You're creating a false dichotomy. Animals swallowing things, being hit by vehicles, attacked by other animals, jumping from 8 story buildings (and living), and so on all cause similar groups of internal injuries - often life threatening. Yes it requires expertise and work to treat them - that's exactly what the job of a vet is. It's not like you go to a vet in the developing world with a puppy suffering severe internal injuries, from whatever reason, and they just shrug and ask if you want to euthanize.

Quite the opposite I expect you'd see dramatically less euthanasia in the developing world (though a quick search unsurprisingly turned up very little in the way of data). But I think the logic should be clear enough. Pets make everybody's lives better and more enjoyable, but very few people could afford to even think about dropping $10,000 on a puppy. Those prices are just a fast-track to mass euthanasia and depressed vets.