How to Calculate Dog Medication Dosage
What is Dog Medication Dosage?
Canine drug doses are weight-based (mg/kg). Many human medications are toxic to dogs. Always verify dosing with your veterinarian — never extrapolate human doses.
Formula
Dose = Dog weight (kg) × Dose per kg; Body surface area (BSA) dose = BSA (m²) × Dose per m²; BSA (m²) = (Weight in g ^ 0.67) / 10,000
- Weight
- Dog body weight (kg)
- DosePerKg
- Prescribed dose per kg (mg/kg (varies by drug))
- Dose
- Total dose to administer (mg)
Step-by-Step Guide
- 1Dose (mg) = Weight (kg) × Dose rate (mg/kg)
- 2Frequency determined by drug half-life
- 3Never give ibuprofen, naproxen, paracetamol/acetaminophen to dogs
- 4Maximum doses apply regardless of weight
Worked Examples
Input
Amoxicillin 20mg/kg, 30 kg dog
Result
Total dose = 600mg; every 12 hours
Frequently Asked Questions
Why do dog doses differ from human doses?
Dogs metabolize drugs faster (higher basal metabolism). BSA-based dosing accounts for surface area scaling. Small dogs need proportionally higher doses; large dogs lower.
Should I use weight or BSA for dosing?
Weight-based: simpler, most antibiotics/pain meds. BSA-based: better for chemotherapy, some cardiovascular drugs. Check veterinary reference; most use weight nowadays.
What if I miss a dose?
Give as soon as remembered unless close to next dose (> 2 hrs away). Don't double next dose. Chronic meds (thyroid, pain): missing 1 dose rarely critical. Call vet if unsure.
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