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Aug. 22nd, 2011 12:39 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
which_chickEverything Equus has to offer on Developing An Eye For the Total Hind Limb, with picture analysis. I'm sure this is stunningly exciting for everyone, so make with the clickiting...
"The main structural factor of the hind limb that determines a horse's athletic aptitude is the length of the segments composing the limb -- both relative proportions and the sum of their individual lengths. The Total Hind Limb Length (THL) is the sum of lengths of line segments representing the femur, gaskin, hind cannon and hind pastern plus the hoof."
Got that? We're comparing THL to "standing hip height", which is the big vertical line mostly drawn "on the horse's hindquarter" in the sample pictures.
For acceptable hq configuration, the article says that THL can be as low as 106 or as high as 109 % of the standing hip height but 108% is "ideal". Percentage of 105 or lower is post-legged; percentage of 110 or more is over-angulated.
The next thing we're looking at is "percent straight" for the angles on the gaskin and hock joints. (Measure the angle of each joint, add 'em up, divide by 360 to get "percent straight".) Ideal is 80%, OK is from 79 to 87.
I used Gimp for all of this (Gnu Image Manipulation Program), on my Ubuntu laptop. Measurements were all in pixels for distance, so I can't compare directly from picture 1 to picture 2, but I can compare *ratios* from picture to picture.
Horse #1: Tin
Horse #2: Nick
Horse #3: Kazam
If you had asked me before I ran this analysis, I would have bet money that Horse #3 had the best hind legs of the bunch. I'm still not sure (post analysis) that he doesn't. However, here's what the numbers showed, and maybe I drew wrong or measured wrong or something. I dunno.
Tin
1068 ball joint to ground
femur 308.6
gaskin 339.5
cannon 333
fetlock to ground 156
sum: 1137.1
1.064 of THL
Angles
stifle 143
hock 150.5
81.5% straight
These numbers are OK but not spectacular. Refer, above... 106-109 is OK for THL ratio. 79-87 is OK for "percent straight". So, y'know, we're good. 108 is "ideal" for the first number. 80 is "ideal" for the second.
Nick
858 px from ball joint to ground
femur 280.5
gaskin 286.3
cannon 244
fetlock to ground 125.9
sum: 936.7
1.09% of THL
angles
stifle 144.67
hock 145.3
ratio 80.5% straight
Kazam
1360 px from hip ball joint to ground
Femur 415.3
gaskin 494.1
cannon 409
fetlock to ground 184
sum: 1502
110.4 %
Angles:
stifle: 130.82
hock: 150
78% straight
The only thing I can figure here is that I have a shitty picture of Kazam... but the article says "relaxed, with weight on all four feet" and claims that it does not matter much else besides that. I dunno.
With these pictures and figures, we can also look at other interesting things, like the difference between distance from point of hip to stifle vs. distance of gaskin, mentioned in passing the other day.
Tin:
Point of hip to stifle: 381
Gaskin: 339.5
Ratio: 1.122
Nick:
Point of hip to stifle 333
Gaskin 286.3
Ratio: 1.163
Kazam
Point of hip to stifle: 498.5
Gaskin: 494.1
Ratio: 1.009
And, y'know, angulation of stifle joint (which we measured in combination with another measure, above, as part of "percentage straight").
Tin: 143
Nick: 144
Kazam: 130
All I can say here is that maybe the picture stance matters a hell of a lot (I can go take another picture of Nick and remeasure to see if that makes a difference...) or I totally have screwed up the maths somewhere. I was hoping that this little exercise would clarify things for me and all it's done is confuse me more. :(
"The main structural factor of the hind limb that determines a horse's athletic aptitude is the length of the segments composing the limb -- both relative proportions and the sum of their individual lengths. The Total Hind Limb Length (THL) is the sum of lengths of line segments representing the femur, gaskin, hind cannon and hind pastern plus the hoof."
Got that? We're comparing THL to "standing hip height", which is the big vertical line mostly drawn "on the horse's hindquarter" in the sample pictures.
For acceptable hq configuration, the article says that THL can be as low as 106 or as high as 109 % of the standing hip height but 108% is "ideal". Percentage of 105 or lower is post-legged; percentage of 110 or more is over-angulated.
The next thing we're looking at is "percent straight" for the angles on the gaskin and hock joints. (Measure the angle of each joint, add 'em up, divide by 360 to get "percent straight".) Ideal is 80%, OK is from 79 to 87.
I used Gimp for all of this (Gnu Image Manipulation Program), on my Ubuntu laptop. Measurements were all in pixels for distance, so I can't compare directly from picture 1 to picture 2, but I can compare *ratios* from picture to picture.
Horse #1: Tin
Horse #2: Nick
Horse #3: Kazam
If you had asked me before I ran this analysis, I would have bet money that Horse #3 had the best hind legs of the bunch. I'm still not sure (post analysis) that he doesn't. However, here's what the numbers showed, and maybe I drew wrong or measured wrong or something. I dunno.
Tin
1068 ball joint to ground
femur 308.6
gaskin 339.5
cannon 333
fetlock to ground 156
sum: 1137.1
1.064 of THL
Angles
stifle 143
hock 150.5
81.5% straight
These numbers are OK but not spectacular. Refer, above... 106-109 is OK for THL ratio. 79-87 is OK for "percent straight". So, y'know, we're good. 108 is "ideal" for the first number. 80 is "ideal" for the second.
Nick
858 px from ball joint to ground
femur 280.5
gaskin 286.3
cannon 244
fetlock to ground 125.9
sum: 936.7
1.09% of THL
angles
stifle 144.67
hock 145.3
ratio 80.5% straight
Kazam
1360 px from hip ball joint to ground
Femur 415.3
gaskin 494.1
cannon 409
fetlock to ground 184
sum: 1502
110.4 %
Angles:
stifle: 130.82
hock: 150
78% straight
The only thing I can figure here is that I have a shitty picture of Kazam... but the article says "relaxed, with weight on all four feet" and claims that it does not matter much else besides that. I dunno.
With these pictures and figures, we can also look at other interesting things, like the difference between distance from point of hip to stifle vs. distance of gaskin, mentioned in passing the other day.
Tin:
Point of hip to stifle: 381
Gaskin: 339.5
Ratio: 1.122
Nick:
Point of hip to stifle 333
Gaskin 286.3
Ratio: 1.163
Kazam
Point of hip to stifle: 498.5
Gaskin: 494.1
Ratio: 1.009
And, y'know, angulation of stifle joint (which we measured in combination with another measure, above, as part of "percentage straight").
Tin: 143
Nick: 144
Kazam: 130
All I can say here is that maybe the picture stance matters a hell of a lot (I can go take another picture of Nick and remeasure to see if that makes a difference...) or I totally have screwed up the maths somewhere. I was hoping that this little exercise would clarify things for me and all it's done is confuse me more. :(
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Date: 2011-08-22 01:19 pm (UTC)In essence, to my eye, horse 2 has the most functional hindend.
Horse 1 looks like it's still growing, but I doubt that hip is going to lengthen enough to fix that overly long thigh/ cannon and straight hock angle, and horse 3, while having a nice hip, shoulder, cannon,(and best feet I think) has too long a thigh which makes the joints work harder and reduces longevity due to wear and tear. Horse 2 appears to be a little cow hocked but that doesn't signify much; a lot might be an issue. I would like a tiny bit more length to 2's pasterns, but again it's less significant than the hip thigh angles.
In short, I don't think it's the stance or the maths.