“I challenge you to every day to improve your powers of observation,” began Ric Redden, DVM, founder of the International Equine Podiatry Center in Versailles, Ky., during the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas. “Believe half of what you see and everything you understand.”
Redden explained his methods for evaluating foot flight and limb alignment in horses to the veterinarians in attendance. “This approach is beneficial for assessing horses of any age, from diagnosing limb deformities in foals to identifying potential high-risk factors in prepurchase exams of adult individuals,” he said. “This methodical protocol allows us to better understand variations in distance and structural angles that fall within the range of normal, as well as alterations that are not compatible with soundness. Using a systematic, methodical approach for every exam offers a useful means of enhancing our ability to record small details that may otherwise be overlooked.”
Typically Redden begins his examination by watching a horse walk away from him and toward him repeatedly, as well as assessing the standing horse. As he observes the horse, he envisions imaginary dots on each joint and a few other locations to evaluate how the joints and limb align. For example, he noted, in a horse with bowed forelegs, knees will appear bowed to the outside (away from the midline) when viewed from the front and compared to the area of hocks and heels on the hind limbs.
When viewing the horse from the front, Redden said to assign imaginary dots in the following seven places:
- Center of toe
- Center of coronary band
- Center of fetlock
- Center of the proximal (upper) cannon (note this dot will be superimposed over Dot 5 unless axial deformity is present--more on this in a moment)
- Center of the most distal (lower) aspect of the carpus (knee)
- Center of the distal radius at the level of the physeal (growth) plate
- Most proximal point on the forearm. A small swirl of hair is normally located at the top and centerline of the radius.
While observing the dots, visualize imaginary lines between them and note any deviations of the lines (which might indicate potential for unsoundnesses--more on this in am moment), Redden instructed.
“Have the handler keep the horse’s nose as straight as possible because the digits follow the nose,” he advised. “Astute handlers can hide a lot by where they put the nose when the horse is moving. When observing foals, having someone walk the mare along a wall or fence offers a reasonable means of assessing the foal as he travels beside the mare. Focus on foot flight and the landing phase.
“Also, watch the air space under the foot; if you have a shadow, look at its shape before the foot lands (an asymmetrical shadow shows you that the foot isn’t landing flat),” he added.
“Next, imagine an imaginary laser or arrow centered on each dot, passing squarely through it on the sagittal plane (to show which way that joint or bone is facing),” he went on. “Observing these imaginary lines is a reliable, consistent method for identifying planes of deviation that can and often do occur between major joints. Using the dot system and observing the sagittal plane helps train the eye for details that may otherwise be missed.”
He went on to describe several types of limb deformities, their implications for soundness, and treatment principles:
- Angular (valgus/varus, where the lower limb deviates outward or inward as you go down the leg)
- Axial (inward or outward shift of knee/hock joint surface, such as an offset knee)
- Rotational (outward rotation of the limb generally in front limbs, originating in the shoulder)
- Spiral (inward “twist” of the cannon bone as you go down the leg, resulting in an inwardly rotated lower carpus or knee and a toed-in appearance of the fetlock, pastern, and hoof)
“We must always be mindful of the natural range of anatomical features that is responsible for overall limb conformation, foot flight, and land/load patterns, as well as the limits of the healthy range,” he concluded. “Many foals have multifaceted deformities; some are compatible with future soundness, while others are not.”
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.