Calculation of standard bodyweights for dogs, cats, rabbits, and guinea pigs

O'Neill, Daniel; Becker, Stuart D.; Frosini, Siân-Marie; Stapleton, Laura E.; Hughes, David M.; Brodbelt, Dave C.

Abstract

Standard bodyweights are an essential component of calculations that summarise many
population-level measures in companion animals, including the defined daily doses for
veterinary species (DDDVet) reporting antimicrobial usage. Standard species bodyweights
may originate from data derived from clinical records, but current methods to obtain these
values risk inaccuracy because they exclude measurements obtained from juvenile animals
and consider only individuals that have achieved stable adult bodyweight. This study
aimed to improve the accuracy of standard population level species bodyweights through
the development of a prediction modelling approach to estimate point mean population
bodyweight in dogs, cats, rabbits, and guinea pigs. Data were obtained from the VetCompass
database and included bodyweight measurements from approximately three million
dogs, two million cats, 220,000 rabbits and 62,000 guinea pigs across 1,800 veterinary
practices in the United Kingdom. Initially, Loess models were used to identify the age at
which juvenile animals transitioned from growth to stable adult bodyweight. Linear mixed
effects models were developed to predict juvenile growth, calibrated such that predicted
cessation of growth matched that observed in the Loess models. The prediction models
were then used to adjust bodyweight measurements obtained from clinical records of
juvenile patients, allowing historical measurements to be included for estimation of a point
mean population bodyweight on a subsequent specified target date. Juvenile growth transitioned
to stable adult bodyweight at approximately 14 months in dogs, and 13 months
in cats, rabbits, and guinea pigs. Point mean whole-population bodyweights estimated on
31st December for each year 2014 – 2023 found that the mean bodyweight of cats, rabbits,
and guinea pigs was approximately 4.2 kg, 2.3 kg, and 1.0 kg respectively and changed
little over this time period. However, dogs showed a trend to lower mean bodyweight over
time, with a mean value of 17.6 kg in 2014, reducing to 16.1 kg by 2023.

Citation

O'Neill, D., Becker, S. D., Frosini, S.-M., Stapleton, L. E., Hughes, D. M., & Brodbelt, D. C. (2025). Calculation of standard bodyweights for dogs, cats, rabbits, and guinea pigs. PLoS ONE, 20(2), e0318734. https://doi.org/10.1371/journal.pone.0318734

• Journal Article Type: Article
• Acceptance Date: Jan 1, 2025
• Online Publication Date: Feb 13, 2025
• Publication Date: Feb 13, 2025
• Deposit Date: Feb 14, 2025
• Publicly Available Date: Feb 27, 2025
• Journal: PLOS ONE
• Electronic ISSN: 1932-6203
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: 2
• Pages: e0318734
• DOI: https://doi.org/10.1371/journal.pone.0318734
• Publisher URL: https://doi.org/10.1371/journal.pone.0318734