This study of dogs and socialized cats entering and leaving Danish shelters is the first such study undertaken in a northern-European country. Based on our findings and the literature, we aim to answer two questions: i) How do the numbers of dogs and cats taken in by shelters compare with the size of the Danish dog and cat populations, and to what extent can rehoming from shelters serve as a means of supplying dogs and cats in Denmark? ii) What explains changes in the numbers of animals taken in, and the outcomes for dogs and cats, over the years studied?