Are horse hearts "too small"?

This is a new one for me.

My father-in-law is a Bible literalist, with the thousands year old earth creation thingy and everything. He’s a great guy and it rarely comes up.

Anyway, the other day, he asked my wife and I, “Did you know a horse’s heart is too small? I’m taking a survey.”

I said, “No.”

He explained the horse hoof mechanism of pumping blood back up the leg and that the heart itself is too small to circulate blood around the entire body. He went no further, but I’d wager a guess that irreducible complexity would have been the next step if we continued.

So, is the heart actually too small for a horse to function without its frogs? If the hooves, and consequently the frogs, were removed, would the horse fail to circulate blood all around its body? How does it circulate when laying down?

Thanks.

Too small for what?

And the connection to the frogs was rather abrupt. (I assume you meant the anatomical feature of a horse’s hoof, rather than the amphibian.)

I’m going to leave the creationist stuff alone. It doesn’t have much visible bearing, other than to perhaps tar your father-in-law as gullible enough to posit such a question.

Unless horses have a serious track-record of dying of congenital cardiac insufficiency, I’d have to say that no, the typical horse’s heart is not too small to support its life.

Frankly, you should point out that a horse with too small of a heart is a terrible design, unworthy of a Creator’s genius. But that sounds like an invitation to open up an entire can of crazy rather than just catching a whiff from a seam leak.

ETA: Overall, this sounds like another stupid “Bumblebees are aerodynamically incapable of flight” thing.

Perhaps the origin of this tale is the fact* that there is a much finer line between a horse’s ability and self-destruction. i.e. a horse might be able to walk fine for 100 miles but then walk 110 and then just drop dead. Whereas a human might be able to walk fine for 20-40 miles, stagger for another 20, and then get exhausted and not be able to move for half a day or so, but would not die percentage-wise compared to horses.

*Although I do not have a cite for this. If anyone does have a cite for something like this I’d appreciate it since it is something I’ve wondered about. (And to tie into the OP, does it have anything to do with heart size?)

Hmmm. I’ve spent all my life around horses and have never heard this one.

Contrary to what you’d expect, the interior of a horse’s hoof is filled with blood vessels, which support the “lamina,” the fibrous tissue that holds the hoof capsule (which contains the coffin bone) to the hoof wall. The frog is a triangular shaped structure on the bottom of the hoof that serves as a shock absorber as the hoof strikes the ground. Even though a horse’s hooves appear very hard and unyielding, they actually flex as weight is placed and removed during travel. Horse shoes interfere with this because the inflexible steel shoe does not let the hoof flex the way it is supposed to. And, yes, that flexion does help pump blood out of the hoof, but I don’t think it’s because the heart is too small. If that was the case, stallbound horses would drop dead from lack of oxygen to the brain.

Its reducible to “wrong”.
The legs of the horse need the “Frog” , due to the head of pressure needed to return blood from the bottom of the leg up to the main part of the body. Human legs do the same thing, but with the lower leg muscles acting on the vein, and the valves in the vein to cause the pressure to direct blood the correct direction.
Should the heart increase more pressure, the arteries and veins would have to be made of tougher stuff.

Flow rate affects the top performance, and some top horses have had unusually large hearts but its very rare for a horse to be turned into a cow by having a small heart.

Summary: They all need the frog for PRESSURE reasons, not flow rate.

I don’t know, because it is a criminal offense for my butcher to sell it in the land of the – never mind. I know how big beef and chicken hearts are.

My first thought as well. Humans’ hearts don’t effectively pump the blood up from our legs through sheer blood pressure, either - muscle movements and valves help to do that.

Seems like the problem is with a person who thinks that the heart is solely responsible for venous return, which is not accurate for more than one species.

I guess I fail to understand the relevance of your FIL being a biblical literalist and his thoughts on horse hearts. Does the bible say somewhere that horses hearts are too small?

So Secretariat was God trying to fix his screw up?

At the time of Secretariat’s death, the veterinarian who performed the necropsy, Dr. Thomas Swerczek, head pathologist at the University of Kentucky, did not weigh Secretariat’s heart, but stated, “We just stood there in stunned silence. We couldn’t believe it. The heart was perfect. There were no problems with it. It was just this huge engine.” Later, Swerczek also performed a necropsy on Sham, who died in 1993. Swerczek did weigh Sham’s heart, and it was 18 pounds (8.2 kg). Based on Sham’s measurement, and having necropsied both horses, he estimated Secretariat’s heart probably weighed 22 pounds (10.0 kg), or about two-and-three-quarters times as large as that of the average horse.

Omar Little: The literalist/creationist would likely look upon this and think they see something that could not evolve out but would need an engineered design.

Well, I said the creationist thing doesn’t come up often, but that wasn’t the best way to put it. He’s super dedicated to proving creation and disproving evolution. He has a website and obsesses on it. It mainly does not come up because I avoid the issue. It feels like a pointless conversation. I am almost positive his statement about horses relates to his website in proving creation.

He’s a small time Ken Ham actually. He probably thinks Ham won the debate against Bill Nye.

And, according to Science, bumblebees cannot fly, but they do! :rolleyes:

A horse can be walked to death in less than 24 hours.

You can’t do that to a mule.

Why is that?

Once upon a time, there was a horse named Secretariat.

The horses we see today are the result of many years of selective breeding. Racehorses for speed, carthorses for strength, ponies to work down mines - you name it. If their hearts are too small - you can surely blame the breeders and neither God nor evolution had a lot to do with it.

They are that much smarter than a horse.
It is very difficult to work a mule to death but you can do that to a horse a lot easier.

I don’t know that much about it, just stuff I have seen, heard & experienced over the years.

Donkeys are used in dangerous places ( riding into canyons etc. ) because they seem to know what they can & can’t do. Maybe a better survival instinct?

Has anyone else seen this horse heart thing connected to creationism?

The heart is responsible for blood pressure in arteries. Is it responsible for blood pressure in veins? My guess is that once the blood goes through capillaries, the effective pressure is minimal, and that except for large veins fairly close to the heart, the heart’s pumping action isn’t significant.

Imagine what giraffe legs need!

If I’m right, even with a bigger and more powerful heart, a horse would still need frogs. My guess is that a horse’s heart is just the right size. Horses with hearts that are too big for the purpose would be less effective at their work and culled out. Those with hearts that are too small would suffer from other ailments and be culled, or cull themselves out by dying before reproducing.

Its a miracle!!

IIRC its bumblebees cannot glide but fly just fine. Lots of membrane winged insects share the same problem.