I didn't know how big a spendthrift I was married to (29 years) until she died. After her passing I was able to save over 50% of my income which allowed me to FIRE 3 years earlier than planned. Such a sad way to reach your goals, however things do happen that you can't control.
I have been pet free since I retired early. I am way too active and travel too much to own another dog (or other pet). I have also noticed that my expense savings of not owning a dog pays for a couple of Elderhostel trips each year.
But, if you are a true pet lover go with your gut feelings...
I spent all my flight pay on alcohol as did most of my squardron mates. But I did bank most of my pay raises. When I got off active duty and joined the reserves, I banked 100% of my drill and summer camp pay. That disipline helped me ER sooner