Use of Auscultation and Doppler Echocardiography in Boxer Puppies to Predict Development of Subaortic or Pulmonary Stenosis

Abstract

Background: Boxers are predisposed to subaortic and pulmonic stenosis (SAS, PS). Screening of puppies may be useful in estimating the risk of their developing a defect that potentially compromises life expectancy or exercise tolerance.Hypothesis: Presence of SAS or PS in adult Boxers can be predicted by auscultation and Doppler echocardiography at 9-10 weeks of age.Animals: Eighty-five Boxer puppies examined at 9-10 weeks of age and at 12 months of age. Methods: Prospective, longitudinal observational study. Auscultation by stethoscope and continuous wave-Doppler echocardiography for peak velocities (V max ) in the aorta (Ao) and pulmonary artery (PA).Results: Intensity of heart murmurs in puppies correlated with V max Ao and V max PA in adults. V max Ao and V max PA in puppies correlated with V max Ao and V max PA in adults, respectively. From puppy to adult, V max Ao increased and V max PA remained unchanged. The negative predictive value for absent or only a soft ( II/VI) murmur in puppies being associated with V max Ao and PA 2.4 m/s as an adult was 90% and 3.5 m/s 100%. The negative predictive value of a V max 2.4 m/s as a puppy still being 2.4 m/s as an adult was 94% for Ao and 96% for PA, and of a V max 3.5 m/s, 99% for Ao and 100% for PA.Conclusions and Clinical Importance: Even though V max Ao increases during growth in Boxer puppies, indicating relative narrowing of the aorta, puppies with V max Ao 2.4 m/s do not usually progress to clinically have relevant SAS at 12 months of age.

A prospective study of systolic ejection murmurs and left ventricular outflow tract in boxers

“…Neither the aortic, nor the pulmonic, flow velocity changed significantly in this study contrary to recent findings by Jenni and others (2009), who report increasing aortic flow velocity during growth in boxers. A possible explanation is the larger number of dogs in that study, but also the inclusion of dogs both with and without AS.…”

The relevance of echocardiography heart measures for breeding against the risk of subaortic and pulmonic stenosis in Boxer dogs1

“…Low intensity murmurs, quite common in puppies, are considered trivial functional murmurs that tend to disappear with aging. The same murmurs in adult dogs may be physiological and associated with athletic heart, high sympathetic tone, and anatomic factors, or in high risk breeds such as the Boxer dog, may be suggestiye of slight stenosis (Kvart et al, 1998;Koplitz et al, 2003;Jenni et al, 2009). Physiological and mild SubAS-linked murmurs are not always easily and accurately distinguishable by auscultation (Kvart et al, 1998).…”

Comparison of peak flow velocity through the left ventricular outflow tract and effective orifice area indexed to body surface area in Golden Retriever puppies to predict development of subaortic stenosis in adult dogs

“…However, in Boxers, both unaffected and affected dogs have significantly higher LVOT Vmax as adults, and a breed-specific characteristic has been suspected. 7 In the present study of Golden Retrievers, there was a significant increase in LVOT Vmax from baseline to follow-up in both unaffected dogs (P < 0.001) and dogs that met the criteria for SAS (P = 0.04). Possible explanations include physiologic cardiac remodeling in growing patients with underlying changes in heart volume-to-mass ratio, effect of growth hormone impregnation on contractile proteins and myocyte hypertrophy, and changes in cardiac cell populations with the critical role of cardiac fibroblast cells in heart growth.…”

“…Second, there is no widely accepted consensus on what should be accepted as the upper limit of Doppler-derived LVOT Vmax in the evaluation of dogs for SAS. Acceptance of breed-specific limits 7,24,33,39 is probably necessary and, even so, likely incomplete. We set the LVOT Vmax at 2.3 m/s as recommended by the European Society of Veterinary Cardiology.…”