is my roommate neglecting his dog?

I believe my roommate is neglecting his dog. He completely disagrees with me, and gets angry and ends the conversation whenever I bring it up to him.

Does this sound like neglect?:

A normal day for my roommate is to go to school until the late afternoon, come home and watch TV for a few hours or do homework, and then he spends his whole night out at bars until 3-4 am. The bar action goes on I would say about 5-6 nights out of the week.

This dog is a pitbull mix, and about a year and a half old. I have watched this dog grow up ever since he was a puppy, and I am pretty sure my roommate has been feeding his dog the same gross dry food his whole life. That seems cruel enough to me...

On top of it, he walks him about once every 2 weeks, and only lets him go in our small back yard to go potty a few times a day. The dog usually goes around 9-10 pm and then my roommate makes him wait until 11 am to go again. Again, this seems pretty cruel.

I walk the dog more than he does, and I actually have a job, and am trying to finish my physics degree. Yet he claims he is too busy to walk him...

I constantly find the dogs water bowl empty. I think I fill it once every day or two.

The dog has had an ear infection for the better part of the last 6 months. My roommate sparingly puts ointment in it.

If you think this is abuse, let me know, and if you have any advice on how to approach the situation let me know too please. I feel guilty about this dog, and he's not even mine.