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Objective

To describe the historical, clinical, and echocardiographic findings in Dalmatians with dilated cardiomyopathy (DCM).

Design

Retrospective case series.

Sample Population

9 Dalmatians with a diagnosis of DCM and congestive heart failure (CHF), 9 Doberman Pinschers with DCM and CHF, and 9 dogs of other breeds with DCM and CHF.

Procedure

Disease history; signalment; physical, radiographic, and echocardiographic examination findings; treatment; and outcome from medical records were analyzed.

Results

All Dalmatians were male, with a mean age of 6.8 years. Eight dogs had been fed a commercially available low-protein diet formulated for the prevention of urate uroliths. All dogs had clinical signs consistent with left-sided CHF and had marked left ventricular systolic dysfunction and severe left ventricular dilatation, although arrhythmias were not an important finding in this series of dogs. Median duration of survival was 10 months.

Clinical Implications

The DCM syndrome in Dalmatians has some qualities that are distinct from DCM in other breeds of dogs. (J Am Vet Med Assoc 1996;209:1592–1596)

Free access
in Journal of the American Veterinary Medical Association

Objective

To investigate development of femoral artery occlusion in Cavalier King Charles Spaniels.

Design

Prospective study.

Animals

954 Cavalier King Charles Spaniels.

Procedure

1,750 cardiovascular examinations consisting of visual inspection of mucous membranes, thoracic auscultation in areas associated with the heart valves, thoracic palpation, and palpation of the femoral arteries were made at 10 dog shows on 954 dogs. Findings of clinically normal, weak, or undetectable femoral pulses were recorded. Pathologic changes in occluded femoral arteries of 2 dogs were examined histologically.

Results

Of the 954 dogs, 22 (2.3%) had an undetectable right or left femoral pulse on 1 or more examinations. Forty (4.2%) additional dogs had weak unilateral or bilateral femoral pulses. Only 1 dog had exercise intolerance, and it had coexistent congestive heart failure. Histologic examination of serial sections of an occluded femoral artery from 1 dog revealed intimai thickening with breaks in the internal elastic lamina proximal to the occluded segment. The occluded segment of the femoral artery was contracted and filled with an organizing, recanalizing thrombus. Similar histopathologic changes were found in sections of a femoral artery from another dog.

Clinical Implications

Femoral artery occlusion is rare in other breeds and is not clinically important in dogs because of adequate collateral circulation; however, its rather common development in Cavalier King Charles Spaniels indicates a genetic predisposition and probable weakness in the femoral artery wall. (J Am Vet Med Assoc 1997;211:872–874)

Free access
in Journal of the American Veterinary Medical Association

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

Abstract

Objective—To quantify myocardial contrast enhancement (MCE) of the left ventricle (LV) by use of cardiac magnetic resonance imaging (CMRI) in healthy cats and cats with hypertrophic cardiomyopathy (HCM) and to compare MCE between the 2 groups.

Animals—10 healthy cats and 26 Maine Coon cats with moderate to severe HCM but without clinical evidence of congestive heart failure.

Procedure—Anesthetized cats underwent gradient echo CMRI examination. Short-axis images of the LV were acquired before and 7 minutes after IV administration of gadolinium dimeglumine. Regions of interest were manually traced in the quadrants of 5 mid-LV slices acquired at end systole, and the MCE percentage was calculated from summed weight-averaged data from all slices. Doppler tissue imaging echocardiography was performed to measure the early diastolic myocardial velocity (Em) as an index of diastolic function. Three-way repeated-measures ANOVA was used to determine differences in MCE between cats with HCM and healthy cats. Simple linear regression was used to assess whether MCE was correlated with LV mass, LV mass index (LVMI), or Em. A Student t test was used to compare the SDs of the postcontrast myocardial signal intensity between the 2 groups.

Results—There was no difference in MCE between cats with HCM and healthy cats. There was no correlation of MCE with LV mass, LVMI, or Em. There was no difference in heterogeneity of signal intensities of LV myocardium between the 2 groups.

Conclusions and Clinical Relevance—Contrastenhancement CMRI was not useful in detecting diffuse myocardial fibrosis in cats with HCM. (Am J Vet Res 2005;66:1891–1894)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the hemodynamic effects of orally administered carvedilol in healthy dogs with doses that might be used to initiate treatment in dogs with congestive heart failure.

Animals—24 healthy dogs.

Procedure—Dogs were randomly allocated to receive carvedilol PO at a dose of 1.56, 3.125, or 12.5 mg, twice daily for 7 to 10 days; 6 dogs served as controls. Investigators were blinded to group assignment. Hemodynamic variables were recorded prior to administration of the drug on day 1 and then 2, 4, and 6 hours after the morning dose on day 1 and days 7 to 10. Change in heart rate after IV administration of 1 µg of isoproterenol/kg and change in systemic arterial blood pressure after IV administration of 8 µg of phenylephrine/kg were recorded 2 and 6 hours after administration of carvedilol.

Results—Administration of carvedilol did not significantly affect resting hemodynamic variables or response to phenylephrine. The interaction of day and carvedilol dose had a significant effect on resting heart rate, but a significant main effect of carvedilol dose on resting heart rate was not detected. Increasing carvedilol dose resulted in a significant linear decrease in heart rate response to isoproterenol.

Conclusions and Clinical Relevance—In healthy conscious dogs, orally administered carvedilol at mean doses from 0.08 to 0.54 mg/kg given twice daily did not affect resting hemodynamics. Over the dose range evaluated, there was a dose-dependent attenuation of the response to isoproterenol, which provided evidence of β-adrenergic receptor antagonism. (Am J Vet Res 2005;66:637–641)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the feasibility for use of a 6- minute walk test (6-MWT) in dogs with congestive heart failure (CHF) and document that the distance walked in 6 minutes decreases when a dog has CHF.

Animals—16 young mature male hound-crossbred dogs weighing between 25 and 37 kg.

Procedure—An unobstructed path (22.73 m) was measured in a hallway. Each dog was walked on a leash for 6 minutes; each dog was allowed to set its own pace. At the end of 6 minutes (as measured by use of a stopwatch), the total distance walked was measured. Heart rate (HR) obtained by auscultation and mean systemic arterial pressure (MAP) obtained by oscillometry were recorded before and after the 6- MWT. Heart failure was induced by use of rapid ventricular pacing. Mean of the distance walked, HR, and MAP before and after the 6-MWT were compared between the control period and after dogs developed induced CHF.

Results—Dogs with CHF had a significant increase in resting HR, significant decrease in MAP, and a significant decrease in the distance walked in 6 minutes. The MAP increased slightly after exercise during the control period but decreased slightly after exercise during the CHF period. Fractional shortening decreased significantly when dogs had CHF.

Conclusions and Clinical Relevance—Analysis of these results indicated that the distance walked in 6 minutes decreased significantly when a dog had CHF. The 6-MWT requires little time, space, or equipment and may replace the treadmill exercise test. ( Am J Vet Res 2004;65:311–313)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate plasma concentrations and urinary excretion of vasopressin and cortisol and urinary excretion of catecholamines in dogs with dilated cardiomyopathy (DCM).

Animals—15 dogs with clinical signs of DCM, 15 dogs with preclinical DCM, and 15 control dogs.

Procedure—Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs. Blood and urine samples were collected.

Results—Plasma concentration of vasopressin and the urine cortisol-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM and dogs with preclinical DCM, compared with control dogs. Plasma vasopressin concentration was significantly higher in dogs with clinical signs of DCM, compared with dogs with preclinical DCM. Urine vasopressin-to-urine creatinine ratio was significantly increased in dogs with clinical signs of DCM, compared with dogs with preclinical DCM and control dogs. Urine epinephrine-to-urine creatinine ratio and urine norepinephrine-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM, compared with control dogs. Plasma concentration of cortisol and urine dopamine-to-urine creatinine ratio did not differ significantly among groups.

Conclusions and Clinical Relevance—According to this study, the neuroendocrine pattern is changed in dogs with preclinical DCM. These changes are even more pronounced in dogs with clinical signs of DCM. Analysis of concentrations of vasopressin, cortisol, and catecholamines may aid in identification of the clinical stages of DCM. These findings may also provide a basis for additional studies of the possible beneficial effects of vasopressin antagonists and β-adrenergic receptor antagonists in the treatment of dogs with congestive heart failure and DCM. (Am J Vet Res 2005;66:1709–1717)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine current population characteristics of, clinical findings in, and survival times for cats with hypertrophic cardiomyopathy (HCM).

Design—Retrospective study.

Animals—260 cats with HCM.

Procedure—Information was obtained from the medical records. Cats were classified into 1 of 4 clinical groups (congestive heart failure [CHF] group, arterial thromboembolism [ATE] group, syncope group, or cats without clinical signs [subclinical group]) on the basis of the primary clinical signs at the initial examination.

Results—120 cats were classified in the CHF group, 43 in the ATE group, 10 in the syncope group, and 87 in the subclinical group. Antecedent events that may have precipitated CHF included IV fluid administration, anesthesia, surgery, and recent corticosteroid administration. Median survival time was 709 days (range, 2 to 4,418 days) for cats that survived > 24 hours. Cats in the subclinical group lived the longest (median survival time, 1,129 days; range, 2 to 3,778 days), followed by cats in the syncope group (654 days; range, 28 to 1,505 days), cats in the CHF group (563 days; range, 2 to 4,418 days), and cats in the ATE group (184 days; range, 2 to 2,278 days). Causes of death included ATE (n = 56), CHF (49), sudden death (13), and noncardiac causes (27). In univariate analyses, survival time was negatively correlated with left atrial size, age, right ventricular enlargement, and thoracentesis. Cats with systolic anterior motion of the mitral valve lived longer than cats without this echocardiographic finding. In multivariate analyses, only age and left atrial size remained significant predictors of survival time.

Conclusions and Clinical Relevance—Although overall survival time for cats with HCM was similar to earlier reports, survival times for cats with CHF or ATE were longer than previously reported. (J Am Vet Med Assoc 2002;220:202–207)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe surgical techniques for and assess outcome of treatment of mitral regurgitation in dogs.

Design—Uncontrolled prospective study.

Animals—18 dogs with naturally occurring mitral regurgitation.

Procedure—All dogs weighed > 5 kg (11 lb) and had severe mitral regurgitation, congestive heart failure (CHF), and no serious noncardiac disease. Left ventricular volume indices, left atrial size, and degree of mitral regurgitation were determined echocardiographically before and after surgery. Repair techniques included circumferential annuloplasty, placement of artificial chordae, chordal fenestration and papillary muscle splitting, and edge-to-edge repair. Factors predictive for surgery survival and resolution of CHF were determined.

Results—12 dogs survived surgery. Factors predictive for surgery survival included weight > 10 kg (22 lb) and CHF of less than 6 months' duration. In 9 dogs, CHF resolved for a median period of 1 year (range, 4 months to 3 years) after surgery. One dog had stable CHF at 12 months. One dog died as a result of progressive CHF; another was euthanatized for a noncardiac reason. Left ventricular diastolic volume index was 226.9 ± 117.7 cm3/m2 before surgery and 134.9 ± 70.4 cm3/m2 at 6 months after surgery (n = 10). Factors predictive for resolution of CHF included left ventricular diastolic volume index < 250 cm3/m2 and systolic volume index < 70 cm3/m2.

Conclusion and Clinical Relevance—Mitral valve repair may resolve CHF in dogs with severe mitral regurgitation, particularly in dogs that weigh > 10 kg and are treated within 6 months of the onset of CHF. (J Am Vet Med Assoc 2004;224:1941–1945)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify clinical, echocardiographic, and electrocardiographic abnormalities in Boxers with cardiomyopathy and echocardiographic evidence of left ventricular systolic dysfunction.

Design—Retrospective study.

Animals—48 mature Boxers.

Procedure—Medical records were reviewed for information on age; sex; physical examination findings; and results of electrocardiography, 24-hour ambulatory electrocardiography, thoracic radiography, and echocardiography.

Results—Mean age of the dogs was 6 years (range, 1 to 11 years). Twenty (42%) dogs had a systolic murmur, and 9 (19%) had ascites. Congestive heart failure was diagnosed in 24 (50%) dogs. Seventeen (35%) dogs had a history of syncope. Mean fractional shortening was 14.4% (range, 1% to 23%). Mean left ventricular systolic and diastolic diameters were 4.5 cm (range, 3 to 6.3 cm) and 5.3 cm (range, 3.9 to 7.4 cm), respectively. Twenty-eight (58%) dogs had a sinus rhythm with ventricular premature complexes (VPCs), and 20 had supraventricular arrhythmias (15 with atrial fibrillation and 5 with sinus rhythm and atrial premature complexes). Sixteen of the dogs with supraventricular arrhythmias also had occasional VPCs. Morphology of the VPCs seen on lead II ECGs was consistent with left bundle branch block in 25 dogs, right bundle branch block in 8, and both in 11.

Conclusions and Clinical Relevance—Results suggest that Boxers with cardiomyopathy and left ventricular dysfunction frequently have arrhythmias of supraventricular or ventricular origin. Whether ventricular dysfunction was preceded by electrical disturbances could not be determined from these data, and the natural history of myocardial disease in Boxers requires further study. (J Am Vet Med Assoc 2005;226:1102–1104)

Full access
in Journal of the American Veterinary Medical Association