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. 2020 Mar 22.
doi: 10.1111/jvim.15753. Online ahead of print.

Temporal Changes in Clinical and Radiographic Variables in Dogs With Preclinical Myxomatous Mitral Valve Disease: The EPIC Study

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Temporal Changes in Clinical and Radiographic Variables in Dogs With Preclinical Myxomatous Mitral Valve Disease: The EPIC Study

Adrian Boswood et al. J Vet Intern Med. .
Free article


Background: The Evaluation of pimobendan in dogs with cardiomegaly caused by preclinical myxomatous mitral valve disease (EPIC) study monitored dogs with myxomatous mitral valve disease (MMVD) as they developed congestive heart failure (CHF).

Objectives: To describe the changes in clinical and radiographic variables occurring as dogs with MMVD and cardiomegaly develop CHF, compared to similar dogs that do not develop CHF.

Animals: One hundred and thirty-five, and 73 dogs that did or did not develop CHF, respectively.

Materials and methods: The following variables were evaluated in 2 groups of dogs (dogs that did or did not develop CHF): Heart rate (HR), clinic respiratory rate (RR), home-measured resting respiratory rate (RRR), rectal temperature (RT), body weight (BW), and vertebral heart sum (VHS). Absolute value and rate of change of each variable were calculated for each day a dog was in study. Daily means were calculated and plotted against time. The onset of CHF or last visit before leaving the study were set as reference time points.

Results: The most extreme values and rate of change occurred in variables immediately before onset of CHF. Vertebral heart sum increased earliest. Heart rate, RR, and RRR also increased. Rectal temperature and BW decreased. Increases in RR and RRR were most extreme and occurred immediately before CHF.

Conclusions and clinical importance: Dogs with MMVD and cardiomegaly experience increases in HR, RR, RRR, and VHS, and decreases in BW and RT as they develop CHF. The variables with highest absolute change and rate of change were RR and RRR. These findings reinforce the value of RR and RRR as indicators of impending or incipient CHF.

Keywords: canine; cardiovascular; clinical epidemiology; clinical trials; heart failure; physical examination; radiology and diagnostic imaging.

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    1. Boswood A, Gordon SG, Haggstrom J, et al. Longitudinal analysis of quality of life, clinical, radiographic, echocardiographic, and laboratory variables in dogs with preclinical myxomatous mitral valve disease receiving Pimobendan or placebo: the EPIC study. J Vet Intern Med. 2018;32:72-85.
    1. Boswood A, Haggstrom J, Gordon SG, et al. Effect of pimobendan in dogs with preclinical myxomatous mitral valve disease and cardiomegaly: the EPIC study-a randomized clinical trial. J Vet Intern Med. 2016;30:1765-1779.
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    1. Hezzell MJ, Boswood A, Moonarmart W, Elliott J. Selected echocardiographic variables change more rapidly in dogs that die from myxomatous mitral valve disease. J Vet Cardiol. 2012;14:269-279.

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