26 Signs Your Dog Might Be Dying | Molly Jacobson 

She did talk about wanting to stay outside/away from family a lot, so that behavior would be similar to hiding away.

Social isolation and wanting to be outside a lot are the behaviors that sometimes we take as "hiding." We agree, that word definitely describes it, and it feels awful when our dogs hide from us, especially when we are worried they are just about to leave. 😞