Sequential blockade of folate synthesis: sulfadiazine inhibits dihydropteroate synthase and trimethoprim inhibits dihydrofolate reductase, producing synergistic bactericidal activity
At a glance
Class
Sulfonamide + Diaminopyrimidine antibiotic combination
Storage
Store below 25°C, protect from light
Dosing
Susceptible bacterial infections (UTI, skin, respiratory)
Max dose
1500 mg/dose; 3000 mg/day
Duration: 7–14 days; avoid >14 days continuous
Susceptible bacterial infections
Max dose
400 mg/dose; 800 mg/day
Duration: 7–14 days
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 →Safety
Absolute contraindications — do not use
Hepatic insufficiency
Dobermans may be predisposed to sulfonamide hypersensitivity
Keratoconjunctivitis sicca risk
Prolonged use may cause KCS
Adverse effects
Common
Inappetence
Vomiting
Diarrhoea
Serious
KCS (dry eye)
Hepatotoxicity
Blood dyscrasias
Sulfonamide crystalluria
Schirmer tear test (prolonged use)CBCUrinalysis
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 →Interactions
No documented interactions.
Brands
India
Sulphatrim-Vet
TTK Healthcare
FAQs
Frequently asked questions
›What is Sulfadiazine + Trimethoprim?
Sulfadiazine + Trimethoprim is a sulfonamide + diaminopyrimidine antibiotic combination used in pets. Sequential blockade of folate synthesis: sulfadiazine inhibits dihydropteroate synthase and trimethoprim inhibits dihydrofolate reductase, producing synergistic bactericidal activity
›What is Sulfadiazine + Trimethoprim used for in pets?
Sulfadiazine + Trimethoprim is used in veterinary medicine for: Susceptible bacterial infections (UTI, skin, respiratory); Susceptible bacterial infections.
›What is the Sulfadiazine + Trimethoprim dose for dogs?
For dogs, Sulfadiazine + Trimethoprim is typically dosed as follows — Susceptible bacterial infections (UTI, skin, respiratory): 15–30 mg/kg PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Sulfadiazine + Trimethoprim dose for cats?
For cats, Sulfadiazine + Trimethoprim is typically dosed as follows — Susceptible bacterial infections: 15–30 mg/kg PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Sulfadiazine + Trimethoprim?
Common: Inappetence, Vomiting, Diarrhoea. Serious (call your vet immediately): KCS (dry eye), Hepatotoxicity, Blood dyscrasias, Sulfonamide crystalluria.
›Does Sulfadiazine + Trimethoprim need a prescription?
Yes. Sulfadiazine + Trimethoprim is a prescription medication and should only be administered under veterinary supervision.
›When should Sulfadiazine + Trimethoprim not be used?
Do not use Sulfadiazine + Trimethoprim if: Sulfonamide hypersensitivity.
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 →References
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