Today's Veterinary Practice

JUL-AUG 2015

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tvpjournal.com | July/August 2015 | TodAy's VeTerinAry PrAcTice HeArT FAilure in dogs: 6 PrAcTicAl TiPs From cArdiologisTs Peer reviewed 27 DMVD, and a loud murmur is more likely with advanced disease. See Consider These Cases (#2). • A rapid heart rate, most often a sinus tachycardia (Figure 2), is associated with epinephrine and increased sympathetic drive in heart failure. A normal heart rate or respiratory sinus arrhythmia (Figure 3) suggests an absence of sympathetic drive and indicates that heart failure is not the most likely cause of respiratory signs. • Are there other signs of potential heart disease, including a gallop or arrhythmia? » As the atria increase in size, dogs may develop supraventricular arrhythmias, such as premature beats, bursts of supraventricular tachycardia, and atrial fbrillation. An arrhythmia may be heard during auscultation of the thorax or appreciated upon palpation of pulses. » Pulses may be irregular, weak, or occasionally absent. An S 3 gallop can be heard in dogs with DCM associated with rapid ventricular flling into an enlarged, poorly contracting and relaxing ventricle. 3. Know When to Test Thoracic radiographs and serum biochemistries are complementary: Radiographs are critical for assessing cough or respiratory signs and monitoring heart failure therapy. Thoracic radiographs provide information on measures of heart size (ie, number of rib spaces, vertebral heart size), specifc chamber enlargement, pulmonary vessel size, and pulmonary patterns. FIGURE 2. Lead II electrocardiogram demonstrating sinus tachycardia with a regular rhythm and heart rate of 175 beats/min in a dog with CHF (25 mm/s; 10 mm/mV). FIGURE 3. Lead II electrocardiogram demonstrating sinus arrhythmia with an irregular rhythm and heart rate of 80 beats/min in a dog with a murmur, chronic cough, and tracheal collapse (25 mm/s; 10 mm/mV). Consider These Cases Case #1: A 9-year-old castrated male golden retriever was presented for increased respiratory rate and restlessness. Initially, on the basis of signalment, the clinician considered pericardial effusion and a heart base tumor as possible differential diagnoses. However, the owner remembered that the dog had a murmur as a puppy. During the physical examination, a grade 4/6 systolic left basilar murmur was auscultated and heart sounds were not muffed. Congenital subaortic stenosis resulting in left-sided CHF (ie, pulmonary edema) was subsequently diagnosed. Case #2: Consider the case presented on page 26—the 8-year-old castrated male bichon frise with 6-month history of exercise-induced cough and a grade 3/6 systolic left-sided heart murmur, whose owner reported coughing during the night and labored breathing. When you auscultate the dog, the murmur has increased to a grade 4/6 systolic left apical murmur. Based on clinical presentation, which scenario outlined in Table 2 is more consistent with heart failure in this patient? Scenario 2—demonstrating increased heart and respiratory rates compared with Scenario 1—is consistent with CHF in this coughing dog with a heart murmur. Tabl E 2. Physical Examination Scenarios: Coughing Dog with Heart Murmur PARAMETERS SCENARIO 1 SCENARIO 2 Heart rate 110 beats/min 170 beats/min Respiratory rate 35 breaths/min 80 breaths/min

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