Marketing of Slow-Track Rather than Fast-Track Animals Reduces Mean Length of Stay and Animal Shelter Census Count: A Theoretical Study.

Animal shelters operate under capacity constraints in which average length of stay (LOS) determines the number of animals in care and the resources required to maintain humane standards. Shelters commonly distinguish between fast-track animals, which are expected to be adopted quickly, and slow-track animals, which tend to remain longer. Many operational interventions, such as preferential kennel placement or active marketing, are limited resources that must be allocated among these groups. We developed a mathematical framework to evaluate how simple, broadly applicable interventions affect expected LOS as a function of an animal's baseline LOS. We analyzed the impact of marketing interventions with multiplicatively higher adoption odds. We showed analytically that marketing interventions yield larger reductions in expected LOS when applied to slow-track animals. To examine population-level consequences, we constructed a steady-state kennel allocation example and validate the results using Monte Carlo simulation with stochastic intakes and adoptions. Across both analyses, prioritizing slow-track animals for marketing resources minimizes the total in-care census count relative to the opposite strategy. These findings provide a quantitative basis for allocating limited shelter resources. Preferential marketing of slow-track animals helps reduce mean LOS and maintain the in-care census count within capacity.