Home/Medicines/Losartan
All medicines

Losartan

Prescription
Angiotensin II receptor blocker (ARB)
Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team
Species
Dog
Brands
3 available
Interactions
2 documented
Formulations
2

Mechanism of action

Selectively blocks angiotensin II AT1 receptors, reducing vasoconstriction, aldosterone release, and blood pressure; provides renoprotective effects

At a glance

Class
Angiotensin II receptor blocker (ARB)
Schedule
Prescription
Storage
Store below 25°C, protect from moisture

Dosing

🐕

Dog

Proteinuria / Hypertension (ACE inhibitor alternative)
Dose
0.125–0.5 mg/kg
Route
PO
Frequency
SID to BID
Max dose
25 mg/dose; 50 mg/day
Duration: Long-term

Formulations

💊

Tablet — 2

Strength
25mg
Available in India
Strength
50mg
Available in India

Storage

Store below 25°C, protect from moisture

Safety

Absolute contraindications — do not use

  • Known hypersensitivity

Use with caution

  • Concurrent ACE inhibitor use
    Increased hypotension and hyperkalemia risk

Adverse effects

Common
Mild hypotension
Inappetence
Serious
Hyperkalemia
Acute renal injury

Monitoring parameters

Blood pressureBUN/CreatinineSerum potassium

Interactions

Major — 2

Benazepril
major
Dual RAAS blockade (ARB + ACE inhibitor) increases risk of hyperkalemia, hypotension, and acute kidney injury
Management: Generally avoid. If combined for refractory proteinuria, monitor renal values and potassium closely.
Spironolactone
major
Both cause potassium retention; combined use significantly increases hyperkalemia risk
Management: Monitor serum potassium frequently. Consider alternative diuretic if ARB is required.

Brands

International

Cozaar
MSD

India

Losar
Unichem
Losacar
Cadila

FAQs

Frequently asked questions

›What is Losartan?
Losartan is a angiotensin ii receptor blocker (arb) used in pets. Selectively blocks angiotensin II AT1 receptors, reducing vasoconstriction, aldosterone release, and blood pressure; provides renoprotective effects
›What is Losartan used for in pets?
Losartan is used in veterinary medicine for: Proteinuria / Hypertension (ACE inhibitor alternative).
›What is the Losartan dose for dogs?
For dogs, Losartan is typically dosed as follows — Proteinuria / Hypertension (ACE inhibitor alternative): 0.125–0.5 mg/kg PO SID to BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Losartan?
Common: Mild hypotension, Inappetence. Serious (call your vet immediately): Hyperkalemia, Acute renal injury.
›Does Losartan need a prescription?
Yes. Losartan is a prescription medication and should only be administered under veterinary supervision.
›When should Losartan not be used?
Do not use Losartan if: Known hypersensitivity.

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 (Angiotensin II receptor blocker).

Irbesartan
Rx
Selectively blocks angiotensin II type 1 (AT1) receptors, preventing angiotensin II-mediated vasoconstriction, aldosterone secretion, and cardiac/renal remodeling. Unlike ACE inhibitors, does not cause bradykinin accumulation (no cough).
dogcat
Telmisartan
Rx
Selectively blocks angiotensin II type 1 (AT1) receptors, reducing vasoconstriction, aldosterone secretion, and sympathetic activity; provides renoprotective effects by reducing glomerular pressure
catdog