Ask the vet: The foot: Structure, Function, and Disease

AAEP expert, Dr. Karen Blake, answers questions concerning the equine foot, including its structure, function and disease.

Question: I have a 9-year-old miniature horse that has developed chronic laminitis. At this point, he doesn't have significant sinking or rotation, but he is very lame. He is currently on banamine and a supplement from Smartpak called Smartflex Recovery. His feet have been trimmed and there were no problems with his sole or white line. He is receiving probiotics and timothy hay, and a very small amount of Safechoice feed. We don't really have any pasture right now, so that isn't a worry. He walks around, and he seems to lay down when he needs to. He's not stressed, no teeth grinding or grimacing. He actually seems pretty perky for as lame as he is. Is there anything else recommended for the daily management of this condition? I was told that this could take several weeks to months for him to improve. I just want to make him as comfortable as possible. 

What about vaccines for him? I'm hesitant to vaccinate him right now since I do not want to cause a huge immune reaction while he has all of this inflammation going on. There seems to be a huge difference in clinical opinions about risk vs. benefit. We have a lot of mosquitoes that should be emerging any day now. I feel like we should wait until there is some improvement in his lameness to vaccinate, but I don't want to start the process all over again if we can get him to improve.
Poor guy! The most important part of managing laminitis is getting the inflammation down, getting his feet supported (they make miniature-sized Soft Ride boots for minis), keeping him slightly confined (so he doesn't walk all over the place when he is feeling better) and keeping the weight off, which can be especially difficult in these guys. 

Remember that horses (and minis) should be fed 1-2 % of their body weight in hay. For a weight loss program, which almost all minis I see need and especially minis with laminitis, I use a 1% body weight amount. Therefore, a 150 lb mini would get 1.5 lb of hay broken into 2-3 feedings and add in Natures Essentials Enrich 32 to keep their Vit/Min balanced and keep giving them some protein, which is only used for muscle mass. I use this regime until I see significant weight loss. Then they can get bumped up a little to 1.5-2% bwt of hay.

Generally, I also recommend soaking the hay for 30-60 minutes (no longer) to rid the hay of sugars (grass hay especially has significant variation of sugar and can be as high as 30%, which is terrible for horses sensitive to sugar in their diet). 
Additionally, if the new grass is coming up, I restrict their grazing by using a grazing muzzle - I know they don't like it, but it is really important in keeping their weight down!

All these recommendations should help stop the process of laminitis for your miniature horse.

I would try to hold off on the vaccinations as long as you can, however you may also separate out the vaccination so that there's not so much reaction at one time.
Question: My 6-year-old mare is part draft and Paint horse. Her hooves flare out, typically to the back. Are there any good products for this? My farrier has never suggested shoeing as I mostly trail ride.
That is a common occurrence with draft feet - the pancake, as I like to call it. Keeping the feet trimmed with appropriate rounding of the exterior hoof wall will help keep the foot from chipping when it starts to pancake. It is possible that his bone alignment is slightly off, which will make the hoof wall less healthy to stand up to his weight. You could have some radiographs done to determine whether that is happening. 

Shoes will also help to some extent as they 'tether' the hoof wall to an immobile object, but the nails only go to mid-way back on the hoof and will not help if the rear portion of the hoof is the one flaring out. The biotin product I recommend is either the Nanric 100 mg biotin powder or the double strength Farrier's Formula (approx 74 mg biotin). Biotin can help with horn growth of the hoof as well as health of the horn.
Question: We rescued a 11/2 year old Quarter horse filly whose growth plate had been injured on her left front ankle due to the previous owner trying to ride her. She has arthritis starting in it and radiographs show a small piece of bone missing from the ankle. Would a Glucosamine and Chondroitin supplement help with that? We have a farrier also working on her feet.
Yikes! Yes, there is more evidence that oral supplementation is helping horses with joint disease. My personal favorite is the Cosequin ASU plus; it has the typical joint supplements plus avocado and soybean extracts proven to help decrease inflammation/improve joint health as well as HA (Hyaluronic Acid), which is anti-inflammatory as well. Smart Pak makes a similar, as does Grand Meadows. At this point, her fetlock physis (growth plate) has closed and the farrier work, I would recommend, is allowing her easy break over from whatever side is lower towards the ground/fetlock angles away from; this will decrease the stress on the joint.
Question: I know that a normal landing of the hoof should be heel first or flat. However my 14-year-old gelding has one front hoof where the leg itself actually rotates slightly and he lands heel first, but slightly on the outside of the hoof. He has been trimmed and shod normally with both sides of the hoof even and has never had any lameness or other issues. He is used strictly as a trail horse. However, it is something that bothers me and I would like to know if there is a way or a need to trim and shoe him to land normally, or not. Is this an anatomical defect that can not be or should not be messed with since he is sound with the way he lands as is?
It sounds like your horse does have an anatomical reason to land on the outside of the hoof as he walks. This is common in horses that toe in or have slight rotations of their limb higher up. As long as your horse is sound and the farrier is cognizant of keeping the foot trimmed evenly, I would not change your program. Often times, trying to alter the horse's landing pattern actually causes lameness. It should be kept in mind that the horse may develop lameness over the long-term due to the landing pattern as it is bearing more stress on the lateral (outside) aspect of the limb, but that will have to be dealt with when it comes up (and it may never be an issue too!).
Question: I trail ride my horses on mountain trails that have a lot of rock as well as gravel. Is it better to keep horses shod for rocky trail conditions or can the foot harden to non-painfully allow the horse to travel barefoot? Would barefoot abrade the hoof down too much with many miles of trail riding?
It really depends on the horse and how hard the footing is on the mountain. Some rugged horses can handle mountain riding without problems. For the most part, I believe that our domestic horses can't handle the mountain riding without some type of protective foot-ware. Shoeing is usually the easiest and least labor-intensive, but some people have success with Easy Boot Trail shoes, which they apply for the ride. These boots can have rubbing issues on the heels and pastern regions though and should not be worn at all times as the foot needs some fresh air to keep it thrush-free.
Question: We took in an Appendix Quarter horse last summer. He now has, what appears to be, cracks from his frog up the heel to his hairline. He now has thrush. What is the best way to treat this, without further damaging more tissue?
I assume the crack you are talking about is in the middle of the frog and up between the heel bulbs. This is usually caused by sore heels and a decrease in use of the frog. As the heels get sucked upwards, the crevice/crack gets very deep. Your veterinarian can treat these horses by paring away excess frog, even using a scalpel blade to be more precise as the frog gets deeper, then using either a kopertox or sugardyne mixture to dry out that area. Also important is changing the shoeing so that the heel and frog come back down from their sucked up position as the foot gets more comfortable.
Question: How should laminitis be treated for a pregnant mare? She became mildly laminitic with no rotation and foaled just last week. Now without the hormones and the weight of the foal, how do I treat her to return her to soundness? She is currently on a low sugar diet and wearing padded boots that support the frog, and walks with no discomfort. Is there anything else I can do for her?
At this point, especially since she's doing well, it seems like there is nothing more I can suggest besides taking her slow upon your return to riding. However, if you think she is sensitive to insulin (Equine Metabolic Syndrome), then you can always test for those levels in her blood and monitor them so that if her insulin is rising in her blood, you can modify her diet and weight further.
Question: I just realized that my farrier cut the frog down to almost nothing on three of my horses feet. I fired him on the spot but wonder if there is anything I can do in the meantime?
Sometimes in the spring, with the wet weather and mud, it can be easy for a farrier to take a swipe of the frog or even sole too deep as they have been softened by the weather. One product I really enjoy is called Keratex - it's a sole hardener but can be used on the frog as well. It's a liquid, which can be painted on with a small paintbrush, already included with the product. I would apply it once a day for seven days, then go to 2-3 times a week. It's very useful for thin soles or soft soles too.
Question: What is the best, most accepted, correction for a horse with low heel problems? Do wedges only make matters worse?
Wow! That is a very difficult question to answer as many people have differing opinions on the best method to use to correct low heel problems. There are lots of combinations of flat or wedge shoes with wedge pads, which can elevate the low heel. Unfortunately, if the heel is collapsing or underrun, they can make the situation worse as the pad is placing pressure on the collapsed heel and that pressure adds leverage to the damaged heel and increases the crushing force, worsening the problem. However, some farriers are able to use wedge pads/shoes with great success. Alternatively, there is another method to help the low heel called a 'rocker' shoe which elevates the heel portion of the foot by using a round bottom shoe and allowing the horse to 'roll' to the area of most comfort which is usually the toe region and thereby unweights the heel region (which essentially elevates the heel). The goal with these shoes is the create a healthier, more comfortable foot so the heel will eventually grow out to a relatively normal angle (less low).
Question: My Thoroughbred gelding went on a "joy" run last summer, going through deep fields, on two roads, and ran upon railroad tracks for quite a distance, total of 3 miles or so! When I caught up to him, he could barely walk. He kept pulling up one hind leg, then the other. As the day went on, he couldn't hardly stand. His muscles would become rock hard at times. The vet and I both did research to determine what was going on. (His labs were perfect, etc.) With and without the vet, I gave him bute and banamine, altering back and forth. I also started to give acepromozine for the relaxation of the muscles...(I told the vet and she agreed). After 7 weeks, he was better and just a walk under saddle was more than enough for him. I left out LOTS of detail, like uncertain if he should be hand walked vs. stall rest this whole time, etc. My husband wanted to put him down! The horse had good attitude during this entire process so I know he hurt but not to the point of euthanasia! 

He finally abscessed in one hind hoof, then a week later, the other hind. My farrier said that happens even though trauma to the hoof (no nail holes, bruising, etc. present) can be unknown or just a guess. My questions, finally--what do you think caused the abscesses? Hard road? Deep soil in field? He recovered fine, except now he hates the field and WILL NOT agree to be ridden out there! Now he's scared and gets way upset! Any thoughts on this? Thank you!
It sounds like your horse developed rhabdomyolysis (ie: tying up) after his exciting get-away. Commonly, the lab values will not rise until 24 hours after the incident. I agree with your farrier in that the blunt trauma to the soles will cause inflammation within the foot, which can cause serum build-up or even bruising (blood pocket) within the foot - both of which are easily infected fluids. Once the fluid is infected, it becomes known as an abscess where it causes lameness and needs to be released from the foot so the infected fluid can drain out.
Question: I have been trying to research my concerns on-line, but have not come up with information pertaining to my gelding. Captain is a 12-year-old Paso Fino, used for trail riding (and not a lot at that). He's had a very easy life since I've had him (at 4 years of age) and he has not had any particular discipline stresses to his joints since I've had him, using arena work just for general warm-ups in which I use the rail and large 20 meter circles.

This past year he has developed a "popping" movement in both front fetlocks, and I feel it when riding, obviously.  I've been observing other horses in their movements and have not seen this type of action. The popping happens during the full motion of strides.

Last season, we applied an aluminum shoe with a very slight rear wedge, which helped and Captain traveled well over the trails, but there was still a slight visual of this popping. We removed shoes for the year, giving him time off to adjust, observing carefully for any discomfort (with concerns of tendon/ligament stress from angle change). Captain was sound and showed no stress.

I don't ride much in the winter, here, but am starting to begin short warm-ups (straight line riding) and the popping has returned to be very noticeable. There has never been any heat or swelling at the fetlock/pastern areas, nor any sensitivity to palpation. My vet/farrier are scheduled next week for hoof x-rays (I want a baseline) to ensure proper shoeing, to get reading of sole depth, and coffin bone structure.

My question to you:

Have you ever seen anything like this? My farrier and vet, both, concur that this is an odd joint action and suspicion tendon/ligament stress.I appreciate your time in reading this and
look forward to your response.
That is a difficult problem. I think your idea to get radiographs of the feet is an excellent idea. Sometimes, the foot angles will cause the suspensory to create an abnormal angle of the fetlock or pastern, which causes what I would call a pseudoluxation - a luxation of the joint, which is not a true or permanent luxation - and probably is the cause of the 'clicking'. Meaning, when you change the angles of the foot, as you experienced when you placed wedge shoes on your horse, the suspensory ligament drops and allows a more normal fetlock angle and 'corrects' the luxation. It is possible that there is some suspensory pain too which may cause the horse to not want to drop fully into the fetlock, the suspensory should be palpated by your veterinarian for discomfort or swellings. The hoof radiographs should help you to figure out these issues. Good luck!
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?
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: Is a "clubfoot" a heritable trait? 
This is a very good question and so far there is no proof that it is inherited. However, if you take a look at many young foals, you can see the clear difference in hoof angles, which leads me to believe it is heritable. That being said, if you know that the foot may be inherited, surgery can be attempted to correct the condition as it works much better at a younger age.
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?
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.