Today's Veterinary Practice

MAR-APR 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 30 CE: CARDIOVASCULAR AND RENAL DISEASE should be performed to assess heart size and pulmonary vasculature before fluid therapy is begun. Echocardiography is recommended for dogs with radiographic evidence of cardiomegaly and for breeds at risk for dilated cardiomyopathy. Electrocardiography is indicated to further evaluate arrhythmias. Cats Cats may have substantial preclinical heart disease without any obvious abnormalities detected during physical examination. Even for cats with significant cardiomyopathy, thoracic radiographs may be unremarkable. Detection of a murmur, gallop rhythm, arrhythmia, or radiographic cardiomegaly in a cat should prompt further evaluation of heart disease by echocardiography. However, it is impractical to perform echocardiography for every cat before starting fluid therapy. Measuring N-terminal pro B-type natriuretic peptide (NT-proBNP) may be helpful; elevated values suggest a higher likelihood of underlying heart disease warranting further evaluation. This biomarker has been studied in cats with heart disease and can identify cats with moderate to severe echocardiographic changes. 3,4 Although NT- proBNP concentrations can be elevated in cats with hypertension, hyperthyroidism, and severe azotemia, concentrations are not significantly elevated in normotensive cats with mild to moderate (stages 1 to 3) CKD and are not useful indicators of hypertension. 5,6 Recognizing Renal Disease in Dogs and Cats with Cardiovascular Disease In dogs and cats, a routine cardiovascular workup and systemic health examination will probably identify most concurrent renal compromise, although some abnormalities may be subtle. For example, a dog may have International Renal Interest Society stage 1 or 2 CKD ( TABLE 1) 7 but still have a serum creatinine concentration within the reference range (<1.6 mg/ dL [144 mcmol/L]). The only evidence of intrinsic renal disease may be poorly concentrated urine (specific gravity <1.020). Note that cats and dogs receiving diuretic therapy for heart failure will have a low urine specific gravity; thus, urine specific gravity is best evaluated before diuretic therapy is initiated. For patients with known renal compromise (eg, azotemia, proteinuria), the need for cardiovascular diagnostics and imaging should be carefully considered. For dogs and cats with all forms of kidney disease, measurement of systemic blood pressure is always indicated to identify hypertension that can cause end-organ damage. Dogs Sometimes, a useful biomarker for early CKD in dogs is serum symmetric dimethylarginine (SDMA). This marker correlates well with TABLE 1 International Renal Interest Society Staging Scheme for Chronic Kidney Disease in Cats and Dogs 7 STAGE SERUM CREATININE COMMENTS 1 <1.6 mg/dL (cat) <1.4 mg/dL (dog) No clinical signs but evidence of renal issues, such as poorly concentrated urine, proteinuria, and abnormal renal palpation or images 2 1.6–2.8 mg/dL (cat) 1.4–2.0 mg/dL (dog) Mild renal azotemia; minimal clinical signs 3 2.9–5.0 mg/dL (cat) 2.1–5.0 mg/dL (dog) Moderate renal azotemia; variable clinical signs 4 >5.0 mg/dL (cat) >5.0 mg/dL (dog) Severe renal azotemia; substantial compromise

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