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Objective

To study the relationship between parental cardiac status in Cavalier King Charles Spaniels and development of chronic valvular disease (CVD) in offspring.

Design

Historical cohort.

Animals

54 female and 53 male Cavalier King Charles Spaniel offspring.

Procedure

7 sires, selected on the basis of their liability to develop CVD, were screened for clinical signs of CVD and assigned to 1 of 3 groups (late, intermediate, and early onset of CVD). The mates of these sires (30 dams) were selected and classified likewise, and 107 offspring produced in 1988 from matings between these parents were screened for clinical signs of CVD at a mean age of 5.3 ± 0.3 years.

Results

55% of the offspring were free from clinical signs of CVD, whereas 45% had cardiac murmurs of low or moderate intensity. The proportion of offspring with heart murmurs and the intensity of murmurs were significantly greater with increased parental classification. More males than females had developed murmurs, and murmurs of moderate intensity also were more prevalent in males. Results of multiple-regression analysis indicated that mean parental classification and sex had significant effects on proportion of offspring with murmurs and their intensity. Additionally, age affected disease prevalence and severity, despite the narrow range in age of offspring examined.

Clinical Implications

Parental CVD status is an important factor influencing the probability of heart murmurs and their intensity in offspring. The results of this study indicate that CVD development is a polygenic threshold trait and that sex of the offspring influences threshold levels. (J Am Vet Med Assoc 1996;208:2009-2012)

Free access
in Journal of the American Veterinary Medical Association

Summary

Plasma concentration of immunoreactive atrial natriuretic peptide (ir-anp) was investigated in 83 Cavalier King Charles Spaniels with variable severity of mitral regurgitation caused by chronic valvular disease (cvd). Severity of mitral incompetence was assessed by echocardiography. Significant differences in plasma concentrations of ir-anp were not found between clinically normal dogs (New York Heart Association functional class O), dogs with only cardiac murmur (class I), and dogs with echocardiographic evidence of slight to moderate left atrial and ventricular dilatation (class II). Dogs with severe left atrial and ventricular dilatation and clinical signs of congestion (classes III and IV) were found to have significantly (P < 0.001) increased plasma concentration of ir-anp. Overall, moderate degree of association was found between plasma concentration of ir-anp and left atrial and left ventricular diameters (Pearson's r = 0.65, 0.60, respectively, P < 0.001), as well as heart rate (r = 0.47, P < 0.01). However, left atrial enlargement was found to have the predominant effect on plasma ir-anp concentration. It is concluded that the plasma concentration of ir-anp did not become markedly increased before decompensation of chronic mitral regurgitation associated with severe enlargement of the left atrium and ventricle in Cavalier King Charles Spaniels.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To investigate whether plasma activity of matrix metalloproteinase (MMP)-2 and -9 was associated with severity of myxomatous mitral valve disease (MMVD) in dogs and to assess potential associations between MMP activity and dog characteristics, echocardiographic variables, systolic arterial blood pressure (SAP), heart rate, cardiac troponin I (cTnI) concentration, and C-reactive protein concentration.

Animals—75 client-owned dogs.

Procedures—Severity of MMVD was assessed by use of echocardiography. Plasma activity of latent (pro-MMP) and active MMP-2 and -9 was analyzed via zymography. Plasma concentration of cTnI was analyzed with a high-sensitivity cTnI assay, and C-reactive protein concentration was analyzed with a canine-specific ELISA.

Results—Pro-MMP-9, active MMP-9, and pro-MMP-2 were detected, but active MMP-2 was not. No significant differences were found in MMP concentrations among the 4 MMVD severity groups. Activity of pro-MMP-9 decreased with decreases in SAP and was higher in male dogs than in female dogs. Activity of MMP-9 decreased with increases in left ventricular end-systolic dimension and with decreases in SAP and cTnI concentration. Left ventricular end-systolic dimension was the variable most strongly associated with MMP-9 activity. No associations were found between the activity of pro-MMP-2 and investigated variables.

Conclusions and Clinical Relevance—Plasma MMP-9 activity decreased with increases in the end-systolic left ventricular internal dimension and decreases in SAP. Hence, evaluation of MMP-9 activity has the potential to provide unique information about the myocardial remodeling process in dogs with MMVD.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate use of signal analysis of heart sounds and murmurs in assessing severity of mitral valve regurgitation (mitral regurgitation [MR]) in dogs with myxomatous mitral valve disease (MMVD).

Animals—77 client-owned dogs.

Procedures—Cardiac sounds were recorded from dogs evaluated by use of auscultatory and echocardiographic classification systems. Signal analysis techniques were developed to extract 7 sound variables (first frequency peak, murmur energy ratio, murmur duration > 200 Hz, sample entropy and first minimum of the auto mutual information function of the murmurs, and energy ratios of the first heart sound [S1] and second heart sound [S2]).

Results—Significant associations were detected between severity of MR and all sound variables, except the energy ratio of S1. An increase in severity of MR resulted in greater contribution of higher frequencies, increased signal irregularity, and decreased energy ratio of S2. The optimal combination of variables for distinguishing dogs with high-intensity murmurs from other dogs was energy ratio of S2 and murmur duration > 200 Hz (sensitivity, 79%; specificity, 71%) by use of the auscultatory classification. By use of the echocardiographic classification, corresponding variables were auto mutual information, first frequency peak, and energy ratio of S2 (sensitivity, 88%; specificity, 82%).

Conclusions and Clinical Relevance—Most of the investigated sound variables were significantly associated with severity of MR, which indicated a powerful diagnostic potential for monitoring MMVD. Signal analysis techniques could be valuable for clinicians when performing risk assessment or determining whether special care and more extensive examinations are required.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate whether time-frequency and complexity analyses of heart murmurs can be used to differentiate physiologic murmurs from murmurs caused by aortic stenosis (AS) in Boxers.

Animals—27 Boxers with murmurs.

Procedures—Dogs were evaluated via auscultation and echocardiography. Analyses of time-frequency properties (TFPs; ie, maximal murmur frequency and duration of murmur frequency > 200 Hz) and correlation dimension (T2) of murmurs were performed on phonocardiographic sound data. Time-frequency property and T2 analyses of low-intensity murmurs in 16 dogs without AS were performed at 7 weeks and 12 months of age. Additionally, TFP and T2 analyses were performed on data obtained from 11 adult AS-affected dogs with murmurs.

Results—In dogs with low-intensity murmurs, TFP or T2 values at 7 weeks and 12 months did not differ significantly. For differentiation of physiologic murmurs from murmurs caused by mild AS, duration of murmur frequency > 200 Hz was useful and the combination assessment of duration of frequency > 200 Hz and T2 of the murmur had a sensitivity of 94% and a specificity of 82%. Maximal murmur frequency did not differentiate dogs with AS from those without AS.

Conclusions and Clinical Relevance—Results suggested that assessment of the duration of murmur frequency > 200 Hz can be used to distinguish physiologic heart murmurs from murmurs caused by mild AS in Boxers. Combination of this analysis with T2 analysis may be a useful complementary method for diagnostic assessment of cardiovascular function in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To investigate activity of the renin-angiotensin-aldosterone system and N-terminal pro-atrial natriuretic peptide (NT-proANP) during development of clinical signs of decompensated mitral valve regurgitation (MR).

Animals

11 Cavalier King Charles Spaniels with advanced MR attributable to chronic valvular disease.

Procedure

Dogs were subjected to repeated examinations at 6-month intervals until signs of decompensation had developed (end point). Data acquired at end point were compared with data obtained from examinations 1 year and 1 to 6 months before decompensation. Each examination included physical examination, collection of venous blood, thoracic radiography, and echocardiography.

Results

Echocardiography measurements of left atrial-to-aortic root ratio and left ventricular end diastolic diameter increased considerably during the study, whereas left ventricular end systolic diameter remained unchanged. The increase in cardiac size was associated with increased plasma concentration of NT-proANP. In contrast, plasma concentrations of aldosterone and angiotensin II were reduced at decompensation (aldosterone compared with the 2 earlier examinations and angiotensin II compared with values obtained 1 to 6 months before), despite decreased plasma protein concentration and hematocrit, suggesting fluid retention. The urine-to-plasma creatinine ratio was reduced at end point.

Conclusion and Clinical Implications

Early decompensated MR in dogs was not associated with increased circulating renin-angiotensin-aldosterone system activity, which may be caused by increased activity of ANP, and may be important for future therapeutic strategies of MR. (Am J Vet Res 1997;58:77–82)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To study long-term effects of enalapril, an angiotensin-converting enzyme inhibitor, and hydralazine, an arteriodilator, on renin-angiotensin-aldosterone system and fluid balance before and after administration of furosemide.

Animals

22 dogs with clinical signs of congestive heart failure (CHF) attributable to mitral regurgitation.

Procedure

After initial examination, 12 dogs received enalapril and 10 received hydralazine. Dogs were re-examined 3 weeks and 6 months after initial examination. Furosemide was added after the 3-week examination, and at 6 months, dogs had received furosemide for at least 4 months.

Results

Angiotensin II and aldosterone plasma concentrations were low before treatment, and only aldosterone became significantly decreased after enalapril monotherapy. Concentrations of both hormones and heart rate increased in dogs receiving hydralazine monotherapy, and fluid retention was evident. After long-term treatment with either of the 2 drugs together with furosemide, angiotensin II and aldosterone values increased in both groups. Natriuresis and kaliuresis developed in all dogs, with greatest effect in those receiving enalapril and furosemide. These dogs had decreased plasma sodium concentration, whereas potassium concentration was equally decreased in both groups. After 6 months, the enalapril group, but not the hydralazine group, had increased cardiac size. All dogs had moderate reduction of weight and were azotemic, although changes were more pronounced in those of the hydralazine group.

Conclusion

The 2 drugs have different effects on the renin-angiotensin-aldosterone system and fluid balance in dogs with CHF. (Am J Vet Res 1996;57:1645–1652)

Free access
in American Journal of Veterinary Research