Clinical Evaluation Of Angiotensin II Inhibitor In The Treatment Of Congestive Heart Failure In Dogs

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Date
2004
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
Congestive heart failure is one of the important cause of morbidity and mortality in dogs. It is often secondary to chronic degenerative mitral valve insufficiency (MVI) and dilated cardiomyopathy (DCM). Presently, judicious inhibition of renin - angiotensin - aldosterone - system remain as the ideal way of treating congestive heart failure. For this purpose, ACE inhibitors, diuretics and digitalis has become the standard therapy. Recently, Angiotensin II blockers were developed and tried in many human trials for hypertension and congestive heart failure. These agents block the angiotensin II at the receptor level thereby causing complete blockade of angiotensin II (eg. Chymase) apart from angiotensin I. With this backdrop, the present study was designed with the objective of assessing the efficacy of Losartan potassium, the first developed angiotensin II blocker in the treatment of CHF in dogs, and to compare its effect with existing standard treatment.Dogs with DCM or MVI were randomly allotted to the treatment groups : group I - Enalapril + furosemide + with / without digoxin, group II - Losartan + furosemide + with / without digoxin and group III enalapril + losartan + furosemide + with / without digoxin. Therapy was carried out for eight weeks and clinical variables, radiography, echocardiography and serum biochemistry were evaluated. In group I and III after 60 days of treatment more per cent of dogs had improved cough scores, respiratory effort, appetite, demeanor, mobility, attitude, activity, pulmonary edema and ascites scores compared to group II, with group III having a slight edge over group I. In heart rate, group I and group III had highly significant (P # 0.01) reduction in heart rate whereas no significant difference was observed in group II after 60 days of treatment. A highly significant (P # 0.01) improvement in fractional shortening and ejection fraction was observed in group I and III whereas no significant changes was observed in group II in DCM dogs after 60 days of treatment. A highly significant (P # 0.01) reduction was observed in LA/Ao ratio in group I and group III whereas no significant difference was observed in group II in MVI dogs at 60 days of treatment. A significant (P # 0.05) difference was observed between group I and group III at 60 days of treatment. In overall evaluation and class of heart failure group I and group III fared very well with group III slightly better than group I, but group II had very poor overall evaluation and improvement in class of heart failure. The level of azotemia was same in all the three treatment groups at 60 days of treatment. The survival rate was more in group III (80%) compared to group II (60%) whereas very poor survival rate (10%) was observed in group II. With the above findings it was concluded that losartan monotherapy was not effective in the treatment of CHF in dogs when compared to the standard therapy and the combination of enalapril and losartan was better than the standard therapy.
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