Trimethoprim-Sulfamethoxazole for Horse
Equine · Equus caballus · typical adult weight 350.00–700.00 kg
Trimethoprim-Sulfamethoxazole is used in horse for Severe bacterial infection, Bacterial infection, Susceptible bacterial infections. Routes documented in horse: IV, PO. A typical adult horse weighs 350.00–700.00 kg. ExoticRx lists 3 cited dose rules for Trimethoprim-Sulfamethoxazole in horse, drawn from published veterinary references. Verify against current literature before clinical use.
Trade names: Bactrim, TMS
Dose ranges
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| IV | 24 mg/kg | q12h | 5-7 days | Severe bacterial infection | Moderate | Plumb's Veterinary Drug Handbook, 9th Ed |
| PO | 24–30 mg/kg | q12h | 7-14 days | Bacterial infection | Strong | Plumb's Veterinary Drug Handbook, 9th Ed |
| PO | 24–30 mg/kg | q12h | 7-14 days | Susceptible bacterial infections | Strong | Plumb's Veterinary Drug Handbook |
Need the exact dose for your patient?
These ranges are per kg. Enter your horse's weight to get the precise dose and draw-up volume — unit and concentration math done for you.
Mechanism of action
Sequential blockade of folate synthesis: sulfamethoxazole inhibits dihydropteroate synthase; trimethoprim inhibits dihydrofolate reductase.
Side effects & warnings
May cause keratoconjunctivitis sicca (KCS) in dogs with prolonged use. Can cause bone marrow suppression. Avoid in animals with hepatic disease. Adequate hydration required.
Species-specific contraindications and adverse-reaction reports for horse may differ from canine / feline reference data — consult the primary citations listed with each rule.
Other Antibiotic drugs with horse dosing
Trimethoprim-Sulfamethoxazole dosing in other species
Why a species-specific page? Trimethoprim-Sulfamethoxazole pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in horse — the rules above are the citations specific to this species, not generic recommendations.
Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.