Dog · Canis lupus familiaris · typical adult weight 2.00–80.00 kg
Trimethoprim-Sulfamethoxazole is dosed at 15–30 mg/kg PO q12h in dogs, per Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (antimicrobial guidelines working group of the international society for companion animal infectious diseases). Vet Dermatol. 2014;25(3):163-e43. — Plumb's Veterinary Drug Handbook, 10th Ed, p.1195. Trimethoprim-Sulfamethoxazole is used in dogs for Nocardia infections, Pneumocystis pneumonia, Bacterial infections when oral not feasible, UTI, skin infections, prostatitis. Routes documented in dogs: PO. A typical adult dog weighs 2.00–80.00 kg. ExoticRx lists 4 cited dose rules for Trimethoprim-Sulfamethoxazole in dogs, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Bactrim, TMS
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| PO | 15–30 mg/kg | q12h | 6-12 weeks for Nocardia | Nocardia infections | Moderate |
| PO | 15–30 mg/kg | q12h | 21 days minimum | Pneumocystis pneumonia | Moderate | Weese JS, Blondeau J, Boothe D, et al. International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25. doi:10.1016/j.tvjl.2019.02.008 — Plumb's Veterinary Drug Handbook, 10th Ed, p.1195 |
| PO | 15–30 mg/kg | q12h | Until oral feasible | Bacterial infections when oral not feasible | Anecdotal | Plumb's Veterinary Drug Handbook, 10th ed (2023), Sulfa-/Trimethoprim, printed p.1195, DOGS — 'Superficial bacterial folliculitis (extra-label): 15 - 30 mg/kg PO twice daily.31' and 'Complicated UTI: 15 - 30 mg/kg PO every 12 hours32'. Superscript 31 = Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (ISCAID Antimicrobial Guidelines Working Group). Vet Dermatol. 2014;25(3):163-e43. Superscript 32 = Weese JS, Blondeau J, Boothe D, et al. ISCAID guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25.Compilation only — we have not located an independent source that prints this figure. |
| PO | 15–30 mg/kg | q12h | 14-21 days | UTI, skin infections, prostatitis | Strong | Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (antimicrobial guidelines working group of the international society for companion animal infectious diseases). Vet Dermatol. 2014;25(3):163-e43. — Plumb's Veterinary Drug Handbook, 10th Ed, p.1195Compilation only — we have not located an independent source that prints this figure. |
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These ranges are per kg. Enter your dog's weight to get the precise dose and draw-up volume — unit and concentration math done for you.
Sequential blockade of folate synthesis: sulfamethoxazole inhibits dihydropteroate synthase; trimethoprim inhibits dihydrofolate reductase.
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 dogs may differ from canine / feline reference data — consult the primary citations listed with each rule.
Trimethoprim-Sulfamethoxazole dose ranges in dogs, with cited source references: PO 15–30 mg/kg q12h; PO 15–30 mg/kg q12h; PO 15–30 mg/kg q12h; PO 15–30 mg/kg q12h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Trimethoprim-Sulfamethoxazole in dogs: PO.
Cited course lengths for Trimethoprim-Sulfamethoxazole in dogs include: 6-12 weeks for Nocardia; 21 days minimum; Until oral feasible; 14-21 days. Duration depends on the indication — match it to the specific dose rule in the table above.
Trimethoprim-Sulfamethoxazole is indicated in dogs for: Nocardia infections, Pneumocystis pneumonia, Bacterial infections when oral not feasible, UTI, skin infections, prostatitis.
These are general warnings for Trimethoprim-Sulfamethoxazole across species; consult the dog dosing table above for species-specific guidance. May cause keratoconjunctivitis sicca (KCS) in dogs with prolonged use. Can cause bone marrow suppression. Avoid in animals with hepatic disease. Adequate hydration required.
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 dogs — 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.