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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
1

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
PO
Frequency
q24h
🐈

Cat

Limited feline data
Dose
1–2 mg/kg
Route
PO
Frequency
q24–48h

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

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).

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.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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 →

Related medicines

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

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