Introduction

• Digoxin Digoxin is currently the only positive inotrope, negative chronotrope available. Its positive inotropic actions are via inhibition of the Na+/K+ ATPase and its negative chronotropic effects are via both direct and indirect sympatholytic/parasympathomimetic actions.
• It is utilized most often in the management of systolic dysfunction, ie dilated cardiomyopathy Heart: dilated cardiomyopathy (DCM) , and may be used in the treatment of supraventricular arrhythmias, ie atrial fibrillation Heart: atrial fibrillation.
• The development of more potent agents such as pimobendan Pimobendan , is likely to reduce reliance on this weak positive inotrope for the support of systolic function in dogs.
• Although controversy exists over its use in additional conditions there is little debate that inappropriate or unmonitored digoxin administration may carry significant toxicity.
• While digoxin has been utilized in the management of canine cardiovascular disease for decades, the incidence of digoxin toxicity is poorly documented.
  • One report states that 15.3% of 222 dogs in the enalapril Enalapril clinical studies had serum digoxin concentrations greater than 3.0 ng/ml and 9.1% had signs consistent with digoxin toxicity.
  • A trend toward utilizing lower doses of digoxin and monitoring serum digoxin concentrations will likely reduce the frequency and severity of digoxin intoxication.

Potential toxicities

Predisposing factors

Treatment utilizing digoxin

Recognition of digoxin toxicity

Treatment of digoxin toxicity

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Rathore S S, Curtis J P, Wang Y et al (2003) Association of serum digoxin concentration and outcomes in patients with heart failure. JAMA 289 (7), 871-878 PubMed.
• Merrett D (2000) Digoxin therapy. Aust Vet J 78 (9), 612-615 PubMed.
• Ward D M, Forrester S D, DeFrancesco T C et al (1999) Treatment of severe chronic digoxin toxicosis in a dog with cardiac disease, using ovine digoxin-specific immunoglobulin G Fab fragments. JAVMA 215 (12), 1808-1812 PubMed.
• Synder P S & Panciera D L & Volk L (1993) Digoxin pharmacokinetics in dogs with experimental hypothyroidism. Proc Ann Vet Med Forum (Abstract).

Other sources of information

• Opie L H, Gersh B J (2001) Drugs for the Heart. 5th edition, Philadelphia, W.B. Saunders. Chapter 6, pp 154-186.
• Muir W W III, Sams R A, Moise N S (1999) Textbook of Canine and Feline Cardiology-Principles and Clinical Practice. 2nd edition, Philadelphia, W.B. Saunders. Chapter 17, pp 307-330.
• Sisson D D & Kittleson M D (1999) Textbook of Canine and Feline Cardiology-Principles and Clinical Practice.2nd edition, Philadelphia, W.B. Saunders. Chapter 12, pp 216-250.
• Kittleson M (1998) Small Animal Cardiovascular Medicine. Mosby Inc. p 165.