So I read it and thought oh I read that wrong what the hell is a horse-flipper how would you do that?
Then I read the rest of the question and was like oh wow I was right the first time but also still wrong because I thought they meant the verb instead of the noun.
Well...spit... growing up on the ranch we had between 13 to 18 horses around all the time. Everything from Arabians to some workhorses.
Now we only shoed them in late summer for the fall when we were working cattle.
Now swimming is an interesting topic. During the hot days in the summer we would hop on a few hoses bareback and race across in the ponds.
You would think the massive workhorses with their oversized hooves would win. Poweful, strong animals with big flippers on the bottom. Unfortunately they were the slowest in the water. They were stiff and inflexible, dumb and slow. They tended to swim a few feet, decide it was too much work, turn around and find some nice grass to eat.
Now the Arabians with the smaller stature and dainty little hooves were by far the fastest in the water. The fastest was horse named ugly. He was a swayed back ill tempered little guy with a massive chip on his shoulder. He just had to be first everywhere. He was almost as vicious as the Spawn of Satan aka "Shetland pony". Now Spawn of Satan didn't like the water because brimstone and water don't go together so we never got him to swim.
What's curious is after they were shod and their hoofs trimmed down, they all seemed a wee bit faster. I guess the smaller hoof works better for their swimming mechanism.
Edit: Turns out, the above farm-life comment is a fabricated fantasy tale.
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Thanks for sharing your lived experience. Your characterisations of each horse gave me a good laugh.
That is very interesting that they would be quicker after being shod. Not sure why that would be. Less apprehensive of kicking something underwater perhaps.
Flippers wouldn't help really given how horses actually swim, they kind of kick back with each of they're legs in a sequence similar to a trot. Their hooves already have a bit of a hollow which likely helps with swimming.
Honestly though horses are pretty good swimmers, because they have huge lungs which helps them stay afloat with ease