From Dog

Verapamil is a calcium channel blocker used for treatment of supraventricular tachycardia and in conjunction with digoxin for management of congestive heart failure in dogs.

This drug impairs the entry of calcium ions into cardiac muscle, specialized cardiac nodal tissues, or vascular smooth muscle.

Recommended dose rate is 0.1 to 0.2 mg/kg orally ever 8 hours.