Lets say I’m on Mackinac Island and I have a heart attack. Am I sent to a hospital on a hors-drawn carriage?
I believe they have official service vehicles, and an ambulance would definitely count as a service vehicle.
The real question you should be asking is: “Is the hospital on the mainland?”
Wikipedia claim that the only official service vehicle is a snowmobile.
(bolding mine)
I just looked through some of the tourist sites, and I haven’t found explicit mention of ambulances or hospitals, but I’d be very surprised if there wasn’t at least a clinic, given the island’s isolation during the winter.
I have been to Mackinac Island three or four times. The last time I was there, I heard from a local guide that there were several Jeeps and trucks for use as service vehicles. This was in 2004.
I remember being taken to a medical clinic to have my wounds cleaned and dressed when I visited the island with my parents, many years ago.
If you are really bad they will send Survival Flight (helicopter/jet med-evac) from University of Michigan Medical Center.
When my parents were on their honey moon there almost 30 years ago, they did have some sort of an emergency vehicle.
That must have been SOME honeymoon! 
On a recent episode of “DIRTY JOBS”, they showed how much work it was to haul away the horse droppings-which are deposited all over the streets of the island.
In summertime, the fragrance (and the flies) must be overwhelming!
So, I’ll take smelly car exhaust over horse crap, any day!
It’s not bad; they’re quick about it, and it takes the flies a long time to get there. And as gross as it sounds, horse dung isn’t all that bad smelling. I grew up in the sticks, though, so maybe I’m just used to it.
the only time you don’t smell “horse” is winter and lilac season.
i thought they could make quite a bit of money selling makinac island fertilizer.
they do have an air field so you can be lifted off island rather quickly.
It doesn’t smell like horse crap. It smells like horse crap and fudge.
This flight is referred to by employees as Death Star.