The Effect of Combined Therapy With Captopril, Furosemide, and a Sodium‐Restricted Diet on Serum Electrolyte Concentrations and Renal Function in Normal Dogs and Dogs With Congestive Heart Failure

Abstract

Captopril, furosemide, and a sodium-restricted diet were administered t o 6 normal dogs and 10 dogs with congestive heart failure. Serum electrolyte concentrations and renal function were monitored in both groups. In the normal dogs, no clinically meaningful changes in serum electrolyte, urea nitrogen, or creatinine concentrations developed during therapy with a sodium-restricted diet and 4 weeks each of furosemide alone, captopril alone, or furosemide plus captopril. Three of 6 normal dogs on furosemide and a sodium-restricted diet had at least one serum potassium concentration above the reference range during the 4 weeks of observation. One normal dog on captopril, furosemide. and a sodium-restricted diet developed azotemia, and 2 dogs had serum potassium concentrations above the reference range during the 4 weeks of observation. Ten dogs with congestive heart failure were treated with captopril, furosemide, a sodium-restricted diet, and digoxin.herapy for congestive heart failure (CHF) often in-T cludes the use of diuretics and sodium restriction to reduce preload and venous congestion; cardiac glycosides to increase contractility and control supraventricular arrhythmias; and vasodilators to reduce venous congestion, preload, and afterload. Captopril, an inhibitor of angiotensin converting enzyme (ACE), is a popular vasodilator used to treat dogs with CHF. This drug inhibits the formation of angiotensin I1 and results in vasodilation and decreased circulating plasma aldosterone concentrations.' Aldosterone plays an important role in the maintenance of vascular volume and potassium balance via its effects on the renal cortical collecting tubule cell. It also increase the reabsorption of sodium and chloride and promotes the secretion of potassium. The use of ACE inhibitors in human patients with severe renal insufficiency or in those given potassium supplements may increase the risk for h~perkalemia.~.~ It is not known whether the levels of potassium in popular pet foods or sodium-restricted diets will increase the risk for hyperkalemia in dogs receiving ACE inhibitors such as captopril.Functional renal insufficiency has been documented in up to one third of salt-restricted human patients with severe CHF treated with ACE inhibitors and diuretic^.^ This decline in renal function has been attributed to loss of angiotensin Ii-mediated systemic and intrarenal vasoconstrictor effects that maintain renal perfusion pressure and glomerular filtration rate in low output heart failure. Functional renal insufficiency appeared to be alleviated when efforts were made to replenish total body stores of sodium by reducing the diuretic dose and liberalizing dietary sodium intake.' Renal insufficiency is a complication of captopril therapy in dogs with CHF, but the role of sodium restriction is unknown.6 The purpose of this report is to describe the electrolyte concentrations and renal function in both normal dogs and dogs with CHF receiving captopril, furosemide, and a sodium-restricted diet.Etiopathogenesis of the heart failur...

Creatinine in the Dog: A Review

“…Moderate and transient increases in P‐creatinine were observed after treatment with morphine, oxymorphone, ketoprofen, carprofen, ketorolac, and butorphanol 125,126 ; others observed no increase with piroxicam 127 and carprofen 128 . The angiotensin‐converting enzyme (ACE) inhibitors captopril and benazepril caused moderate increases in P‐creatinine, 129,130 whereas enalapril had the same effects as a placebo 131–133 or also caused moderate increases 134 . Cyclosporin 135 and insulin‐like growth factor‐1 (IGF1) 136 also caused moderate increases in P‐creatinine, but cyclosporin was reported to have no effect on P‐creatinine in another case 137 .…”

“…Extracellular dehydration. Prerenal kidney insufficiency caused by furosemide in dogs with heart failure, 130 digoxin, 74 and intraperitoneal administration of iodinated povidone‐iodine 139 were reported to cause increases of P‐creatinine.…”

Clinical, Echocardiographic, and Neurohormonal Effects of a Sodium‐Restricted Diet in Dogs with Heart Failure

“…2,3 In 1994, a study examined the effects of a low-sodium diet and furosemide in healthy dogs with or without captopril. 4 found in that study, 3 of 6 dogs became hyperkalemic while receiving a low-sodium diet plus furosemide and 2 of 6 became hyperkalemic while receiving a low-sodium diet plus furosemide and captopril. 4 The effects of drugs such as furosemide or angiotensin-converting enzyme (ACE) inhibitors alone or potential drug-nutrient interactions can be profound and must be considered.…”

“…The effects of the lowsodium diet alone were not given in the previously reported study. 4 In healthy dogs, low-sodium diets caused increased plasma renin activity (PRA) and plasma aldosterone concentration (PAC) compared to a high-sodium diet, although ACE, atrial natriuretic peptide (ANP), arginine vasopressin (AVP), and endothelin-1 (ET-1) remained unchanged. 5,6 However, healthy dogs that received enalapril while eating a low-sodium diet had an exaggerated increase in PRA and a larger decrease in ACE and ANP compared to a dogs eating a high-sodium diet.…”

Disorders of Potassium

“…In one study, dogs with heart failure receiving furosemide had significantly lower mean serum potassium concentrations (mean serum potassium concentration, 3.9 mEq/L) than did normal dogs (mean serum potassium concentration, 4.4 mEq/L) or * References 11, 63, 75, 119, 134, 135, 157, 159, 160, 163. untreated dogs with arrhythmias (mean serum potassium concentration, 4.3 mEq/L). 165 Penicillin derivatives may cause hypokalemia by acting as nonresorbable anions in the distal tubule and increasing secretion of potassium into tubular fluid. In another study, 10 dogs with congestive heart failure treated with captopril, furosemide, and a sodium-restricted diet did not develop significant changes in serum electrolyte concentrations.…”