What is the biggest difference in early brain development between puppies and kittens?

The biggest difference in early brain development lies in when their eyes open and their critical socialization windows begin. Puppies are born with their eyes closed and typically open them around 10-14 days old, with their critical socialization period starting around 3 weeks and lasting until 16 weeks. Kittens, however, open their eyes earlier, around 7-10 days old, and have a much shorter, more intense critical socialization window from 2 to 7 weeks. For more in-depth information, delve into our comprehensive article on early pet development.