Dreams about childhood homes often represent nostalgia and a longing for the past. Since your childhood home no longer exists, it may signify your desire to reconnect with your roots or explore unresolved feelings from your upbringing.

The presence of your deceased dog in the dream could symbolize loyalty, companionship, or a connection to your past. Dogs often represent unconditional love and support, so seeing your old dog may tap into fond memories or emotions related to that bond.

The frustration of not finding the leash suggests feelings of being unprepared or struggling to manage responsibilities in your current life. It may indicate a fear of losing control or feeling constrained by obligations, especially as you navigate a relationship with your girlfriend.

Rummaging through the house and discovering the box of leashes can represent the search for tools or resources to help you handle your current situation. It might also suggest that you have everything you need within you, even if it feels chaotic at times.

Overall, this dream could be urging you to reflect on your past, acknowledge your feelings about it, and consider how those experiences shape your current relationships and responsibilities. It might be helpful to think about any unresolved issues or memories that may need your attention.