An in-depth look at dilated cardiomyopathy in dogs in England

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An extensive retrospective study in the January 2009 Journal of Small Animal Practice reviewed the records of 369 dogs that had been diagnosed with dilated cardiomyopathy over a 13-year period at a specialty center. The authors wanted to identify which signalment and clinical findings could help practitioners more readily identify this devastating and deadly disease in dogs, perhaps helping them to catch it earlier and achieve a better prognosis. Although this study delineated the disease in dogs in England, the findings have value for practices worldwide.

Dilated cardiomyopathy occurred more often in male dogs (a male to female ratio of 2.7 to 1) that were medium or large purebreds (only four dogs were mixed-breed). Some breed differences in sex were striking-the male to female ratio in Great Danes and German shepherds was about 6 to 1 and in Doberman pinschers and Saint Bernards was about 5 to 1. The most common breeds affected were Doberman pinschers, boxers, Great Danes, cocker spaniels, and German shepherds. Most Doberman pinschers and boxers were between 5 and 10 years old, but there were no obvious age patterns with the other commonly presented breeds. Two-thirds of the dogs presented in stage 3 heart failure. The most frequent presenting signs were breathlessness, coughing, and exercise intolerance, and the most common clinical finding was a weak pulse. Breed differences were seen in clinical signs on presentation, including boxers primarily experiencing collapse, golden retrievers experiencing reduced appetites, and Great Danes experiencing weakness. Only one-third of dogs had a murmur, and the average heart rate, measured by ECG, was 175 beats/min. Atrial fibrillation was present in 45% of the dogs, 31% had ventricular premature complexes, and 89% had some type of arrhythmia. The 11% that did not have an arrhythmia had abnormalities in their waveforms that indicated cardiomegaly or ischemia, so the authors concluded that completely normal results on an ECG could be a sensitive rule-out test for dilated cardiomyopathy but do not advocate its use as such. An enlarged heart was evident on radiographs in 80% of the dogs, and pulmonary edema or pleural effusion was noted in 74% of the dogs. The median survival time in the dogs was 19 weeks, with a mean survival time of 50.2 weeks.  The survival rate at one year was 28% and at two years, was 14%.

Martin MWS, Stafford Johnson MJ, Celona B. Canine dilated cardiomyopathy: a retrospective study of signalment, presentation and clinical findings in 369 cases. J Small Anim Pract 2009;50(1):23-29.

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