Incorporating Sales Value into Weight-Based Veterinary Antimicrobial Use Surveillance: An Analysis of Veterinary...

Background/Objectives: Veterinary antimicrobial surveillance has been developed mainly around weight-based indicators, whereas the monetary dimension of antimicrobial sales has been less commonly reported. The Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM) records both sales volume and sales value, enabling the quantity and monetary dimensions of antimicrobial sales to be examined together. The objective of this study was to assess whether examining sales value alongside sales volume could provide additional surveillance information on their temporal trends and distributions across antimicrobial classes and animal species. Methods: We extracted annual veterinary antimicrobial sales data for 2011-2024 from publicly available JVARM reports. We summarized sales volume and sales value overall, by antimicrobial class, by animal category, and by antimicrobial class within each animal category. We examined their joint patterns using two-dimensional volume-value positioning and standardized annual class-specific trajectories and estimated class-specific elasticity and marginal effects using an implied unit price calculated as sales value divided by sales volume. Results: Total sales volume increased from 794 tonnes in 2011 to a peak of 859 tonnes in 2017 and then declined to 745 tonnes in 2024, whereas total sales value increased overall from JPY 19.1 billion in 2011 to JPY 28.7 billion in 2024. In 2024, tetracyclines remained the dominant class by volume at 292 tonnes, whereas cephalosporins, macrolides, and fluoroquinolones were the leading classes by sales value at JPY 4.73, 4.55, and 4.54 billion, respectively. In 2024, pigs ranked first among animal sectors in both sales volume and sales value, at 363 tonnes and JPY 10.28 billion, respectively. Dogs and cats accounted for only 8.6 tonnes but ranked second in sales value at JPY 7.32 billion. The volume-value plots illustrated contrasting positions of antimicrobial classes: tetracyclines, macrolides, and penicillins were located in the high-volume/high-value quadrant; sulfonamides in the high-volume/low-value quadrant; and cephalosporins and fluoroquinolones in the low-volume/high-value quadrant. Standardized trajectories showed concordant movement for some classes but marked divergence for others, most notably tetracyclines, for which sales volume declined while sales value increased. Cephalosporins and fluoroquinolones showed relatively weak proportional responsiveness, with elasticity estimates of -0.70 and -1.00 and marginal effect estimates of -0.03 and -0.05 kg per JPY/g. In contrast, sulfonamides and penicillins showed stronger proportional responsiveness, with elasticity estimates of -1.65 and -1.67, respectively. Conclusions: The joint analysis of sales volume and sales value revealed differences between the two measures in temporal trajectories and the relative prominence of antimicrobial classes and animal sectors. Veterinary antimicrobial use surveillance may therefore benefit from analyzing sales value alongside established sales volume measures, as this approach provides complementary market context.