• Open Access

Decreased Systolic Function and Inadequate Hypertrophy in Large and Small Breed Dogs with Chronic Mitral Valve Insufficiency

Authors

  • Michele Borgarelli,

    Corresponding author
    1. Department Patologia Animale, Faculty Veterinary Medicine, Via L. da Vinci 44, 10095, Grugliasco, Italy
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  • Alberto Tarducci,

    1. Department Patologia Animale, Faculty Veterinary Medicine, Via L. da Vinci 44, 10095, Grugliasco, Italy
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  • Renato Zanatta,

    1. Department Patologia Animale, Faculty Veterinary Medicine, Via L. da Vinci 44, 10095, Grugliasco, Italy
    2. Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Uppsala, Sweden
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  • Jens Haggstrom

    1. Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Uppsala, Sweden
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  • Preliminary results were presented at the European College Veterinary Internal Medicine—Companion Animal, Glasgow, 2005.

Department Patologia Animale, Faculty Veterinary, Medicine, Via L. da Vinci 44, 10095 Grugliasco, Italy; e-mail: michele.borgarelli@unito.it.

Abstract

Background: Systolic dysfunction associated with chronic mitral valve insufficiency (CMVI) has been demonstrated in experimental animal models and large breed (LB) dogs but has been reported as an uncommon finding in small breed (SB) dogs with naturally occurring disease. It has been suggested the myocardial failure could be, in part, because of an insufficient increase in left ventricular mass.

Hypothesis: To test if SB and LB dogs with CMVI and moderate heart failure have systolic dysfunction and if they have adequate eccentric hypertrophy.

Animals: Data from 38 SB and 18 LB dogs affected with CMVI were compared retrospectively with results from 2 groups of normal dogs (17 SB and 32 LB)

Methods: Systolic function was investigated echocardiographically by using percentage fractional shortening (FS), the ratio between observed and expected end-systolic diameter (ESD/ESDe), and end-systolic volume index (ESVI). Left ventricular hypertrophy was estimated by using the ratio between the thickness of the left ventricular free wall and the radius in diastole (h/R).

Results: Both affected SB and LB dogs had a significantly increased FS and ESVI (FS% SB 45.6 + 8.04 versus 40.06 + 8.9, P < .05; FS% LB 33.64 + 8.61 versus 27.3 + 7.3 P < .05; ESVI SB 30.0 ± 2.3 mL/m2 versus 21.18 ± 13.9 mL/m2, P < .05; ESVI LB 83.22 ± 43.84 mL/m2 versus 36.43 ± 13.30 mL/m2 versus P < .001). The h/R in affected animals was decreased (0.53 ± 0.11 versus 0.41 ± 0.12, P < .05 SB; 0.47 ± 0.11 versus 0.38 ± 0.09, P < .05, LB).

Conclusions and Clinical Importance: Data from this study indicate that dogs with moderate heart failure caused by CMVI have systolic dysfunction. Inadequate hypertrophy of the left ventricle may be, in part, responsible for this finding.

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