Major Uses

Diltiazem is a calcium channel blocker that is commonly used in dogs, cats, and ferrets to treat hypertension, atrial fibrillation, and supraventricular tachycardias. It can also been used to treat feline hypertrophic cardiomyopathy. When administered with quinidine, it may be useful for treating horses with atrial fibrillation.

Common Precautions

Patients with severe hypotension, sick sinus syndrome or 2nd or 3rd degree AV block, radiographically documented pulmonary congestion, or acute MI should not use diltiazem. Caution should be used when administering this drug to geriatric patients, those with heart failure, or those with hepatic or renal impairment. If diltiazem is being administered via IV, administration should take at least two minutes to prevent complications.

The most common negative side effect associated with diltiazem is bradycardia. Other reported adverse effects include vomiting, lethargy, GI distress, heart block or other rhythm disturbances, hypotension, CNS effects, elevations in liver function tests, and rashes.

Diltiazem should not be used in animals with a known allergy or hypersensitivity to the drug. A veterinarian should be contacted immediately if any concerning symptoms are exhibited or if an overdose occurs.


Diltiazem should be kept at room temperature in a tight, light resistant, childproof container. When using the powder form, solution should be discarded if not used after 24 hours. Diltiazem should be stored where children and pets will not be able to reach it.


A typical dose of diltiazem in dogs is .5-4 mg/kg every 8 hours. For treating cats, a normal dose ranges from .125-3 mg/kg every 8-12 hours. For ferrets, doses range from 2-7.5 mg/kg twice daily. If a dose is forgotten, it should be administered as soon as possible. If it is nearing time for the next scheduled dose, the missed dose should be skipped and the normal medication schedule should continue. Two doses should not be administered at the same time.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.