Veterinary Drug Dosage Calculator
Professional dosage calculator for licensed veterinary professionals. Species-specific dosing with safety checks, formulation conversions, and clinical reference notes for dogs and cats.
Veterinary Professional Access
This tool is designed for licensed veterinary professionals including veterinarians, veterinary technicians, and veterinary students under supervision. It provides drug dosage calculations that require professional clinical judgment to interpret and apply.
Pet owners: Please consult your veterinarian for all medication decisions. Do not administer any medications to your pet without veterinary guidance.
By clicking above, you confirm that you are a licensed veterinary professional or a veterinary student under direct supervision.
How Veterinary Drug Dosing Works
Accurate drug dosing is one of the most fundamental responsibilities in veterinary medicine. Unlike human medicine, where adult patients often receive standardized doses, veterinary patients range from a 1 kg kitten to a 70 kg Great Dane — making weight-based calculations essential for virtually every prescription. The core formula is straightforward: multiply the patient's body weight in kilograms by the prescribed dose rate in mg/kg to obtain the total dose in milligrams. That total dose is then translated into a practical administration quantity based on the available drug formulation.
Species Differences Matter
Dogs and cats are not simply large and small versions of the same patient. Cats lack several key hepatic glucuronidation pathways that dogs rely on for drug metabolism, meaning drugs that are safely cleared by dogs may accumulate to toxic levels in feline patients. Carprofen, a common canine NSAID, can cause fatal reactions in cats. Enrofloxacin must be dose-limited in cats to avoid irreversible retinal degeneration. This calculator enforces species-specific dose ranges and displays prominent warnings when a drug poses known risks to the selected species.
Weight-Based vs. Per-Animal Dosing
Most veterinary drugs use weight-based dosing (mg/kg), where the total dose scales linearly with the patient's body weight. However, certain drugs — particularly those used in cats — employ fixed per-animal dosing. Chlorpheniramine (1–2 mg per cat) and atenolol (6.25–12.5 mg per cat) are dosed per individual rather than per kilogram. This calculator identifies per-animal drugs and handles them accordingly, preventing dangerous over-dosing that could occur if a fixed dose were multiplied by body weight.
Why Formulation Selection Matters
The same drug may be available as tablets, capsules, oral suspensions, or injectable solutions, each at different concentrations. A practical dosing calculation must account for the specific formulation being dispensed. Tablet doses should be rounded to practical fractions (halves or quarters) when possible, while liquid formulations allow more precise dosing — particularly important for small patients where even small errors represent a significant percentage of the intended dose. Injectable concentrations vary widely, and volume calculations must be precise to ensure patient safety.
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Sources & References
- Plumb, D.C. (2018). Plumb's Veterinary Drug Handbook, 9th Edition. Wiley-Blackwell.
- Aiello, S.E., Moses, M.A. (eds.). The Merck Veterinary Manual. Merck & Co.
- U.S. Food & Drug Administration — Approved Animal Drug Products (FDA Green Book)
- Ramsey, I. (ed.). BSAVA Small Animal Formulary, 10th Edition. BSAVA Publications.
FOR VETERINARY PROFESSIONAL USE ONLY
This calculator is a clinical reference tool intended to assist licensed veterinary professionals with drug dosage calculations. It does not replace professional clinical judgment, current formulary references, or patient-specific assessment. Dosages should always be verified against an up-to-date veterinary formulary (e.g., Plumb's Veterinary Drug Handbook, BSAVA Small Animal Formulary). Patient-specific factors including organ function, concurrent medications, age, breed, body condition, and disease state must be considered. PupPilot assumes no liability for clinical decisions made using this tool. Controlled substances are not included and require institutional protocols.
Veterinary Dosage Calculator FAQ
How are veterinary drug dosages calculated?
Most veterinary drug dosages are calculated using the formula: Total Dose (mg) = Patient Weight (kg) x Dose Rate (mg/kg). The total dose is then converted to a practical administration amount based on the drug formulation (tablets, capsules, injectables, or oral suspensions). Some drugs use fixed per-animal dosing rather than weight-based calculations. This calculator automates these conversions and rounds to practical administration increments.
Are all drugs in this calculator safe for both dogs and cats?
No. Dogs and cats have significantly different drug metabolisms. Some drugs that are safe for dogs are contraindicated or require substantially different dosing in cats. For example, carprofen (Rimadyl) should never be used in cats, and enrofloxacin must be limited to 5 mg/kg in cats due to retinal toxicity risk. This calculator filters drugs by species and displays prominent warnings for species-specific contraindications.
Should I adjust dosages for patients with organ dysfunction?
Yes. Patients with hepatic or renal impairment may require dose adjustments that are not reflected in this calculator. Geriatric patients, pediatric patients, and those with concurrent diseases may also need modified dosing. This tool provides standard reference ranges and should be used in conjunction with clinical judgment, patient-specific factors, and current laboratory values.
What is the difference between tablet and injectable dosing?
Tablet doses are expressed as the number of tablets or fractions of tablets needed per dose. Injectable doses are expressed as a volume (mL) calculated from the drug concentration (mg/mL). The total dose in milligrams is the same for both routes, but the administration method differs. Bioavailability may also differ between oral and injectable formulations, which your veterinary formulary will address.
Why are controlled substances not included in this calculator?
Controlled substances (such as opioids, benzodiazepines, and barbiturates) are excluded because they require DEA licensing, specialized record-keeping, and additional safety protocols. Dosing of controlled substances should be performed using institutional protocols, verified against current formulary references, and documented according to federal and state regulations.