Assignment of Canadian Defined Daily Doses and Canadian Defined Course Doses for Quantification of Antimicrobial Usage in Cattle

Abstract

Standardized units are essential to allow quantification and comparison of antimicrobial usage (AMU) between species and regions. In Canada, defined daily and course doses have not yet been harmonized for cattle. Our objective was to assign defined daily and course doses (named DDDbovCA and DCDbovCA, respectively) for cattle in Canada, by antimicrobial agent (AM) and by route of administration, based on the label of all products containing at least one AM, marketed and authorized in Canada for use in cattle. In April and December 2019, a systematic search was performed from the online Drug Product Database (DPD) of Health Canada to identify veterinary products containing at least one AM, marketed in Canada for use in cattle. Products were divided by route of administration (intramammary, intrauterine, injectable, oral, and topical). The monograph was retrieved for each product from the DPD, or from the Canadian Edition of the Compendium of Veterinary Products (CVP), and read completely to extract recommended dosages in cattle. Standard weights were applied to compute doses if required. DDDbovCA and DCDbovCA were assigned by calculating an average of daily and course doses, respectively, by AM and route of administration. Two products were excluded from calculations because of their claim as growth promotion or feed efficiency (no longer authorized in Canada for certain categories of AM). Overall, 39 injectable, 75 oral (including 23 medicated premixes), 8 intramammary (4 for lactating cows and 4 for dry cows), 5 intrauterine, and 4 topical products were used for calculations. DDDbovCA and DCDbovCA values were assigned successfully for each AM identified, by route of administration. These metrics will allow harmonized and transparent quantification of AMU in cattle in Canada.

Evaluation of an OPEN Stewardship generated feedback intervention to improve antibiotic prescribing among primary care veterinarians in Ontario, Canada and Israel: protocol for evaluating usability and an interrupted time-series analysis

“…The primary outcome of the interrupted time-series portion of the study is the monthly antibiotic prescribing rate (number of defined daily doses of antibiotics prescribed per 100 cases). The defined daily doses of antimicrobials used for dairy cattle will be calculated according to Lardé et al 49 while a modification of this approach will be used to calculate the defined daily dose for antibiotics used in companion animals. The secondary outcomes of the study are (1) the rate of antibiotic prescribing for drug classes deemed critically important for human medicine (number of defined daily doses of critically important antibiotics prescribed per 100 cases), (2) the mean duration of antibiotic prescribing, and (3) the rate of prescribing broad-spectrum antibiotics (number of defined daily doses of broad-spectrum antibiotics prescribed per 100 cases) for a specific condition (eg, mastitis in cattle, and acute respiratory tract infection in companion animals).…”

Establishing defined daily doses (DDDs) for antimicrobial agents used in pigs, cattle and poultry in Japan and comparing them with European DDD values

“…A comparison of DDDjps and DDDvet for antimicrobials destined for intramammary administration was not made in our study, because DDDvet values were not available in mg/ kg/day. The DDDjp values for these antimicrobials were assigned in mg/kg/day assuming a standard weight at treatment and long-acting factor (for intramammary products for dry cows) to make them comparable with the DDD values of other countries defined in mg/kg/ day (e.g., Canada [25]). However, the DDD values for dry cows are greatly affected depending on what values are used as a long-acting factor: we used a long-acting factor of four days in the same way as the Netherlands, whilst Germany and Canada used a long-acting factor of seven and ten days respectively, in assigning their DDD values for intramammary products for dry cows [25].…”

“…The DDDjp values for these antimicrobials were assigned in mg/kg/day assuming a standard weight at treatment and long-acting factor (for intramammary products for dry cows) to make them comparable with the DDD values of other countries defined in mg/kg/ day (e.g., Canada [25]). However, the DDD values for dry cows are greatly affected depending on what values are used as a long-acting factor: we used a long-acting factor of four days in the same way as the Netherlands, whilst Germany and Canada used a long-acting factor of seven and ten days respectively, in assigning their DDD values for intramammary products for dry cows [25]. These periods are not representative of the exact true duration of action for each product but approximations and are defined strictly for allowing assignment of daily doses in a transparent way.…”

Antimicrobial Use Surveillance Indicators for Finfish Aquaculture Production: A Review

“…Some use the terms interchangeably, while others differentiate between them and define an AMU metric to be a technical unit of measurement (e.g., frequency of use) and an indicator to be an AMU measurement in relation to a denominator such as animal biomass, population size or time unit ( 17 ). This becomes confusing when considering, for example, the Population Correction Unit (PCU) and Defined Daily Dose Animal (DDDvet) for a given antimicrobial ( 17 , 20 , 23 , 24 ). The PCU and DDDvet, by definition, are not AMU metrics because they do not quantify AMU.…”

“…Countries outside the EU may have different approved drug label dosages that lead to country-specific DDDvet definitions. Canada has defined Canadian industry-specific DDDvetCAs for swine, chickens, turkeys and cattle ( 20 , 24 , 30 ). Typical drug labels for in-feed or water administration for these species use inclusion rates of mg AMD per 1,000 kg of feed or 1,000 L of water.…”