Of the 131/152 (86%) dogs that had an echocardiogram performed, 85/131 (65%) were structurally normal, with 40/85 (47%) structurally normal dogs having trace or mild atrioventricular valve regurgitation. Tricuspid valve dysplasia was the most commonly diagnosed congenital cardiac disease (n = 6). Myxomatous mitral valve disease (n = 12) and dilated cardiomyopathy (n = 13) were diagnosed at similar frequencies, though 92% of valve disease cases were mild. Only 48/152 (32%) Borzoi had a diagnostic electrocardiogram (ECG) and/or a Holter monitor for arrhythmia screening. Despite this, ventricular arrhythmias were identified during the entirety of the available cardiac evaluation including diagnostic ECG, contemporaneous ECG monitoring during the echocardiogram, and/or Holter monitor in 25/131 (19%) dogs in which an echocardiographic diagnosis was available. Of these 25 Borzoi, 76% had minimal or no structural cardiac disease identified, and five had a family history of sudden death. A sudden death outcome was reported in 3/55 (5%) Borzoi with long-term outcome data available. In conclusion, Borzoi commonly have trace or mild atrioventricular valve insufficiencies, and may develop ventricular arrhythmias and dilated cardiomyopathy.

Comparison of echocardiographic measurements and cardiac biomarkers in healthy dogs eating nontraditional or traditional diets

BACKGROUND

There has been a recent association between nontraditional diets and development of diet-associated dilated cardiomyopathy (DCM) in dogs.

HYPOTHESIS/OBJECTIVES

To compare echocardiographic measurements and cardiac biomarkers between healthy dogs eating nontraditional vs traditional diets. We hypothesized that dogs eating nontraditional diets would have lower measures of systolic myocardial performance compared to dogs eating traditional diets.

ANIMALS

Forty-six healthy dogs: 23 eating nontraditional diets and 23 eating traditional diets.

METHODS

Prospective, cross-sectional study. Dogs were divided into groups based on diet ingredients. Dogs underwent 2-dimensional (2D), 3-dimensional (3D), and Doppler echocardiographic examinations and analysis of plasma N-terminal prohormone of B-type natriuretic peptide, serum cardiac troponin I, and whole blood and plasma taurine concentrations.

RESULTS

Mean 2D ejection fraction (EF) was lower for dogs eating nontraditional diets (48.65 ± 7.42%) vs dogs eating traditional diets (56.65 ± 4.63%; P < .001; mean difference 8.0% [4.0%-12.0%] 95% confidence interval [CI]). Mean 3D EF was lower for dogs eating nontraditional diets (45.38 ± 7.35%) vs dogs eating traditional diets (57.58 ± 4.84%; P < .001; 12.0% [8.0%-16.0%] 95% CI). Mean 2D left ventricular end-systolic volumes, indexed to body weight, were significantly higher in dogs eating nontraditional diets (1.46 ± 0.08 mL/kg) vs dogs eating traditional diets (1.06 ± 0.08 mL/kg; P = .002; 0.4 mL/kg [0.18-0.62 mL/kg] 95% CI).

CONCLUSIONS AND CLINICAL IMPORTANCE

Healthy dogs eating nontraditional diets had lower indices of systolic function and larger left ventricular volumes compared to dogs eating traditional diets. Screening of apparently healthy dogs eating nontraditional diets might allow for early detection of diet-associated DCM.

Prevalence and prognostic role of L wave and selected clinical and echocardiographic variables in dogs with atrial fibrillation

BACKGROUND

Information regarding the frequency of L waves and their prognostic relevance in dogs with secondary atrial fibrillation (AF) is limited.

HYPOTHESIS/OBJECTIVES

To determine whether L waves occur and ascertain their prognostic role, as well as the role of other clinical and echocardiographic variables in dogs with AF.

ANIMALS

Fifty-five dogs with AF associated with myxomatous mitral valve disease or dilated cardiomyopathy.

METHODS

Retrospective, multicenter observational study. In addition to L waves analysis, other clinical and echocardiographic variables, including type of antiarrhythmic treatment, were evaluated. A survival analysis was performed to test for predictors of cardiac death and all-cause mortality using Cox proportional hazards regression models.

RESULTS

L waves were evident in 33/55 dogs (60%, 95% confidence interval [CI] = 47%-72%) but their presence did not influence outcome. Increased left ventricular end-systolic diameter normalized for body weight (LVSDn) was a significant predictor of both cardiac death (hazard ratio [HR] = 4.41, 95% CI = 1.18-16.54; P = .03) and all-cause mortality (HR = 9.39, 95% CI = 2.49-35.32; P < .001). Heart rate assessed during echocardiography (Echo-HR) represented an additional significant predictor of cardiac death (HR = 1.01, 95% CI = 1.00-1.01; P = .04) and all-cause mortality (HR = 1.01, 95% CI = 1.00-1.01; P = .04).

CONCLUSIONS AND CLINICAL IMPORTANCE

L waves occurred frequently in dogs with AF, but held no prognostic relevance. Conversely, LVSDn and Echo-HR represented independent predictors of negative outcome in these animals.

The effect of obesity and subsequent weight reduction on cardiac structure and function in dogs

Background

In people, the cardiovascular effects of obesity include systemic hypertension, cardiac remodelling and both systolic and diastolic dysfunction, whilst weight reduction can reverse myocardial remodelling and reduce risk of subsequent cardiovascular disease. To date, variable results are reported in studies of the effect of obesity and controlled weight reduction on cardiovascular morphology and function in dogs. This prospective study aimed to assess cardiac function, heart rate variability, cardiac biomarkers and body composition before and after weight reduction in pet dogs with obesity. Twenty-four client-owned dogs referred for weight management due to obesity were recruited. To assess the cardiac effects of obesity, body composition analysis (by dual energy X-ray absorptiometry, DEXA) and cardiovascular assessment (echocardiography, Doppler blood pressure, electrocardiography, cardiac biomarkers) were performed prior to weight management. Twelve dogs completed the study and reached target weight, receiving a further cardiovascular assessment and DEXA. A Wilcoxon-signed rank test was used to compare each variable pre- and post- weight reduction.

Results

Median (interquartile range) duration of weight loss was 224 days (124–245 days), percentage weight loss was 23% (18–31%) of starting weight. Median change in body fat mass was -50% (-44% to -55%; P = 0.004), whilst median change in lean mass was -7% (+ 1% to -18%, P = 0.083).

Before weight reduction, diastolic dysfunction (evidence of impaired relaxation in all dogs), increased left ventricular wall thickness and mildly elevated systolic blood pressure (14/24 ≥ 160 mmHg, median 165 mmHg (140–183)) were common features in dogs with obesity. However, systolic left ventricular wall dimensions were the only variables that changed after weight reduction, with a decrease in both the systolic interventricular septum (P = 0.029) and systolic left ventricular free wall (P = 0.017). There was no evidence of decreased heart rate variability in dogs with obesity (P = 0.367), and no change in cardiac biomarker concentrations with weight reduction (N-terminal proBNP, P = 0.262; cardiac troponin I P = 0.657).

Conclusions

Canine obesity results in diastolic dysfunction and left ventricular hypertrophy, the latter of which improves with significant weight and fat mass reduction. Further studies are required to clarify the clinical consequences of these findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03449-4.

Screening for dilated cardiomyopathy in dogs

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiac disease in large breed dogs. The disease can start with arrhythmias or with systolic dysfunction of the myocardium.

OBJECTIVE

To describe screening methods for DCM in various breeds and provide a new, modified staging system.

RECOMMENDATIONS

Screening for occult DCM should start at three years of age and use Holter monitoring in Boxers and Dobermans and might be useful also in other breeds. Single ventricular premature complexes (VPCs) can be detected in many healthy dogs, but healthy animals typically have <50 VPCs in 24 h and demonstrate minimal complexity most often occurring only as single ectopic beats. In general, >100 VPCs in 24 h was recommended as the cut-off value for establishing a diagnosis of DCM. However, there are breed-specific recommendations related to Holter recording diagnosis of DCM in Dobermans and Boxers. Yearly screening over the life of a dog is recommended, as a one-time screening is not sufficient to rule out the future development of DCM. Several echocardiographic methods such as M-mode derived measurements, the measurement of the left ventricular (LV) volume by Simpson's method of discs (SMOD), and E-point to septal separation (EPSS) are recommended for screening purposes. The value of additional tests such as cardiac biomarkers (troponin I and N-terminal pro-B-type natriuretic peptide) as well as a 5-min resting electrocardiogram (ECG) or newer echocardiographic methods such as strain measurements is discussed.

CONCLUSION

This review suggests some guidelines for screening for DCM in various breeds.

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 95^th 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.

Echocardiographic assessment of dilated cardiomyopathy in dogs

Dilated cardiomyopathy (DCM) is a frequent cause of cardiac disability, congestive heart failure (CHF), and arrhythmic death in dogs. The etiology of DCM is usually idiopathic/genetic, but some causes of a DCM phenotype are reversible. The disease is classified into preclinical (occult) and clinical (overt) stages; the latter stems from heart failure with reduced ejection fraction. DCM is further characterized by clinical, electrocardiographic, circulating biomarker, and imaging abnormalities. The diagnosis of clinical DCM with CHF is straightforward; however, identification of the preclinical stage can be challenging. Echocardiography is central to the diagnosis of both stages and characterized by left ventricular (LV) systolic dysfunction with progressive chamber dilation and variable enlargements of the left atrium and right-sided chambers. Left ventricular dilation is defined by increased LV end-diastolic volumes, areas, and internal dimensions normalized to body size or indexed to the aorta. Systolic dysfunction is characterized by decreased LV ejection fraction, increased end-systolic volume, and reduced shortening across minor and longitudinal LV axes. Dyssynchrony can confound the interpretation of linear indices of systolic function. A comprehensive echocardiogram in DCM includes two-dimensional and M-mode studies, spectral and tissue Doppler imaging, and potentially three-dimensional echocardiography and myocardial strain imaging. Echocardiographic findings should be interpreted within the context of identifiable risks and comorbidities, physical diagnosis, complementary diagnostic testing, and limitations of current reference intervals. Ambiguous examinations should be repeated. Specific echocardiographic criteria for the diagnosis of DCM are proposed to encourage discussion and additional outcome and breed-specific echocardiographic studies of canine DCM.

Echocardiographic reference intervals for volumetric measurements of the left ventricle using the Simpson's method of discs in 1331 dogs

Background

Echocardiographic measurements play an important role in detecting cardiac enlargement and assessing cardiac function. In human cardiology, M‐mode measurements have been widely replaced by volumetric measurements of the left ventricle (LV) using Simpson's method of disc (SMOD). In veterinary cardiology, more large‐scale studies are necessary to generate reference intervals (RIs) for SMOD LV volume measurements.

Objective

To generate body size independent RIs for LV volume measurements in dogs.

Animals

Healthy adult dogs (n = 1331) of variable size and somatotype.

Methods

Prospective study. The SMOD was measured from the right parasternal long axis and the left apical 4‐chamber view in clinically healthy dogs. The SMOD measurements were normalized to various allometric scales (kg, kg^2/3, or kg^1/3). RIs for LV end‐diastolic volume (LVEDV) and LV end‐systolic volume (LVESV) using SMOD were estimated as prediction intervals of both a linear and an additive regression model. Additionally, after normalization to body weight, 95% RIs were determined using nonparametric methods with 2.5 and 97.5 percentiles serving as the lower and upper limits. Separate analyses were performed for 120 sighthound breeds and 1211 other breeds.

Results

Echocardiographic LV volumes correlated best with weight in kilograms. The additive model proved to be more flexible and accurate than the other 2 methods to generate RIs. Separate RIs for sighthound and all other breeds are provided.

Conclusions and Clinical Importance

Body size and breed‐independent RIs for LV volume measurements using SMOD were generated prospectively from a large and diverse population of dogs and are available for clinical use.