Prevalence and Characterization of Pulmonary Regurgitation in Normal Adult Dogs

Abnormal movement of the pulmonary valve in dogs diagnosed with patent ductus arteriosus

In the typical left-to-right patent ductus arteriosus (PDA), the shunt flows from the ductus arteriosus towards the pulmonary valve. Although hemodynamic changes have been carefully studied in dogs with PDA, there is very little information on the outcomes of the pulmonary valve after surgical correction of PDA. This study aimed to visualize the pulmonary valve by transthoracic echocardiography in dogs with PDA before and after surgical ligation. Prior to surgery, the movement of the anterior semilunar cusp of the pulmonary valve was obstructed by the shunted blood flow during systole in all nine dogs with PDA in this study. M-mode echocardiography revealed a continuous trajectory of the cusp, because the cusp was pushed towards the right ventricle during the whole cardiac cycle by the shunted flow. Epicardial echocardiography performed in one dog during surgical ligation of the ductus arteriosus revealed that the movement of the anterior semilunar cusp normalized immediately after ligation. B- and M-mode echocardiography may be used to support the diagnosis of PDA through observation of the pulmonary valve when color Doppler echography is not available. The findings in this study may be of importance in distinguishing PDA from PDA-mimicking diseases worth considering before the treatment process (e.g. aorticopulmonary fistulas or aberrant arteriovenous shunts).

ECHOCARDIOGRAPHIC MEASUREMENTS IN ANESTHETIZED CAPTIVE RED PANDAS (AILURUS FULGENS)

A recent review of mortality in captive red pandas (Ailurus fulgens) listed cardiac pathology as the most common cause of death in the adult age group. The aim of this study was to describe the standard echocardiographic variables in 13 captive, healthy, adult red pandas that underwent an elective health examination. In addition, differences between the two subspecies of red panda, A. f. styani than in A. f. fulgens, and association of these echocardiographic variables with age, sex, and body condition score, were examined. Anesthesia was induced and maintained with isoflurane inhalant anesthetic. All animals underwent a full physical examination and comprehensive echocardiogram including 2D, M-mode, and Doppler modes of ultrasound examination. Mean and SD of the echocardiographic variables are reported. Systolic performance was considered subnormal due to the effect of the anesthetic agent. The echocardiographic variables were similar for the two subspecies and sexes, with the exception of the left atrial dimension (2D), which measured larger (P= 0.03) in A. f. styani than in A. f. fulgens, and left ventricular internal diameter in diastole, which measured larger (P = 0.04) in males than females. Several echocardiographic measurements were correlated with age (P < 0.05), whereas the only measurement that significantly correlated with body condition score was end diastolic volume (P = 0.01). These results provide ranges that can offer guidance for predicting cardiac disease in red panda.

Prevalence of Echocardiographic Evidence of Trace Mitral and Aortic Valve Regurgitation in 50 Clinically Healthy, Young Adult Labrador Retrievers without Heart Murmur

Simple Summary

Screening for various disorders lowers the chance for spreading hereditary diseases by selecting individuals for breeding that do not have that specific disorder. Screening examinations, which are typically performed in clinically healthy animals, can pick up diseases in an early stage, when clinical signs are absent. On the other hand, screenings might also reveal anomalies of questionable relevance. In the present study, healthy young Labrador retrievers were screened with cardiac ultrasound for congenital heart defects. In half of the dogs, a small leakage of a cardiac valve was found, which finding is often a sign of a heart disease. However, in this breed and age group, this leaky valve is most likely innocent and represents a variation of normal.

Abstract

Background—Though physiologic regurgitation of the right-sided cardiac valves is well recognized in dogs and other mammals, the prevalence of trace insufficiency of the mitral and aortic valves in clinically healthy, young adult dogs is unknown. Methods—In this observational cross-sectional study, 50 clinically healthy, young adult Labrador retrievers without an audible heart murmur were enrolled. All dogs were bred and owned by a single organization. Cardiac screening was requested for all dogs that were intended for breeding. These dogs underwent a cardiac auscultation and transthoracic echocardiography by a veterinary cardiology specialist. If mitral or aortic valve regurgitation was noticed, the jet size was subjectively assessed on color Doppler echocardiography. Pedigree analysis was performed to reveal a possible hereditary background of mitral valve regurgitation. Results—The prevalence of trivial mitral valve regurgitation was 52% with no significant predisposition to gender (p = 0.86) or haircoat color (p = 0.68). The prevalence of aortic valve regurgitation was 4%. Pedigree analysis for mitral valve regurgitation showed familial clustering, suggesting a hereditary background of the trait. Conclusions—The prevalence of silent trace mitral valve regurgitation in young adult Labrador retrievers was high. Because the regurgitant jet was trivial in all dogs, it is probably physiologic.

Echocardiographic reference intervals in healthy UK deerhounds and prevalence of preclinical dilated cardiomyopathy: a prospective, longitudinal study

BACKGROUND

Sighthounds have high echocardiographic (ECHO) left ventricular volumes. Establishing robust breed-specific ECHO reference intervals (RI) for screening is important. End-diastolic volume index (EDVI), end-systolic volume index (ESVI) and ejection fraction (EF) reference ranges derived by Simpson's method of discs are not available for deerhounds. The influence of sex or body weight (BW) on left ventricular diameter during diastole (LVDd) and systole (LVDs) has never been reported.

OBJECTIVES

Prospectively determine ECHO RI and assess prevalence of dilated cardiomyopathy (DCM) in healthy UK deerhounds.

ANIMALS

Ninety-nine deerhounds.

METHODS

Deerhounds scored on ECHO and ECG variables then classified as normal (NORM), equivocal (EQUIV) or affected (AFF) with DCM. Fifty-nine NORM deerhounds used to determine ECHO RI.

RESULTS

Prevalence of DCM was 21.6%. There were significant differences in BW (p<0.001), LVDd (p<0.001) and LVDs (p<0.05) between female and male deerhounds. Cut-off values for EDVI (≥140.2 mL/m²: 79% sensitivity/97% specificity), ESVI (≥71.9 mL/m²: 94.7% sensitivity/94.2% specificity) and EF (≤42.1%: 84.2% sensitivity/92.8% specificity) were proposed to help diagnose DCM. The most reliable ECHO variables to identify AFF dogs were LVDs indexed to BW by allometric scaling and ESVI; one of the least reliable was sphericity index. Ventricular arrhythmias (VA) were identified in 13.6% of the population, with the highest prevalence in AFF deerhounds (42%).

CONCLUSIONS

Preclinical DCM in deerhounds is common and VA may be associated with DCM. Healthy deerhounds have higher LVDd, LVDs and EDVI compared with other breeds. This study provides ECHO RIs for deerhounds; sex or BW RIs should be used when screening.

ECHOCARDIOGRAPHIC PARAMETERS IN AFRICAN WHITE-BELLIED PANGOLINS (PHATAGINUS TRICUSPIS) WITHOUT CARDIAC DISEASE

Relatively little is known about pangolin care and physiology, and it has become increasingly important to have a better understanding of normal health parameters for evaluation of free-ranging, rehabilitating, and managed populations. Echocardiograms were performed on six African white-bellied pangolins (Phataginus tricuspis) under professional care at a single institution. Because of the propensity of pangolins to roll up with only thick keratinized scales exposed, the pangolins were anesthetized with either isoflurane or sevoflurane. All echocardiograms were performed and evaluated by a board-certified cardiologist. None of the pangolins had any evidence of prior cardiac disease. All standard measurements were obtained. Four pangolins (66.7%) had trace to mild mitral regurgitation, six (100%) had trace to mild tricuspid regurgitation, and two (33.3%) had trace to mild pulmonic regurgitation. All examinations were determined to be normal, with no evidence of valvular structural abnormalities, cardiac dysfunction, chamber enlargement, or cardiac hypertrophy. This report broadens understanding of normal echocardiogram parameters in pangolin species and contributes techniques and baseline data for veterinarians caring for these vulnerable populations.

ECHOCARDIOGRAPHIC PARAMETERS IN EIGHT ADULT TIGERS ( PANTHERA TIGRIS) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL

Eight adult tigers ( Panthera tigris) underwent a complete echocardiographic examination following sedation with medetomidine, midazolam, and induction of general anesthesia using ketamine and isoflurane (phase 1). Atipamezole was used to antagonize medetomidine (phase 2) and a second echocardiographic examination was performed. Physiologic tricuspid and pulmonic regurgitations were common findings in the sample population and one tiger was excluded from final analyses due to the finding of a ventricular septal defect. Measurements and mean arterial pressure were assessed for statistically significant differences between the two examination phases as well as gender and weight. There was a statistically significant difference between interventricular septum thickness at end systole, ejection fraction, and mean arterial pressure between anesthetic phases while fractional shortening and left ventricular internal dimension at end-systole approached, but did not reach, statistical significance between phases. Weight was found to be a statistically significant predictor of stroke volume and left ventricular internal dimension at end-diastole. The echocardiographic measurements obtained during this study can be used as guidelines for future examinations in adult tigers. The effects of medetomidine on these measurements and systolic function should be taken into account when performing echocardiograms and monitoring anesthetic events.

N-Terminal Pro-B-Type Natriuretic Peptide and Phonocardiography in Differentiating Innocent Cardiac Murmurs from Congenital Cardiac Anomalies in Asymptomatic Puppies

BACKGROUND

Differentiating innocent cardiac murmurs from murmurs caused by congenital cardiac anomalies can be challenging with auscultation alone in asymptomatic puppies.

HYPOTHESIS

Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations and phonocardiograms recorded by an electronic stethoscope can differentiate innocent from pathologic cardiac murmurs.

ANIMALS

A total of 186 client-owned asymptomatic dogs: 135 Cairn Terriers (age: 45-124 days), 20 adult Cairn Terriers (age: 7.5 months to 13.5 years), and 31 puppies of various breeds (age: 29-396 days).

METHODS

Study design is a cross-sectional survey. Each dog was auscultated, and when a cardiac murmur was heard, a phonocardiogram was recorded and an echocardiogram was performed. Plasma NT-proBNP concentrations were measured by a single laboratory by an ELISA.

RESULTS

No significant (P = .41) difference in plasma NT-proBNP levels was found between puppies without a murmur and puppies with an innocent murmur (median 300 versus 326 pmol/L), and between clinically healthy adult Cairn Terriers and Cairn Terrier puppies. Plasma NT-proBNP levels in puppies with a congenital heart disease were significantly (P < .001) higher than those in puppies with innocent murmurs (median 1,102 versus 326 pmol/L). However, some puppies with severe pulmonic stenosis did not have increased plasma NT-proBNP levels. On phonocardiograms, innocent murmurs had a significantly (P < .001) shorter "murmur-to-systole duration ratio" than the abnormal ones (median 66 versus 100%). The "murmur-to-S1 (first cardiac sound) amplitude ratio" was significantly (P < .001) lower of the innocent murmurs compared with that of the abnormal ones (median 16 versus 58 %).

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma NT-proBNP concentrations within the reference range do not rule out a congenital cardiac anomaly. Murmurs longer than 80% of the systole are most likely abnormal, whereas murmurs shorter than that could be either innocent or pathologic.

Echocardiographic diagnosis and necropsy findings of a congenital ventricular septal defect in a stranded harbor porpoise

A live-stranded harbor porpoise Phocoena phocoena was found on the west coast of the Dutch island Texel (North Sea) and transported to a rehabilitation center for small cetaceans, where it underwent a veterinary health check. Cardiac auscultation revealed a systolic cardiac murmur with the point of maximal intensity in the right hemithorax with an intensity of IV out of VI. Transthoracic echocardiography revealed a congenital ventricular septal defect with left-to-right shunting. Because the left atrium was not dilated according to the reference range of canine left atrium to aortic ratio, the presence of congestive heart failure was considered very unlikely. Therefore, this congenital cardiac anomaly was thought to be a clinically non-relevant incidental finding and would not explain the weakness, coughing, anorexia, vomiting, and diarrhea. Because the animal was still unable to swim or eat by itself after 2 wk of supportive care, it was euthanized. Post-mortem examination confirmed the presence of a ventricular septal defect. The weight of the heart relative to the animal's length was greater than expected, using linear regression analysis on the lengths and cardiac weights of 71 other stranded wild harbor porpoises without macroscopic cardiac pathologic changes. This finding suggests that the left ventricle had an eccentric hypertrophy because of volume overload resulting from the intracardiac shunt. This is the first report of a congenital cardiac anomaly and its ante-mortem diagnosis in this species. Data presented for the other 71 harbor porpoises may provide reference values for this species.

Innocent Cardiac Murmur in Puppies: Prevalence, Correlation with Hematocrit, and Auscultation Characteristics

BACKGROUND

The aims of this study were to establish the prevalence of innocent cardiac murmurs in clinically healthy puppies, to investigate a possible correlation between the presence of an innocent murmur and hematocrit, and to describe the auscultation characteristics of innocent murmurs.

HYPOTHESIS

Lower hematocrit contributes to the genesis of innocent murmurs.

ANIMALS

Five hundred and eighty-four client-owned clinically healthy puppies, between 20 and 108 days old.

METHODS

Two cross-sectional surveys with a 1-year (n = 389 pups) pilot and a half-year (n = 195 pups) principal study periods. Cardiac auscultation was performed by a single, board-certified cardiologist. Hematocrit was measured with an automatized hematology analyzer. Echocardiography was performed only on puppies with a cardiac murmur in the principal study.

RESULTS

In the pilot study, 15% of the dogs had a murmur. Innocent murmur was diagnosed in 28% of the 195 dogs in the principal study. Innocent murmurs were systolic, mostly with a musical character and with a maximal intensity of 2 of 6, and mostly with the point of maximal intensity in the left cardiac base. The hematocrit was significantly lower in the group with a murmur compared to the group without (P = .023).

CONCLUSIONS AND CLINICAL IMPORTANCE

Innocent murmur was a common finding in puppies at the age when the first veterinary controls usually take place. Physiologic anemia contributes to the genesis of innocent murmurs in puppies. Rising hematocrit in growing puppies can explain the spontaneous disappearance of innocent murmurs with aging. Hematocrit did not differentiate innocent murmurs from abnormal murmurs.

PREVALENCE OF VALVULAR REGURGITATIONS IN CLINICALLY HEALTHY CAPTIVE LEOPARDS AND CHEETAHS: A PROSPECTIVE STUDY FROM THE WILDLIFE CARDIOLOGY (WLC) GROUP (2008-2013)

The purpose of this prospective study was to evaluate transthoracic echocardiograms from clinically healthy large felids for the presence of valvular regurgitations (VR). Physiologic VR commonly occur in normal dogs and cats, but the percentage of large felids with VR has not been previously reported. During a 5-yr study period (2008-2013), 28 healthy animals were evaluated under general anesthesia: 16 cheetahs (Acinonyx jubatus soemmeringuii) with a mean age of 1.5±0.8 yr (range 0.7-3.5 yr), 5 Amur leopards (Panthera pardus orientalis), 1 snow leopard (Uncia uncia), and 6 clouded leopards (Neofelis nebulosa). For this study, all the leopards were gathered in one so-called "leopards group" with a mean age of 2.8±3.4 yr (range 0.3-10.7 yr). All valves observed in each view were examined for evidence of regurgitant jets and turbulent blood flow using the color-flow Doppler mode. Valves were also examined for structural changes. Mitral valve and aortic cusp abnormalities were considered to be of congenital origin. Mitral valve lesions led to mitral insufficiency in all the felids. Aortic cusp abnormalities led to aortic regurgitation in 94% of the cheetahs and 67% of the leopards. Leopards showed a predominance of early systolic mitral regurgitations, whereas all the mitral regurgitation jets in cheetahs were holosystolic. Tricuspid regurgitation was found in 81% of the cheetahs and in 50% of the leopards, whereas pulmonic regurgitation was detected in 44% of the cheetahs and 33% of the leopards. Interestingly, none of these tricuspid and pulmonic regurgitations were associated with two-dimensional structural valve abnormalities, thus suggesting their physiologic origin, as described in humans, cats, and dogs. In conclusion, subclinical valvular diseases are common in apparently healthy leopards and cheetahs. Longitudinal follow-up of affected animals is therefore required to assess their clinical outcome.

Cardiac evaluation of clinically healthy captive maned wolves (Chrysocyon brachyurus)

The objective of this project was to determine radiographic vertebral heart sizes and electrocardiographic (ECG) and echocardiographic measurements in healthy anesthetized maned wolves (Chrysocyon brachyurus). The wolves, housed at the White Oak Conservation and Smithsonian National Zoo Conservation and Research Centers, were being anesthetized for annual examinations. Cardiac auscultation, thoracic radiographs, a standard 6-lead ECG, and echocardiography were performed on the wolves while they were under general anesthesia. Thirteen maned wolves were evaluated: five males and eight females. Mean age was 6.4 +/- 4.4 years (range, 2-13 years). Mean weight was 26 +/- 2.95 kg (range, 22-32 kg). Low-grade systolic murmurs were auscultated in three of 13 maned wolves. Evaluation of ECGs revealed a sinus rhythm, with a QRS morphology, and mean electrical axis similar to domestic canines. Radiographic evaluation revealed a mean vertebral heart size of 8.27 +/- 0.48 (range, 7.9-8.6). In addition, the cardiac silhouette was seen to elongate, with an increase in sternal contact in older wolves. Echocardiography showed that mitral valve degenerative changes and insufficiency is likely common in older wolves. Visualization of physiologic regurgitation across the mitral and pulmonary valves was common in wolves of all ages. Left ventricular measurements were similar to those reported for healthy dogs, and several variables correlated well with body weight. Two wolves were found to have one to three heartworms in the right pulmonary artery, and degenerative mitral valve disease was determined in maned wolves older than 6 years of age. All of the wolves in this study were on heartworm preventative and tested negative for heartworm antigen at their annual examinations. The results of this study provide reference information for use in the cardiac evaluation of anesthetized maned wolves.

Doppler echocardiography–derived evidence of pulmonary arterial hypertension in dogs with degenerative mitral valve disease: 86 cases (2001–2005)

OBJECTIVE

To determine the prevalence of Doppler echocardiography-derived evidence of pulmonary arterial hypertension (DEE-PAH) in dogs with mitral valve disease (MVD) classified according to the International Small Animal Cardiac Health Council (ISACHC) heart failure classification scheme and various echocardiographic and Doppler indices of MVD severity.

DESIGN

Retrospective case series.

ANIMALS

617 dogs examined from 2001 to 2005 with MVD in ISACHC classes I to III.

PROCEDURES

Dogs were examined echocardiographically. Criteria used for systolic and diastolic DEE-PAH were detection of high tricuspid (> or = 2.5 m/s) and telediastolic pulmonic (> or = 2.0 m/s) valvular peak regurgitant jet velocities, respectively, by use of continuous-wave Doppler echocardiography.

RESULTS

86 (13.9%) dogs with MVD had a diagnosis of DEE-PAH. Severity and prevalence of DEE-PAH increased with ISACHC class (3.0%, 16.9%, 26.7%, and 72.2% prevalences for ISACHC classes Ia, Ib, II, and III, respectively). A significant correlation between systolic or diastolic pulmonary arterial pressure and left atrial-to-aortic diameter ratio (LA/Ao) was detected. Doppler echocardiography-derived evidence of pulmonary arterial hypertension was detected in 18 dogs with values of LA/Ao within reference range, all of which had moderate (n = 2 dogs) or severe (16) mitral valve regurgitation on color Doppler imaging.

CONCLUSIONS AND CLINICAL RELEVANCE

The prevalence and degree of DEE-PAH were related to the severity of MVD. Changes associated with DEEPAH may be detected in early stages of the disease, but only in dogs with severe mitral valve regurgitation.

TRANSESOPHAGEAL ECHOCARDIOGRAPHY OF THE LEFT VENTRICULAR OUTFLOW TRACT, AORTIC VALVE AND ASCENDING AORTA IN BOXER DOGS WITH HEART MURMURS

The study was aimed at evaluating the anatomy of the left ventricular outflow tract, aortic valve, and ascending aorta by means of multiplane transesophageal echocardiography in Boxer dogs with left basilar heart murmurs and at comparing two-dimensional (2D) transthoracic to transesophageal echocardiography for the diagnosis of subaortic stenosis in this breed. Twenty-eight Boxers were included in the study and allocated to four groups according to physical and routine transthoracic 2D and Doppler echocardiography findings: group A--dogs with low grade (I-II/VI) heart murmurs without overt evidence of aortic stenosis (14 dogs); group B--dogs with type 1 subaortic stenosis (seven dogs); group C--dogs with type 2 subaortic stenosis (five dogs); group D--dogs with type 3 subaortic stenosis (two dogs). Anatomic lesions were not discovered by transesophageal echocardiography in dogs belonging to group A. Transesophageal imaging confirmed the type of subaortic stenosis, as graded by transthoracic echocardiography, in diseased animals (groups BCD). Morphologic information obtained by transesophageal echocardiography in Boxer dogs was similar to that obtained by transthoracic echocardiography.

Tissue Doppler Imaging and Echo-Doppler Findings Associated with a Mitral Valve Stenosis with an Immobile Posterior Valve Leaflet in a Bull Terrier

A mitral valve stenosis was diagnosed in a 2-year-old female Bull Terrier by use of two-dimensional (2-D) and M-mode echocardiography, colour-flow imaging and spectral Doppler examinations. Tissue Doppler Imaging was also performed to assess the segmental radial myocardial motion. The mitral valve stenosis was characterized by a decreased mitral orifice area/left ventricle area ratio (0.14), an increased early diastolic flow velocity (E wave = 1.9 m/s), a prolonged pressure half-time (106 ms) and a decreased E-F slope (4.5 cm/s) on pulsed-wave Doppler examination. This mitral stenosis was associated with an immobile posterior leaflet, as seen on 2-D and M-mode echocardiography. Immobility of the posterior mitral leaflet is considered to be a rare finding in humans and, to our knowledge, has not been precisely documented in dogs with mitral valve stenosis.

Long-term follow-up of dogs with patent ductus arteriosus

Postocclusion survival data from dogs with left-to-right shunting patent ductus arteriosus (PDA) was available from 80 dogs, diagnosed from 1990 to 2000. Of these, 37 had undergone a procedure to close the ductus and were re-evaluated at the time of this study; clinical data from the follow-up examination was compared with that from the original examination. Radiographically, the right ventricle remained apparently enlarged, and the aortic bulge associated with dilation of the descending aorta did not disappear after closure. On M-mode echocardiography, left ventricular chamber diameter in diastole and systole and left ventricular posterior wall in systole decreased significantly. Mitral endocardiosis was a common feature. Residual flow was evident in 46 per cent of the animals. Late closure occurred in 8 per cent of the dogs, and trivial recanalisation in 19 per cent. The maximum survival time postclosure was 168 months and, after non-occlusion, 114 months, suggesting that dogs with PDA follow an unpredictable course. However, there was a significant difference in survival times between the corrected and non-corrected group.

Echocardiographic parameters in 14 healthy English Bull Terriers

OBJECTIVE

To determine the range of various cardiac parameters using echocardiography in apparently normal, healthy English Bull Terriers.

DESIGN

Fourteen English Bull Terriers were selected for study. Cardiac auscultation of the parents of these dogs was normal. Echocardiographic examination of one parent of each animal showed: no mitral or aortic valve abnormalities; no myocardial lesions; no two dimensional evidence of fixed or dynamic left ventricular outflow tract obstruction; and no systolic aortic or left ventricular outflow tract turbulence on colour flow Doppler examination. The 14 selected dogs did not have arrhythmias or murmurs, and on echocardiographic examination had similar findings to their parents. Systolic blood pressure was measured in all dogs and they had no clinical evidence of Bull Terrier polycystic kidney disease or Bull Terrier hereditary nephritis.

PROCEDURE

All dogs were auscultated and subjected to a sequential global echocardiographic assessment of the heart, including two dimensional long and short axis, and colour flow Doppler interrogation of the mitral and aortic valves. Dimensional measurements, including those from the left atrium, aortic annulus and left ventricle, were taken from a right parasternal window, and derived values such as fractional shortening, stroke volume and left atrial to aortic annulus ratio were calculated. Peak systolic aortic velocity was measured from the left parasternal window using two dimensional-guided pulsed wave Doppler with angle correction. Systolic blood pressure was measured using a Doppler monitor. The absence of Bull Terrier polycystic kidney disease was determined using renal ultrasonography, and of Bull Terrier hereditary nephritis using urinary protein to creatinine ratio.

RESULTS

These 14 dogs had greater left ventricular wall thickness and smaller aortic root diameters than those reported as normal for other breeds of comparable body size. Left atrial dimensions were also larger, however this may have been due to the "maximising" method of measurement. These apparently normal English Bull Terriers also had higher aortic velocities than those reported for other breeds, possibly due to a smaller aortic root diameter or other anatomic substrate of the left ventricular outflow tract, lower systemic vascular resistance, or breed-specific "normal" left ventricular hypertrophy. While these dogs were selected to be as close to normal as possible, the breed may have a particular anatomy that produces abnormal left ventricular echocardiographic parameters.

CONCLUSION

These echocardiographic parameters may be used to diagnose left ventricular outflow tract obstruction and left ventricular hypertrophy, and inaccurate diagnoses may result if breed-specific values are not used.

Aortic ejection velocity in healthy Boxers with soft cardiac murmurs and Boxers without cardiac murmurs: 201 cases (1997-2001)

OBJECTIVE

To determine aortic ejection velocity in healthy adult Boxers with soft ejection murmurs without overt structural evidence of left ventricular outflow tract obstruction and in healthy Boxers without cardiac murmurs.

DESIGN

Retrospective study.

ANIMALS

201 Boxers.

PROCEDURE

Dogs were examined independently by 2 individuals for evidence of a cardiac murmur, and a murmur grade was assigned. Maximal instantaneous (peak) aortic ejection velocity was measured by means of continuous-wave Doppler echocardiography from a subcostal location. Forty-eight dogs were reexamined approximately 1 year later.

RESULTS

A soft (grade 1, 2, or 3) left-basilar ejection murmur was detected in 113 (56%) dogs. Overall median aortic ejection velocity was 1.91 m/s (range, 1.31 to 4.02 m/s). Dogs with murmurs had significantly higher aortic ejection velocities than did those without murmurs (median, 2.11 and 1.72 m/s, respectively). Auscultation of a murmur was 87% sensitive and 66% specific for the identification of aortic ejection velocity > 2.0 m/s. An ejection murmur and aortic ejection velocity > 2.0 m/s were identified in 73 (36%) dogs. For most dogs, observed changes in murmur grade and aortic ejection velocity during a follow-up examination 1 year later were not clinically important.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that ejection murmurs were common among healthy adult Boxers and that Boxers with murmurs were likely to have high (> 2.0 m/s) aortic ejection velocities. The cause of the murmurs in these dogs is unknown.