A dog is mans best friend and in dreams signifies your human nature (animal nature). If you disconnect from life you can find yourself dreaming of losing your dog. To dream of a lost dog returning asks you to let your mental guard down and trust your instincts.
If I were you I'd sit down and list the attributes
of your dog that endears him to you.
Then see if you too have these attributes,
or if life has hardened you.
Just a suggestion.