Can anyone tell me, and provide a resource, if a foal's legs grow longer after they're born? I read somewhere that their legs are as long as they will ever get, but can't find that information anywhere. I have read "The Ranger Piece" by Dr Deb Bennett, several times over, and while she does address the cartilege in each joint, the leg length topic doesn't come up in her report (highly recommended reading for everyone involved with horses, btw. Proof positive why no horse should be made to carry a person until at least five years of age). Back to my original question, I know it's a ridiculous question, because no one agrees with me, but I can't find any answers regarding it either way. All knowledgable responses, with resources, research data, etc, is appreciated, thanks.
No, their legs are not as long as they will be at birth The bones continue to grow for a couple of years, stopping from the bottom up. For example, the growth plates at the knees don't finish growing until around age 3, give or take.
This The Horse article says that pasterns and cannon bones are just about adult length by around 2 months. A % I recall hearing is they are 90% of their adult length at birth, but of course, that doesn't include any unfolding, and for sure doesn't include circumference.
Dr Deb is a bit too conservative. I totally get her point, but there is scientific proof that proper load bearing work while bones are developing has a positive effect on their long-term health.
______________________________ The CoTH CYA - please consult w/your veterinarian under any and all circumstances. - ET
to me/my observations.....the cannons are done at 12 months (there is a reason you don't string test a horse for mature ht before 12 months), the upper arm at about 3 and pretty much height you get after that is body and withers. So no...they are not their adult lenght at birth.
The process of converting the growth plates to bone goes from the bottom of the animal up. In other words, the lower down toward the hoofs you look, the earlier the growth plates will have fused; and the higher up toward the animal's back you look, the later. The growth plate at the top of the coffin bone (the most distal bone of the limb) is fused at birth. What that means is that the coffin bones get no taller after birth (they get much larger around, though, by another mechanism). That's the first one. In
order after that:
* Short pastern - top and bottom between birth and 6 months.
* Long pastern - top and bottom between 6 months and one year.
* Cannon bone - top and bottom between 8 months and 1.5 years
* Small bones of the knee - top and bottom of each, between 1.5 and 2.5 years
* Bottom of radius-ulna - between 2 and 2.5 years
* Weight-bearing portion of glenoid notch at top of radius – between 2.5 and 3 years
* Humerus - top and bottom, between 3 and 3.5 years
* Scapula - glenoid or bottom (weight-bearing) portion – between 3.5 and 4 years
* Hindlimb - lower portions same as forelimb
* Hock - this joint is "late" for as low down as it is; growth plates on the tibial and fibular tarsals don't fuse until the animal is four (so the hocks are a known "weak point" - even the 18th-century literature warns against driving young horses in plow or other deep or sticky footing, or jumping them up into a heavy load, for danger of spraining their hocks).
* Tibia - top and bottom, between 3 and 3.5 years
* Femur - bottom, between 3 and 3.5 years; neck, between 2.5 and 3 years; major and 3rd trochanters, between 2.5 and 3 years
* Pelvis - growth plates on the points of hip, peak of croup (tubera sacrale), and points of buttock (tuber ischii), between 3 and 4 years.