The Wild Horse's Foot

2001 - 14th Annual Bluegrass Laminitis Symposium Notes

The Wild Horse's Foot

Written and presented January 2001 by R.F. (Ric) Redden, DVM

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I envied individuals who had the opportunity to study the feet of wild horses. So in January 2000, I launched a very serious project designed to record the radiographic and gross anatomical data in regard to wild horse feet.


Project goals:


1. Determine if wild horse foals and weanlings develop PIII fractures along the parietal groove that are frequently found inlight breed domestic horses, especially Thoroughbred foals.


2. Develop a range of normal radiographic parameters; horn-lamellar zone, toe - heel angles, sole depth, palmar angle, relationship of the extensor process with the top of the hoof wall and digital breakover.


3. Record the incidence of club feet (all grades) in young and mature horses.


4. Establish a range of normal contrast pattern in the digit using a venogram.


5. Collect a significant number of foot molds for further study.


6. Record angular deformities.


To my knowledge there has been only one radiographic study on live wild horses. (ref. accomplished with a turn table chute).


The first group of horses was gathered just south of Las Vegas four days prior to my examination. Using Ketamine and Rompun to sedate the horses, foot molds were obtained and radiographs taken. Views include lateral, AP, and 65 degree DP views. With the assistance of Dr. Tom Hartgrove and the Bureau of Land Management, we were able to study eight individual cases. All were more than one year old, no pathological lesions were observed, and none presented with club feet or abnormal angular deformities. All were in good flesh, but they appeared thin compared to domestic standards. Regardless, they all seemed healthy and sound, with a superb protective attitude.


The following is a basic summary of the radiographic soft-tissue parameters:


1. Horn - lamellar zone range

(20/20 mm. - 25/25 mm., majority 25/25 mm.).


2. Sole depth (15 mm. average).


3. Palmar angle (zero degrees).


4. Digital breakover distance (zero to 10 mm.).


5. Extensor process/top of hoof wall (ranged from zero to 10 mm.).


6. Toe angles (range 50 to 59 degrees, average 55 degrees).


7. Heel tubule angle (40 degrees).


8. Toe length (hair to breakover)

(range 2 to 2 1/2 inches, average 2 1/4).


9. Horn height in the center of the foot (1 1/2 to 2 inches, average 1 3/4 inch).


10. Foot size (3 3/4 x 4 W/L 4 1/2 x 5).


NOTES OF INTEREST:


This was a moving experience to say the least. Being the first to ever touch the feet of this small herd and to feel the strong message of Mother Nature was very enlightening and a catalyst for my project. I was surprised to find very short hoof capsules, yet all had thick, protective soles. The soles appeared burnished and fused with the frog which was hardly noticeable. There was only a slight mention of a medial - lateral sulcus. The characteristic shape and size of PIII varies considerably from that of most domestic horses. The apex is more blunt and the solar surface is more convex along the wings as viewed from the lateral radiographs. It is smaller in relation to hoof size than seen with the domestic horse.


The palmar angles are basically zero degrees verses three-five degrees for front feet and five to eight degrees for hind feet (ref. Verschooten). The horn - lamellar zones measured 25 mm on most mature horses verses 15 mm for the light breed domestic horse. The endodermal/ectodermal junction measured 7.5 mm from the face of the bone. The horn - lamellar zone was 1 - 1 with all young feet, only those three years or older exhibited the thicker wall characteristics. The front and rear feet all exhibited a similar breakover/heel-load surface. The wall along the ground surface had a very smooth radius that was void of any sharp edges. All feet were worn smooth with no signs of weak walls or broken out horn.


January 11, 2000 Second herd consisting of 1500 horses. This was simply a drive through and walk through examination.

This herd contained 600 yearlings and five newborn foals, with the balance being older horses. Radiographs, venograms, photos, and foot molds taken on 22 cases consisting of:


Two mature mares with foals.

One foal

Seven mature horses.