本文嘗試探討處理流浪動物的最適經濟政策。我們建構了一個 兩階段的賽局，用以刻劃主管機關、寵物店和消費者之間的互動。 尤其，一個簡單的Hotelling 模型可用來將購買與領養寵物者的行為 內生化。我們的結果顯示，當社會福利的極大化是目標且寵物市場 為不完全競爭時，主管機關可以對寵物的購買者課稅或進行補貼。 另一方面，當寵物市場為完全競爭時，主管機關應該對購買寵物者 課稅。相對地，當流浪動物數目的極小化是目標時，對寵物的購買 者課稅是主管機關的最佳選擇。無論寵物的飼養成本和流浪動物造 成的環境代價是線性的或二次式的函數型態，也無論寵物市場為完 全或不完全競爭，這個結果都成立。

This paper investigates optimal economic policies, that deal with stray animals. We construct a two-stage game to characterize the interactions among the regulator, pet shops, and consumers. In particular, we employ a simple Hotelling (1929) model to endogenize the behaviors of dog/cat purchasers and adopters and show that the regulator may tax or subsidize pet-animal buyers if it aims to maximize social welfare in an imperfectly competitive pet-animal market. On the other hand, taxing pet-animal buyers is the regulator’s best choice in a perfectly competitive pet-animal market. These results hold under both linear and quadratic breeding-cost and strays’ environmental-damage functions. By contrast, when the regulator is targeting to minimize the number of stray animals, taxing dog/cat buyers is the best choice. This outcome holds whether the pet-animal market is perfectly or imperfectly competitive and whether the breeding-cost and strays’ environmental-damage functions are linear or quadratic.