Practical Matters: Things to remember to calculate chemotherapy dosages correctly

Annette N. Smith
Chemotherapy is usually administered on a m2 (body surface area) basis. While the formula (K x W2/3 )/104 —where K is a constant (10.1 in dogs, 10 in cats) and W is the weight in grams—can be used to calculate body surface area, most veterinarians use a conversion chart found in oncology textbooks or in formularies. When calculating or using conversion charts, it is important to note that the weight used is in grams or kilograms (depending on the formula or conversion chart), not pounds.

It is also important to note that smaller patients may be at an increased risk for toxicosis, especially when receiving agents such as doxorubicin and carboplatin. Many oncologists elect to treat smaller patients on a mg/kg basis. The doxorubicin dose is 1 mg/kg, and the carboplatin dose is 10 mg/kg for dogs < 10 to 15 kg.

Annette N. Smith, DVM, MS, DACVIM (oncology & small animal internal medicine)
Department of Clinical Sciences
College of Veterinary Medicine
Auburn University
Auburn, AL 36849