Negative Plane P3's & Prolapsed Frogs By Gene Ovnicek
There are many subtle lameness issues that are not easily recognized until they become acute at the problem site or become painful in a referred area of the body. Typically foot problems affect more than one area of the upper body. It is quite common with observant owners and equine caretakers, farriers included, to see and recognize stiffness in the rear quarters when lifting and positioning the leg to the rear for examination of the foot, or for trimming and shoeing. Stiffness with normal manipulation should alert you to further investigation of a potential problem. Frequently horses that are reluctant to freely manipulate the hind limb for shoeing or trimming exhibit pain in the back over the loin. They can show discomfort in the hocks and stifles as well. If these symptoms exist, I suggest that a healthcare professional be called upon to help fully and accurately diagnose any structural defects. In many cases of rear leg stiffness and sacroiliac pain, the foot shows consistent features of distortion and malfunction as well. When examining the foot closely from the side (lateral view), there is commonly a crown or arch to the dorsal hoof wall. (Fig. A) This often corresponds with heels that are very unstable and appear to crumble easily under the weight and movement. Along with what seems to be poor heels, the frog is very large and has descended through the shoe to meet the ground. With hoof tester examination, a positive response is common in the sole behind the widest part of the foot, through the heels and occasionally over the frog. Irregardless of the pain response from the hoof testers (painful or pain free), the discomfort that exists when manipulating the limb, the dorsal wall arch and the prolapsed (enlarged) frog are the main indicators that lead to suspicion of a negative P3 plane. (Fig. B) This means that the bottom surface of P3 that is normally elevated slightly more in the rear than in the front (2° - 5°) or in some cases parallel, is actually closer to the ground in the rear of the bone than in the front. The cause of this condition is speculated by many to be a genetic weakness of soft tissue that supports the back half of P3 (ie; digital cushion, lateral cartilage, etc.). As well, one could logically suspect that the situation is created by trying to leave heels tall to achieve pastern alignment to raise the angle. This approach is clearly responsible for an unhealthy under-run heel condition that causes severely curved bars and curved heels that crumble under the weight of the animal. In addition, low level pain, bruising and abscessing are often the result of this practice and seems to validate an unwillingness for the horse to land heel first. The enlarged frog is a natural response by the foot to supply support to the back of P3 when the normal structures are not available to service those duties. Typically in this situation, the frog is very healthy and is level with the ground through the shoe at the end of the shoeing period.
Figure A
Figure B
Treatment Procedure

With a better understanding of the condition and how Mother Nature is involved in the treatment, one can become involved in a complimentary protocol. Allowing a horse to be barefoot is one way of supporting P3 by allowing the frog to fully load, hence fill the area of soft tissue in the rear of the foot beneath the back portion of P3. This works well for some of the cases.

Many feet in moist areas with this condition will only widen when the increased support of the enlarged frog is being compressed within the back of the foot. Only temporary results are seen and in time the condition can return. In these marginal barefoot attempts, the use of shoes and a hard Multi-Purpose plate are the first in a series of treatment procedures.

It is not uncommon for a horse to be uncomfortable standing once the shoe is removed and the heels are trimmed to the level of the live sole. Properly preparing the bars and heels to the Natural Balance standards is necessary for reconstruction of the back of the foot. The discomfort is occasionally experienced temporarily I assure you, but is required to improve the situation. The mistake commonly made by most farriers, myself included, is to not allow the frog to be loaded, hence, exacerbating the condition. It works best if the horse can be left barefoot and housed in a confined area on a flat, firm surface for a period of 24 to 48 hours until the frog is repositioned comfortably within the foot. The original discomfort will disappear within hours.

An aluminum NBS, steel NBS, or EDSS shoes, along with the Multi-Purpose plate works well for the initial application after the 24 to 48 hour adjustment period. An Elite Hind steel shoe is best suited for hind feet applications, along with a Multi-purpose plate. I find that Sole Pack works best as a filler beneath the pad, the reason being is that the frog has to continue to deviate and conform to its new position within the back of the foot. If Impression Material is used on the first shoeing, the frog would be limited in its ability to deform properly and comfortably. The shoe and pad can be secured with as many nails as necessary, including nails used behind the widest part of the foot. A heel first landing is generally seen with the first shoeing, if not immediately, then generally within a few days. If the horse fails to land heel first within a few days, elevation with rails or wedge pads may be necessary to achieve these goals.

With a heel first landing and regular work, much of the back pain and rear leg stiffness is reduced, and in many cases eliminated. Over the next 2 or 3 shoeings at 6 to 8 week intervals, Impression Material and NBS Pads can be used as the next level of treatment.

Additional applications using the Multi-Purpose Plates will be discussed in the next issue of “Natural Hoof Prints.”
Figure C
Figure D
1. Push the frog back up into the foot.

2. Digital Cushion & Lateral Cartilage lift the back of P3 and cause the extensor process to move forward.

3. You can now safely trim the heels back relative to the live sole and place breakover 1/4" ahead of the tip of P3.

4. The bullnose dorsal hoof wall should NOT be rasped. In time the wall will resume a more straight conformation from the coronary band to the toe.

 Post shoeing lateral view with Multi-Purpose plate and Natural Balance Shoe. Over the next few shoeings, the heels will regrow more upright and the bullnose dorsal hoof wall will resume a straighter conformation from top to bottom.
Negative Plane Distal Phalanx (P3) - Lateral View
Prolapsed Frog - Solar View
Prolapsed Frog - Rear View
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