Dog is Barking in front of mirror

dog sees in the mirror might be puzzling. Having said that, not all dogs react to their reflections in the mirror the same way. Some dogs, especially puppies often treat the image as another dog and start reacting to it. They may bark at the image, sometime bow down and invite the other pup in the mirror to play.

This is almost the same as how they would react if they saw another real life dog in front of them. There are others that totally ignore the image. Even with the pups that are initially attracted to the mirror image, over a period of time, realise that the reflection in the mirror is of no consequence and start ignoring it.