Trimethoprim + Sulfamethoxazole Dosing for Dogs, Cats, Horses, Cattle By Weight
Important Information
Doses are listed as the combined sulfonamide + trimethoprim.
For horses: 30 mg/kg (25 mg sulfonamide + 5 mg trimethoprim) for acute treatment. For some infections, treatment once a day at 30 mg/kg may be sufficient.
For cattle: Trimethoprim is not absorbed orally in ruminants, but it is absorbed in calves.
Reference Source
Saunders Handbook of VETERINARY DRUGS, Page 847-849
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Standard Dosage Guidelines
Small Animal Dosage
| Species | Route | Dosage | Frequency |
|---|---|---|---|
| Dogs and Cats | PO | 15-30 mg/kg | q12h |
| IV | 30 mg/kg | q12h |
Large Animal Dosage
| Species | Route | Dosage | Frequency |
|---|---|---|---|
| Horses | PO | 30 mg/kg | q12h |
| Cattle | IV, IM | 16 mg/kg | q24h |
Additional Notes
• Doses are listed as the combined sulfonamide + trimethoprim
• For dogs and cats: 15 mg/kg q12h PO or 30 mg/kg q12-24h PO
• For horses: Acute treatment q12h PO. For some infections, treatment once a day at 30 mg/kg may be sufficient
• For cattle: Trimethoprim + sulfadoxine has been used in cattle (16 mg/kg combined drug every 24 hours IV or IM), but this drug is not available in the US