Bone

I will briefly reiterate my points from my previous blog. The system of inspection used is a minor consideration. However, the inspectors need to be in agreement about the ‘’type” that they are inspecting for the system to be successful. The continental warmblood organizations are successful for the simple reason that their ‘vision’ of the horse they are selecting for is uniform regardless of inspector. What you are seeing currently in the Irish Draught breed is the result of the inspectors selecting and passing horses based on their own individual idea of what the ‘Irish Draught type’ is. Until breeders tackle the elephant in the room and come to an agreement about type the breed will continue to flounder.

I am also concerned about bone after reading what the task force recommended. “The task force indicated that nine inches of bone should be a goal for IDs.” This statement is inexplicable to my understanding of bone and its function. To say that nine inches of bone is the goal for IDs is to say that 4 x 4s are the goal for columns in all buildings – from a shed to a skyscraper. 9 inches of bone in a 15.2 hh horse is more than adequate. On larger 16.2 hh or so 9 inches of bone is inadequate.

In a series of articles by Dr. Deb Bennett in Equus magazine, she discussed conformation in detail using photographs, illustrations, table and graphs. The article on proportion, was in the January 2010 issue which is where the gist of the following information was obtained.
Dr. Deb Bennett used an example of a 10 hand pony and a 20 hand heavy draught horse. You will note that the 20 hand draft horse is 2 times the height of the 10 hand pony. Duh you say. The pony weighs in the range of 320 to 350 lbs. Does the 20 hand horse double the weight making him 640 to 700 lbs? Certainly not. The 20 hand horse weighs between 2600 and 2800 lbs. for an eightfold increase in weight.

Dr. Bennett recommends B-T (bone-tendon circumference) measurements of 8 inches per 1000 lbs in a riding horse. This figure is also in line with what the old Quarter horse folks told me many years ago. The 20 hand horse would have 12 inches of bone at the average 1700 lb horse of 6 inches of bone per 1000 lbs. At the recommended B-T measurement o 8 inches of bone per 1000 lbs. in a riding horse, the 20 hand/2000 lb horse would need 16 inches of bone. This B-T figure is impossible to attain.

In studies where actual measurements of horses were taken and graphed, suffice it to say two things. Large horse = large limbs and feet , & bigger horse = less substance. The survey included data about whether the horse was lame or not. The lameness tended to “lie toward the high end of the weight range and toward lower substance. This data suggested that “regardless of a horse’s breed or weight, if his B-T circumference falls below six inches per 1000 pounds, he has an increased chance of experiencing unsoundness.”

Dr. Bennett briefly touched on bone density. She said that density means mass per unit volume. It doesn’t indicate anything about quality of bone. “Abnormally high bone density is a condition called pachyostosis; osteoporosis is its opposite.” In horses of the riding type weight of 900 to 1300 pounds, the normal bone density is about 19 grams per cubic centimeter, with a range from 15 to 22 considered the norm. The findings from the data collected indicated three things.
-Bone density is related to weight not breed.
-The smaller the horse, the greater the chance that bone density will be normal.
-The larger the horse, the lower the bone density is likely to be.

To summarize, Dr Bennett recommends that you select riding horses between 900 and 1300 pounds with B-T measurement equaling about 8 inches of bone per 1000 pounds but no less than 6 inches per 1000 pounds.