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Hydralazine

Prescription

Direct Arteriolar Vasodilator

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

1 available

Interactions

2 documented

Formulations

Mechanism of action

Directly relaxes arteriolar smooth muscle reducing systemic vascular resistance (afterload). No significant venodilation. Reflex tachycardia and renin-angiotensin activation occur.

At a glance

Class

Direct Arteriolar Vasodilator

Schedule

Prescription

Storage

Store at room temperature, protect from light

Dosing

🐕

Dog

Used for afterload reduction in mitral regurgitation and systemic hypertension

Dose

0.5–2 mg/kg

Route

PO, IV

Frequency

q12h

🐈

Cat

Used for feline hypertension

Dose

0.5–1 mg/kg

Route

Frequency

q12h

Educational reference only

This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Other — 2

Strength

—

Strength

—

Storage

Store at room temperature, protect from light

Safety

Monitoring parameters

Blood pressure (baseline, 2h post-dose, q48h during titration)Heart rateRenal functionBody weight

Educational reference only

Interactions

Moderate — 2

Propranolol

moderate

Beta-blocker attenuates hydralazine-induced reflex tachycardia. Additive blood pressure reduction.

Management: Intentional combination to control reflex tachycardia. Monitor blood pressure and heart rate closely during titration.

Furosemide

moderate

Additive blood pressure reduction. Both reduce preload/afterload via different mechanisms.

Management: Standard heart failure combination. Monitor blood pressure. Start hydralazine at low dose.

Educational reference only

Brands

Other markets

Apresoline

FAQs

Frequently asked questions

›What is Hydralazine?

Hydralazine is a direct arteriolar vasodilator used in pets. Directly relaxes arteriolar smooth muscle reducing systemic vascular resistance (afterload). No significant venodilation. Reflex tachycardia and renin-angiotensin activation occur.

›What is Hydralazine used for in pets?

Hydralazine is used in veterinary medicine for: Used for afterload reduction in mitral regurgitation and systemic hypertension; Used for feline hypertension.

›What is the Hydralazine dose for dogs?

For dogs, Hydralazine is typically dosed as follows — Used for afterload reduction in mitral regurgitation and systemic hypertension: 0.5–2 mg/kg PO/IV q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Hydralazine dose for cats?

For cats, Hydralazine is typically dosed as follows — Used for feline hypertension: 0.5–1 mg/kg PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›Does Hydralazine need a prescription?

Yes. Hydralazine is a prescription medication and should only be administered under veterinary supervision.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database