What should I do about my dog situation?

I dated this ex for over a year, two years ago. We adopted a dog from the shelter while dating. He lived with me until my Dad got tired of his shedding and made me give him to the ex. I used to see the dog a lot while we were still dating but that changed obviously when we broke up. I got to see him every two weeks, then it became every month, and then it became whenever I asked to see him and we looked at our schedules. At some point he got a new girlfriend and he actually blocked me because his new girlfriend felt insecure about me. I didn’t find out until I tried asking to see the dog. It wasn’t until they stopped dating that he told me what happened. Now, I ask to see the dog and we try to work around our schedules but he takes hours/days to reply. He posts and uses social media but never replies so sometimes I have to text him again to confirm/ask. At this point I’m fed up with his lack of communication and respect. I payed for the adoption fee and have loved the dog since day one and never wanted to get rid of him. I thought it’d be fair to at least get to see him once a while but it’s become such a hassle because of my ex. How should I approach the ex about how I’m feeling? Should I even do anything?