Friend obsessed with dog

I have a friend who is obsessed with his dog. The dog is nice enough but he's 14. The friend takes the dog to the vet often and the dog currently is taking 9 pills a day. Other than his dog obsession this man has been a great friend. He's funny and smart, and has been responsible and kind. The dog developed a slight cough at the end of November. The friend has gone into hibernation with the dog ever since. He is so worried about the dog he has not spoken to anyone. The dog, BTW, is active, he's posting pictures of the dog on Facebook. This friend normally is very communicative. The friend is talking to me on FB publicly but he has not come out of his house. I have not asked about the dog, I'm a little irritated that an ever-so-slightly-under-the-weather dog was enough to not only temporarily halt our friendship but also halted his friendship with everyone else. The friend thinks he is some sort of hero for being so obsessive about his dog. Right now I am practicing avoidance which isn't changing anything. Should I say something? What should I say?

Thank you for the response Susiedqq. My friend is gay and has a cohabitating partner, they are not married. The partner is very busy with his job, his school and his large number of friends. My friend dislikes how much time his partner spends away from him. He also has a sister who he talks to occasionally. We were best of friends that saw each other every other day, but we also have other friends we all spend time together. Our friend group is wondering what is up with our friend. His excuse is the dog. I will take your advice and just ask to meet, see what he does. I really don't want to spend all our time hearing him complain about the dog because that was what he was doing all November until he disappeared. The dog isn't that sick, or the dog isn't sick any more I bet. I'm really busy right now, and then I go to my mother's house for Christmas. Maybe I will wait until after the holidays simply because I might be able to be less irritated by then and more relaxed. I'll provide an update once we meet and see how things go. :-@

I guess I was a bit wrong about the dog. He died, or my friend put him down on Christmas Eve. His partner put up a post on Facebook yesterday. So I bought a sympathy card and dropped it off in the mail slot figuring I didn't want to interrupt the grieving. An hour later I got a knock on the door and it was my friend who was bringing me a Christmas gift. Hey, long time no see! So I invited him in and we talked a bit about the dog, he was low but in okay spirits given the situation. During the conversation he apologized for not visiting or contacting me (and everyone else for that matter). I asked what his plan is for the future since he had devoted his last 4 years to caring for his dog. He said he didn't know, and he was aware that he was going to have much more time available. I told him that sitting in the house watching TV until he died was probably a really bad idea, and he agreed. He said that I should come around now. Hopefully, this is resolved. Thanks for the help!