Overview of Digoxin for Dogs and Cats

Digoxin, known as Cardoxin® or Lanoxin®, is used to treat heart failure and various heart-rhythm abnormalities in dogs and cats. 

Heart failure is usually associated with a reduced ability of the heart muscle to contract. Drugs that stimulate the contraction of the heart are called cardiotonics or positive inotropic drugs. These drugs work by increasing the availability of calcium to the heart muscle.

Digoxin is an inotropic drug belonging to a class of drugs known as cardiac glycosides and was originally produced from the foxglove flower.

Digoxin increases contraction strength of the heart, which increases the amount of blood pumped out of the heart. This effect is modest.

Digoxin will reduce nerve stimulation to the heart that would normally result in an increased heart rate. With less stimulation, the heart rate slows.

Digoxin is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.

Brand Names and Other Names of Digoxin 

This drug is registered for use in animals and humans.

Human formulations: Lanoxin® (Elkins-Sinn), Lanoxicaps® (Glaxo Wellcome) and various generics

Veterinary formulations: Cardoxin® (Evsco) and various generics

Uses of Digoxin for Dogs and Cats

Digoxin is used to treat heart failure and various heart-rhythm abnormalities, particularly atrial fibrillation. For the latter purpose it may be combined with other drugs.

Digoxin does not prolong life but does reduce symptoms of heart failure.

Effective use of the drug is best monitored by a test that measures concentration of digoxin in the blood.

Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, digoxin can cause side effects in some animals.

Digoxin should not be used in animals with known hypersensitivity or allergy to the drug.

Digoxin should be avoided in animals with moderate to severe kidney failure, severe lung disease, and certain heart diseases (such as pericardial disease).

Extreme care must be taken to administer the prescribed dose of digoxin. The toxic concentration and therapeutic concentration are very similar.

Digoxin may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with digoxin. Such drugs include cimetidine, antacids, certain antibiotics and thyroid replacement therapy. A number of drugs interact with digoxin to raise the blood level and predispose to a toxic reaction. Examples are diazepam, verapamil and quinidine.

High doses of digoxin can lead to adverse effects, including cardiac arrhythmias, loss of appetite, vomiting and diarrhea.

How Digoxin Is Supplied

Digoxin is available in 0.05 mg, 0.1 mg, 0.125 mg, 0.2 mg, 0.25 mg, and 0.5 mg tablets.

It is also available in a 0.05 mg/ml and 0.15 mg/ml elixir.

Digoxin injectable is available in a 0.1 mg/ml concentration.

Dosing Information of Digoxin for Dogs and Cats

Medication should never be administered without first consulting your veterinarian.

In dogs, 0.00125 to 0.0015 mg per pound (0.0025 to 0.003 mg/kg) twice daily. 

In cats, 1/4 of a 0.125 mg tablet once daily or every other day.

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.