Another option I haven't seen mentioned here or in any of the other dog/pet threads on MMM is to just NOT take pets to the vet unless they are suffering and need to be euthanized. If you start out with a hardy, mixed-breed dog or cat and feed them good, healthy food, they really shouldn't need to go to the vet for check ups, vaccinations, etc. With a little research it's possible to learn how you can provide for 99% of your pets' healthcare needs yourself. You don't need to hire a professional to do it for you. It seems very Mustachian to me to DIY.
Over the past 20 years or so my family and I have had 2 dogs, 3 cats, a dozen or so cows, hundreds of sheep and thousands of chickens, and we haven't paid more than a few hundred dollars in vet bills, total, and that was mostly in the beginning when we used to take our cats and dogs in to see the vet for their annual physicals. The past ten years or so we have spent almost nothing on our animals' healthcare, other than buying dewormers, which we administer ourselves.
Around 10 years ago, our 9 year old purebred German Shepherd developed problems with her hips. Our vet recommended that we give her steroids, morphine, and some kind of operation. When the dog could no longer walk on her own, we opted, instead, for a $30 shot of something that knocked the dog out and put her out of her misery. I held my dog on my lap while the vet injected the drugs, and she went limp in my arms about 10 seconds after he pushed the plunger down on the syringe. To me it seemed like a pretty peaceful, painless way to go. Could we have kept out Shepherd around longer by letting the vets give her more healthcare? Probably, but why?
Two of our 3 cats died at 14-15 years old in the past year. One developed cancer on her ear. The vet wanted to do an operation and remove the cat's ear. Instead, we opted to bring the cat home and just let her die naturally. Until the day she died, she still could walk around and eat and she loved to sit in our laps and be petted. One day, she disappeared, and we found her dead under a pile of cardboard boxes on our back porch. We built a big fire in one of our pastures and cremated the cat's body, drank some beers and said goodbye to our friend. The other cat died, we think, when 2 stray dogs managed to squeeze around/under our gate. I chased the dogs out, and later that day or the next day we found our cat's dead body underneath our house. She didn't have any marks on her, so we don't know if the dogs bit her or if maybe she had a heart attack?
IMHO, it's possible to have pets, care for them well, love them, yet almost never take them to the vet. I realize this is a minority opinion here, but it's something that I know is possible, because we have been doing it for the past 20 years. One of the two dogs we've owned is still alive. She's a mixed breed, super healthy dog, that is 14+ years old now. She hasn't been to see a vet in YEARS, and she's fine. Our cat is also around 14 years old, and he has, as far as I can remember, never been to see a vet except when he was young and we took him to get neutered. We deworm him, and that's it. He eats about 1/2 cup of food per day. If you provide your own healthcare for your animals, pet ownership can be much, much cheaper than if you hire everything out to the professionals.