Ask the Vet: The Foot

Question: My horse is recovering from a lameness and abscess that my vet contributes to a retained sole. I’ve never heard of this before in 40 years of caring for horses. How common is this? What can I do to prevent this from reoccurring?

Answer: A retained sole (also known as false sole) is when a separation occurs between sole layers of the outer hard sole and the inner soft sole; they separate and form a pocket. It’s actually more common than you would think. In my experience, it develops when the horse has a thin sole (<15-20 mm sole depth as seen on a lateral/side view of the hoof) and either a deep bruising/inflammation develops, which separates the outer and inner sole. It most likely occurs from stepping on something hard like a rock, ice-covered pasture or hard arena footing.

The pain can either come from the edges of the pocket, which press on the soft, new sole beneath or from direct pressure of the hard sole on the soft sole as the horse walks. The only way to rid the horse of pain is for your veterinarian to peel out the hard sole with a hoof knife. This gets rid of the pressure/pain from the hard sole and allows the soft sole underneath to become firm. It is imperative that the soft sole underneath be protected during the time it is getting harder so new new bruising occurs. Usually after it matures for 1-2 weeks, I then put a protective pad under the shoe for one shoeing cycle so that the sole cannot be bruised as its growing out.

Question: I have a 5-year-old gelding with a club foot. He had check ligament surgery as a 2-year-old. We are still struggling to get a heel first landing or at least a flat footed landing. The farrier has tried wedge pads, which did not work. He is much better after letting his feet grow, but seems as though the toe was cut too short, causing his knees to buckle. His frog was atrophying so, at my suggestion, we had his shoes pulled. He was definitely headed in the right direction for the first two months as his frog was growing and he was landing flat footed part of the time. Now we have back slid and he is now walking on his toe again. Any thoughts?

Answer: When the club foot does not respond to the check ligament surgery, it can be difficult to manage as an adult. The reasons for this can be several-fold. Firstly, it is possible that the foot, as you suggest, has been trimmed too short. Many farriers and owners want the foot to look normal after trimming. Unfortunately, the foot is anatomically abnormal at this point and should not have the heel trimmed short. Taking off heel to ‘create a more normal angle’ creates tension on the deep digital flexor tendon (DDFT). This creates pain within the foot as the deep is putting tension on the coffin bone, which creates pain in the laminae (attachment to the hoof wall) or small tearing of the laminae. Additionally, if the heel has been trimmed to short, the tension in the heel region decreases the blood supply to the foot, which slows sole growth. This means that, in addition to pain in the laminae and heel region, there is possibly a thin sole present which can be cut too short at trimming, causing solar pain and eventually change in the solar portion of the coffin bone. In addition, it is likely that your horse will not land heel first, he will most likely land flat footed, which is fine. If he is landing toe first, then he doesn’t have enough heel present

I would encourage you to have an x-ray taken of the foot to see how thin the sole is and if there is any bone change in the coffin bone. The x-ray will help to determine how to properly align the coffin bone, which will allow sole and hoof growth.

As to the question of the frog, it will always be abnormal as the foot structure is abnormal and a thin, sucked up frog is directly related to the angle of the hoof and coffin bone within the foot. Therefore, the frog changes with the shape of the hoof/angle of the hoof, which is different than an atrophied frog.

This is a difficult case to manage, as you have already experienced. Hopefully we could answer some of your questions and help get you and your horse back on track.