Figure 1.

Flow chart illustrating workflow for proposing DDDbovCA and DCDbovCA values for antimicrobial agents used for cattle in Canada. AM(s), Antimicrobial Agent(s); DDDbovCA, Canadian Defined Daily Dose for cattle; DCDbovCA, Canadian Defined Course Dose for cattle; MIA(s), Medically Important Antimicrobial(s) belonging to the Categories I, II, and III according to Health Canada. ^aInjectable products authorized for lactating dairy cows were assigned to a standard weight of 650 kg. ^bInjectable products not used in lactating dairy cows were assigned to a standard weight of 300 kg. ^cOral products intended for “calves” or “calves up to 136 kg” were assigned to a standard weight of 100 kg. Oral products intended for all types of cattle or for “calves up to 360 kg” were assigned to a standard weight of 300 kg. ^dFor intramammary products for dry cows, a complete treatment for a cow was defined as the infusion of four syringes (one per quarter) at drying off regardless of the product. The complete treatment (4 syringes) was assigned to a duration of action of 10 days meaning that the daily treatment was defined as the infusion of 0.4 syringe per cow, or 0.1 syringe per quarter. ^eFor intramammary products for lactating cows, it was hypothesized that one quarter is infected (and then treated) at a time by cow. ^fFor intrauterine products, when no indication could be found on the product monograph, a duration of action of 24 h was assigned by default. ^gFor topical products, we assumed that 1 mL is sprayed per second (for sprays), 5 g of cream is used per application (for creams), or 5 g of powder is used per application (for powders for topical administration).