Methenamine Hippurate
Also known as: Hiprex, Urex
* **Administration:** Give this medication exactly as prescribed. If your pet experiences stomach upset (vomiting or loss of appetite), try giving the medication **after meals**. * **Dietary Importance:** This drug *only* works if your pet's urine is acidic. It is critical to strictly feed any special prescription diets or administer urinary acidifiers exactly as directed by your veterinarian. * **Compliance:** Do not skip doses. Consistent administration is required to prevent recurrent infections. * **Monitoring:** Your veterinarian will likely need to check your pet's urine pH regularly to ensure the medication is working properly.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Urinary tract infection prophylaxis
- Urinary tract infection prophylaxis
- Urinary tract infection prophylaxis
- Urinary tract infection prophylaxis
How it is given
Possible side effects
- Gastrointestinal irritation (nausea, vomiting, anorexia)
- Dysuria (secondary to formaldehyde irritation with long-term use)
- Systemic acidosis (potential)
- Lipoid pneumonitis (reported in humans using oral suspension)
Cautions & contraindications
- Hypersensitivity to methenamine or its salts
- Renal insufficiency
- Metabolic acidosis
- Severe hepatic impairment (due to ammonia production during hydrolysis)
- Severe dehydration
- > **Crucial Efficacy Requirement:** Urine pH MUST be kept below 6.5 (ideally ≤ 5.5) for the drug to be effective. * **Urea-Splitting Bacteria:** Infections with urea-splitting organisms (e.g., *Proteus*, some *Staphylococcus*, *Pseudomonas*) naturally alkalinize the urine, potentially rendering methenamine ineffective. * **Acidification Therapy:** Concurrent use of urinary acidifiers (e.g., methionine, ammonium chloride, ascorbic acid) or prescription acidifying diets is often required. * **Species Sensitivity:** Cats reportedly do not tolerate methenamine as well as dogs. * **Pregnancy:** FDA Category C. Crosses the placenta; use with caution during pregnancy. Enters milk, but no adverse effects reported in nursing offspring.
Drug interactions
- Sulfamethiazole: Not recommended; an insoluble precipitate may form in the urine.
- Urine Alkalinizing Drugs (e.g., calcium/magnesium antacids, carbonic anhydrase inhibitors, citrates, sodium bicarbonate, thiazide diuretics): May reduce the efficacy of methenamine by preventing its conversion to formaldehyde in the urine.
Frequently asked questions
What is Methenamine Hippurate used for in pets?
* **Administration:** Give this medication exactly as prescribed. If your pet experiences stomach upset (vomiting or loss of appetite), try giving the medication **after meals**. * **Dietary Importance:** This drug *only* works if your pet's urine is acidic. It is critical to strictly feed any special prescription diets or administer urinary acidifiers exactly as directed by your veterinarian. * **Compliance:** Do not skip doses. Consistent administration is required to prevent recurrent infections. * **Monitoring:** Your veterinarian will likely need to check your pet's urine pH regularly to ensure the medication is working properly.
Is Methenamine Hippurate safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Worried about your pet?
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app