There are questions on here about getting married, having kids, and other major time commitments during graduate school. But one thing that I haven't seen posted -- but that I've seen come up with some frequency (at least in the US) -- is concerning people getting pets during their PhD. Yea, I know certain pets (e.g. fish and reptiles) take less time to care for than others (e.g. cats and dogs), but I'm specifically wondering about what to consider in the latter case.
Pro: Pursuing a PhD can be a very lonely process, so having some companionship can be worthwhile and perhaps even lead to increased focus and productivity.
Con: Cost and time commitment, particularly early on with a pet.
What are other things to consider in getting a pet during the PhD? Does the timing make a big difference? That is, should I wait until I'm ABD, or should I get one over a summer?
Does having a companion, like a dog, for example, often help students' productivity when they were otherwise adrift in isolation?
Also, I'd be interested to hear from a faculty perspective as to whether it's ill-advised to get a pet during the PhD. I assume most don't care as long as the student stays productive, but I'm curious if there are any anecdotes that support either the pro or con I listed above. Same goes for anyone who got a pet during grad school.
NOTE: The help center explicitly states that questions pertaining to "Life as a graduate student, postdoctoral researcher, university professor..." are on topic (emphasis added). Thus, this question appears to be fully within the stated guidelines.
I'm going to presume in my answer you're looking to stay in academia post-Ph.D.
One of the biggest concerns you're going to have isn't now, but after the Ph.D. Consider if you get a super playful mega cuddlebug kissing dog, there are many places with ignorant breed-specific legislation that would mean you couldn't bring your dog with you.
Unlike in other fields where you probably have a good idea (or decent say in the matter) of where you'll be living at, jobs in academia are scarce, and if you're only offered a job in, say, Denver which bans the aforementioned nanny dogs, are you willing to leave your dog behind to advance your career?
If you're in a field that may require a lot of traveling (public health, foreign languages, anthropology, ecology, marine bio, etc), I would absolutely not recommend getting one unless you have someone that you can consistently and always count on to be willing to watch your animal for extended periods of time. Let's face it, you're not going to be able to afford boarding on a GTA stipend. OTOH, if you're needing to be in the same on-campus lab virtually all year, that might not be a concern at all.
Lastly, consider something else: fostering. You get all the benefits of pet ownership without the long-term complications (unless you become a decide to become a foster failure and decide to adopt). You can also often workout with the foster coordinator to give you dog/cats that are a year or two or older to reduce the initial time commitment because even if not house trained, they can hold it for a work day.