Icelandic Horse Connection

Icelandic Horse Size of Stomach and Intestines

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In the book "More Joy With Icelandics", in an interview with Rikke Schultz, DVM, Sweden, it states:

"Studies have shown that the forepart of the digestive tract, stomach and small intestine, or an Icelandic is considerably smaller than in other light horse breeds and the rear part is considerably larger. The volume of the stomach is only 2% of the total digestive tract in Icelandics. In other breeds it is 9%. Foreign data also shows that the large intestine makes up 61% of the total volume of the digestive tract in other horses. In Icelandics this proportion is 71.8%. An American study showed that in other breeds the length of the digestive tract measures 21.78 meters and in the Icelandics the large intestine was 1.23 meters longer."

We have done some searching to determine if this is fact or fiction.

First, we asked other pony owners if they knew of any differences in the intestines and stomach of ponies versus that of horses.

Here are some of the answers that we received:

From a Vet:

As far as I know the ponies and horses are relatively the same. I have not heard nor have I seen any differences, I've done colic surgeries on both and can't say there was and difference. All equids have small stomachs and no gall bladder because their evolution is as a grazing animal. Therefore they are programed to eat many small meals and have no need for a large stomach. Their ceacum and colon on the other hand is very large to accommodate the break down of grasses. Hope this is clear and helps.

Another vet:

No difference according to my husband (a horse vet), who has done colic surgery on everything from minis on up to big old draft horses. Ed says "We used ponies in vet school to learn how to do colic surgery, etc., since they were proportionately smaller overall but their intestines were otherwise perfect replicas of those of horses."

Anatomically speaking there is no significant difference between a pony and a horse of similar size. Obviously large horses have larger intestines and small one have smaller ones. But there is no difference in proportion between a pony and a horse, other than those associated with the size differences. Some ponies can have different metabolisms from highly bred horses such as TBs.

He said he's never done colic surgery on an Icelandic. . . but there should be no reason they are different. . . If you come across a reference that says otherwise I'd love to see it!! It could be another one of those "myths" about horse breeds that is handed down as gospel, even though it has never actually been proven scientifically! Even though Icelandics are considered an old purebred, they originally came from a combination of Scandinavian stock plus stock from British Isles. There are some traits Icelandics have that are common with Fells.

While the overall anatomy of the gut may be the same, it does not mean that this or that breed is not better adapted for different forages. Eg., with different enzymes in gut to digest certain sugars/proteins, etc. You can also see the same kind of thing in humans as far as enzymes - eg., certain ethnic groups have poor ability to digest certain things (eg., Asians/Africans tend to have lactase deficiency - something like more than 90%).

Or different jaw/tooth structure - with some breeds being built to be more efficient at grinding course roughage. A pony with a deep, curved mandible, with long, deep crowns, and incisors angled to "cut" rather than tear, are very efficient in grinding their food. Those with flat mandibles with short crowns are less so.

Dr. Deb Bennet and also Eyjólfur (Jolle) Isólfsson (Head riding teacher at Holar College) were asked. Dr. Deb indicated that there are no differences between pony and horse intestines and stomachs. Jolle was less definite in his answer, but didn't think there would be a difference.

Rikke indicated that the source of her information was one of her late professors from vet school, who was very interested in this, and that she would try to find out more.

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