I love pets, I even have two cats right now and I grew up with dogs and cats. One thing I can definitely say about pets is that all they do is give unconditional love. I can see why anyone would want a dog or cat or some other type of pet while they are at college. Sometimes having something that greets you every day can help alleviate the stress of being on your own for the first time and navigating the life of a college student.
If you are struggling financially I would have to say don't get a pet. They are expensive. If you forget about food (which is a constant expense) and accessories (like collars, leashes, and toys) you still need to consider the vet. Although there are ways of getting reduced priced vaccinations the vet bills can be very hefty. Some people invest in pet insurance to offset those expensive bills, but if you add that cost into the monthly cost to feed and take care of your dog or cat the cost can be prohibitive for students struggling to pay rent and tuition.
What ends up happening to these poor animals is that students get them, realize that they can't afford to (or aren't allowed to) keep them and abandon the poor animals. Where I live there is a large roaming cat population because irresponsible students (who probably had good intentions at the start) would do this. With a large population of animals in shelters already (due to the bad economy) please consider what you are capable of taking doing both financially and with your obligations.
It will only be four to six years before you will be done with school and most likely will be able to afford a pet. If you simply can't be away from animals for that long consider volunteering at an animal shelter, or become a dog walker/ pet sitter. This way you get to spend time with animals in a responsible and caring way.