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

Abstract

BackgroundThe 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.HypothesisLower hematocrit contributes to the genesis of innocent murmurs.AnimalsFive hundred and eighty‐four client‐owned clinically healthy puppies, between 20 and 108 days old.MethodsTwo 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.ResultsIn 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 ImportanceInnocent 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.

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

“…If a murmur was detected, the following variables were noted: point of maximal intensity, intensity (scale 1–6), timing (systolic, diastolic, or continuous), and additional characteristics, such as musical character and beat‐to‐beat variability in murmur intensity . A murmur was defined as intermittent, if a soft (1 or 2 of 6) murmur was heard, which disappeared whereas the auscultation was still performed on the same location, or when the murmur was not audible on each heartbeat …”

“…Detecting a cardiac murmur in clinically healthy puppies during the first veterinary health check is common . Innocent murmurs (also known as functional, physiologic, or flow murmurs) in puppies can be caused by low viscosity of blood as a result of low hematocrit . This anemia is physiologic in young dogs and it resolves together with the innocent murmurs with maturation .…”

“…Innocent murmurs (also known as functional, physiologic, or flow murmurs) in puppies can be caused by low viscosity of blood as a result of low hematocrit . This anemia is physiologic in young dogs and it resolves together with the innocent murmurs with maturation . To determine whether a murmur is innocent or pathologic can be challenging based on cardiac auscultation alone in first‐opinion veterinary practices .…”

“…This anemia is physiologic in young dogs and it resolves together with the innocent murmurs with maturation . To determine whether a murmur is innocent or pathologic can be challenging based on cardiac auscultation alone in first‐opinion veterinary practices . This decision is, however, of major importance, as a pup with a pathologic murmur should ideally be referred to a veterinary cardiologist, whereas innocent murmurs require no further veterinary attention .…”

“…To determine whether a murmur is innocent or pathologic can be challenging based on cardiac auscultation alone in first‐opinion veterinary practices . This decision is, however, of major importance, as a pup with a pathologic murmur should ideally be referred to a veterinary cardiologist, whereas innocent murmurs require no further veterinary attention . First‐line veterinary practitioners lack a simple, in‐house diagnostic test that can facilitate differentiating innocent cardiac murmurs from murmurs caused by congenital cardiac anomalies.…”