This thread is great because Dog People 🙂
Boyfriend and I have a 19 month old pit mix (small, 40lbs) that we adopted from the pound when she was a year old. I love the crap out of her but there is NO WAY I would have been mature enough to take care of her when I was an undergrad. I grew up with dogs and my family treats them like family members, but I only recently felt like I was in a place in my life where I could financially and emotionally afford a pup.
There are unforeseen things that happen sometimes, for example about 3 months after we got her she 1. Had horrible diarrhea on the floor while I was in the shower and bf was at work 2.Ate it because she knows we hate finding poop on the floor 3.Vomited it back up all over our belongings.
We laugh about it now.. but at the time there was no amount of lysol and febreeze that could cover the smell. It was horrifying. Normally, she brings so much love, joy, and exercise into our lives, but just last week she got stuck under the deck and we had to pull up some boards and pay the landlord for repairs to get her out. It's not just the day-to-day stuff that's hard/expensive, it's the incidentals.
Also; finding housing. It just basically boxes you out of living with roommates who don't want a dog and out of many many apartments. It helped me to have more pieces of my living arrangement set in place before I added a dog to the mix, but if you are really devoted you can work the other stuff around the dog.
Lastly, cats are easy. For low-maintenance love: cats.