Clinical, echocardiographic, and electrocardiographic abnormalities in Boxers with cardiomyopathy and left ventricular systolic dysfunction: 48 cases (1985–2003)

Ryan D. BaumwartDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

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Kathryn M. MeursDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

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Clarke E. AtkinsDepartment of Companion Animal and Special Species, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.

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John D. BonaguraDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

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Teresa C. DeFrancescoDepartment of Companion Animal and Special Species, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.

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Bruce W. KeeneDepartment of Companion Animal and Special Species, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.

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Shianne KoplitzDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

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Virginia Luis FuentesDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

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Matthew W. MillerMichael E. DeBakey Institute, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843.

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William RauschDepartment of Companion Animal and Special Species, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.

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Alan W. SpierDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.
present address is the Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

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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)

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)