Hydrolyzes to formaldehyde in acidic urine (pH < 6.0), which is bactericidal; requires urinary acidification to be effective
Dosing
Recurrent UTI prophylaxis (not acute treatment)
Max dose
1000 mg/dose; 3000 mg/day
Duration: Long-term prophylaxis; must maintain urine pH < 6.0
Recurrent UTI prophylaxis
Max dose
250 mg/dose; 750 mg/day
Duration: Long-term prophylaxis; maintain acidic urine
Safety
Absolute contraindications — do not use
Alkaline urine
Drug is ineffective at pH > 6.5
Concurrent urease-producing infections (Proteus, Staphylococcus)
These organisms alkalinize urine
Adverse effects
Serious
Bladder irritation
Hematuria (at high formaldehyde concentrations)
Urine pH (must remain < 6.0)Urine cultureRenal function
Interactions
No documented interactions.
Brands
India
Hexamine
Leeford Healthcare
FAQs
Frequently asked questions
›What is Methenamine (Hexamine)?
Methenamine (Hexamine) is a urinary antiseptic used in pets. Hydrolyzes to formaldehyde in acidic urine (pH < 6.0), which is bactericidal; requires urinary acidification to be effective
›What is Methenamine (Hexamine) used for in pets?
Methenamine (Hexamine) is used in veterinary medicine for: Recurrent UTI prophylaxis (not acute treatment); Recurrent UTI prophylaxis.
›What is the Methenamine (Hexamine) dose for dogs?
For dogs, Methenamine (Hexamine) is typically dosed as follows — Recurrent UTI prophylaxis (not acute treatment): 10–20 mg/kg PO TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Methenamine (Hexamine) dose for cats?
For cats, Methenamine (Hexamine) is typically dosed as follows — Recurrent UTI prophylaxis: 10–20 mg/kg PO TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Methenamine (Hexamine)?
Common: GI irritation, Nausea. Serious (call your vet immediately): Bladder irritation, Hematuria (at high formaldehyde concentrations).
›Does Methenamine (Hexamine) need a prescription?
Yes. Methenamine (Hexamine) is a prescription medication and should only be administered under veterinary supervision.
›When should Methenamine (Hexamine) not be used?
Do not use Methenamine (Hexamine) if: Renal insufficiency.
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.
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