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Tadalafil

Prescription

Phosphodiesterase-5 (PDE5) Inhibitor

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

2 available

Interactions

1 documented

Formulations

Mechanism of action

Selectively inhibits PDE5, preventing cGMP degradation in pulmonary vascular smooth muscle. Increased cGMP causes vasodilation, reducing pulmonary artery pressure. Longer half-life than sildenafil (17h vs 4h) — allows once-daily dosing.

At a glance

Class

Phosphodiesterase-5 (PDE5) Inhibitor

Schedule

Prescription

Storage

Store at room temperature below 30°C

Dosing

🐕

Dog

Used for pulmonary hypertension (PH)

Dose

1–2 mg/kg

Route

Frequency

q24h

🐈

Cat

Limited feline data

Dose

1–2 mg/kg

Route

Frequency

q24–48h

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 — 1

Strength

—

Storage

Store at room temperature below 30°C

Safety

Monitoring parameters

Echocardiography (tricuspid regurgitation velocity/pressure gradient)Blood pressureExercise toleranceRespiratory rate

Educational reference only

Interactions

Contraindicated — 1

Nitroglycerin (Transdermal)

contraindicated

PDE5 inhibitors potentiate nitric oxide-mediated vasodilation from nitrates. Combined cGMP accumulation causes profound, refractory hypotension that may be fatal.

Management: NEVER combine. Allow 48h washout of tadalafil before nitroglycerin (tadalafil half-life 17h).

Educational reference only

Brands

Other markets

Cialis

Adcirca

FAQs

Frequently asked questions

›What is Tadalafil?

Tadalafil is a phosphodiesterase-5 (pde5) inhibitor used in pets. Selectively inhibits PDE5, preventing cGMP degradation in pulmonary vascular smooth muscle. Increased cGMP causes vasodilation, reducing pulmonary artery pressure. Longer half-life than sildenafil (17h vs 4h) — allows once-daily dosing.

›What is Tadalafil used for in pets?

Tadalafil is used in veterinary medicine for: Used for pulmonary hypertension (PH); Limited feline data.

›What is the Tadalafil dose for dogs?

For dogs, Tadalafil is typically dosed as follows — Used for pulmonary hypertension (PH): 1–2 mg/kg PO q24h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Tadalafil dose for cats?

For cats, Tadalafil is typically dosed as follows — Limited feline data: 1–2 mg/kg PO q24–48h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›Does Tadalafil need a prescription?

Yes. Tadalafil 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

Related medicines

Other medicines in the same class (Phosphodiesterase-5).

Sildenafil

Selectively inhibits PDE5, increasing cGMP levels in pulmonary vascular smooth muscle, causing vasodilation and reducing pulmonary arterial pressure

dogcat