A 9-year-old 21.7-kg (47.7-lb) spayed female Rottweiler was evaluated because of progressive weakness, lethargy, and diarrhea. Signs of weakness became noticeable approximately 4 weeks prior to evaluation. The dog's weakness progressively worsened, and the diarrhea had been unsuccessfully treated several times during that period. Several days prior to evaluation, the dog developed ascites. The dog was not receiving any medications other than a flea, tick, and heartworm preventative. On physical examination, bradycardia was detected and prompted echocardiographic and ECG examinations to be performed.
An initial lead II ECG tracing revealed an underlying sinus rhythm that was conducted with
A 5.0-kg (11.0-lb) 3-year-old sexually intact male Shih Tzu was referred for investigation of an enlarged heart that had been observed on routine thoracic radiographs by the referring veterinarian. When the patient was a puppy, medical records from the referring veterinarian indicated that a loud left-sided heart murmur was auscultated (murmur timing was not documented). This heart murmur decreased in intensity and was no longer present by 6 months of age. The patient had a recent history of gastrointestinal upset, but had been otherwise apparently healthy.
On physical examination, the patient was bright, alert, and responsive, with a heart