{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T18:07:58Z","timestamp":1789063678793,"version":"build-2803163510"},"reference-count":14,"publisher":"American Veterinary Medical Association (AVMA)","license":[{"start":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T00:00:00Z","timestamp":1788998400000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2026,9,10]]},"abstract":"Abstract<\/jats:title>\n \n Objective<\/jats:title>\n To determine the prioritization of shelter animals for sterilization surgery based on length of stay (LOS), when animals must be sterilized before adoption but capacity constraints necessitate deferral.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n This mathematical modeling study defines optimal policy as prioritizing animals whose deferral would have the largest adverse impact on LOS. It derives closed-form expressions for that impact dependent on each animal\u2019s baseline (sterilized) expected LOS, adopter aversion to waiting for surgery, and deferral duration.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n Analytical derivation shows the LOS impact is monotonic in each animal\u2019s baseline LOS. Monotonicity direction depends on a parameter\n V<\/jats:italic>\n measuring adoption opportunity within the deferral window. The parameter\n V<\/jats:italic>\n equals the fraction of adopters willing to commit before sterilization multiplied by the duration of the deferral. An existing guideline prioritizing fast-track animals, which have shorter baseline LOS, is confirmed when\n V<\/jats:italic>\n > 1. This effect is concentrated at low to medium baseline LOS (but flattens above 20 days). When\n V<\/jats:italic>\n = 1, the impact becomes independent of the animal\u2019s baseline LOS. When\n V<\/jats:italic>\n < 1, animals with longer baseline LOS should be prioritized, but this preference is weak.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n \n In practice, shelters should prioritize animals with lower baseline LOS when\n V<\/jats:italic>\n substantially exceeds 1, and there are candidates with low to medium LOS. In the remaining cases, the effect is weak (including\n V<\/jats:italic>\n < 1 when the direction changes), and shelters may rely on other considerations.\n <\/jats:p>\n <\/jats:sec>\n \n Clinical Relevance<\/jats:title>\n These findings provide a quantitative basis for allocating limited shelter resources toward reducing LOS and shelter census, in the interest of maintaining and improving care.<\/jats:p>\n <\/jats:sec>","DOI":"10.2460\/ajvr.26.06.0270","type":"journal-article","created":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T17:29:28Z","timestamp":1789061368000},"page":"1-9","source":"Crossref","is-referenced-by-count":0,"title":["Guidelines for the prioritization of adoptable shelter animals for sterilization to reduce average length of stay: a mathematical model"],"prefix":"10.2460","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-9896-2761","authenticated-orcid":true,"given":"Michael Loizos","family":"Mavrovouniotis","sequence":"first","affiliation":[{"name":"Social Compassion in Legislation, Laguna Beach, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1272","reference":[{"key":"B1","series-title":"Vet J","first-page":"15","article-title":"An observational study of the relationship between capacity for care as an animal shelter management model and cat health, adoption and death in three animal shelters","author":"Karsten CL","year":"2017","unstructured":"Karsten CL, Wagner DC, Kass PH, Hurley KF. An observational study of the relationship between capacity for care as an animal shelter management model and cat health, adoption and death in three animal shelters. Vet J. 2017;227:15\u201322. doi:10.1016\/j.tvjl.2017.08.003"},{"key":"B2","series-title":"Prev Vet Med","first-page":"44","article-title":"Risk factors affecting length of stay of cats in an animal shelter: a case study at the Guelph Humane Society, 2011\u20132016","author":"Janke N","year":"2017","unstructured":"Janke N, Berke O, Flockhart T, Bateman S, Coe JB. Risk factors affecting length of stay of cats in an animal shelter: a case study at the Guelph Humane Society, 2011\u20132016. Prev Vet Med. 2017;148:44\u201348. doi:10.1016\/j.prevetmed.2017.10.007"},{"key":"B3","article-title":"Reduce length of stay","year":"2025","unstructured":"Reduce length of stay. Koret Shelter Medicine Program. May 21, 2025. Accessed September 23, 2025. https:\/\/www.sheltermedicine.com\/library\/resources\/length-of-stay-los"},{"key":"B4","series-title":"J Shelter Med Comm Anim Health","first-page":"S1","article-title":"The guidelines for standards of care in animal shelters: second edition","year":"2022","unstructured":"Association of Shelter Veterinarians. The guidelines for standards of care in animal shelters: second edition. J Shelter Med Comm Anim Health. 2022;1:S1. doi:10.56771\/ASVguidelines.2022"},{"issue":"1","key":"B5","series-title":"J Appl Anim Welf Sci","first-page":"2","article-title":"Effects of phenotypic characteristics on the length of stay of dogs at two no kill animal shelters","volume":"16","author":"Brown WP","year":"2013","unstructured":"Brown WP, Davidson JP, Zuefle ME. Effects of phenotypic characteristics on the length of stay of dogs at two no kill animal shelters. J Appl Anim Welf Sci. 2013;16(1):2\u201318. doi:10.1080\/10888705.2013.740967"},{"issue":"4","key":"B6","series-title":"J Appl Anim Welf Sci","first-page":"375","article-title":"Factors influencing time to adoption for dogs in a provincial shelter system in Canada","volume":"21","author":"Kay A","year":"2018","unstructured":"Kay A, Coe JB, Young I, Pearl D. Factors influencing time to adoption for dogs in a provincial shelter system in Canada. J Appl Anim Welf Sci. 2018;21(4):375\u2013388. doi:10.1080\/10888705.2018.1436917"},{"issue":"1","key":"B7","series-title":"BMC Vet Res","first-page":"70","article-title":"Increasing adoption rates at animal shelters: a two-phase approach to predict length of stay and optimal shelter allocation","volume":"17","author":"Bradley J","year":"2021","unstructured":"Bradley J, Rajendran S. Increasing adoption rates at animal shelters: a two-phase approach to predict length of stay and optimal shelter allocation. BMC Vet Res. 2021;17(1):70. doi:10.1186\/s12917-020-02728-2"},{"issue":"8","key":"B8","series-title":"Animals","first-page":"1158","article-title":"Marketing of slow-track rather than fast-track animals reduces mean length of stay and animal shelter census count: a theoretical study","volume":"16","author":"Mavrovouniotis ML","year":"2026","unstructured":"Mavrovouniotis ML. Marketing of slow-track rather than fast-track animals reduces mean length of stay and animal shelter census count: a theoretical study. Animals. 2026;16(8):1158. doi:10.3390\/ani16081158"},{"key":"B9","article-title":"Length of stay (LOS)","year":"2025","unstructured":"Length of stay (LOS). Shelter Medicine and Community Engaged Care. May 21, 2025. Accessed August 15, 2025. https:\/\/sheltermedicine.wisc.edu\/library\/resources\/length-of-stay-los"},{"key":"B10","article-title":"Play the length-of-stay game","author":"Newbury S","year":"2012","unstructured":"Newbury S. Play the length-of-stay game. American Society for the Prevention of Cruelty to Animals; 2012. Accessed October 2, 2025. https:\/\/www.aspcapro.org\/sites\/default\/files\/aspca_webinar_slides_Play-the-Length-of-Stay-Game.pdf"},{"issue":"1","key":"B11","series-title":"Eur J Oper Res","first-page":"299","article-title":"The impacts of mergers, capacity expansion and adoptions on animal shelter performance: a queuing analysis","volume":"292","author":"Turken N","year":"2021","unstructured":"Turken N, Carrillo JE, Paul A. The impacts of mergers, capacity expansion and adoptions on animal shelter performance: a queuing analysis. Eur J Oper Res. 2021;292(1):299\u2013310. doi:10.1016\/j.ejor.2020.10.022"},{"key":"B12","series-title":"Social Science Research Network","article-title":"Saving lives in animal shelters: strategic time allocation under capacity constraints","author":"Chen QK","year":"2025","unstructured":"Chen QK, Haruvy E, Katok E. 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