Mitch Taylor, an American Farrier's Association (AFA) Certified Journeyman Farrier and director of the Kentucky Horseshoeing School in Mt. Eden, Ky., says this condition can be prevented or corrected with good hoof care and nutrition.
For example, says Tia Nelson, DVM, a veterinarian/farrier in Helena, Mont., sometimes horses get shelly feet just because the feet have too much flare due to incorrect--or lack of--trimming.
"Sometimes this is very subtle; people don't recognize the flare until it is pronounced," says Nelson. "Then the feet begin to delaminate. I call them cardboard feet because they look like layers of cardboard and start coming apart."
Taylor feels that correcting many hoof conditions is not just a matter of shoeing them better.
"Sometimes it involves deeper and more metabolic issues such as the immune system and keeping the body (including skin and hooves) healthy," he says.
Overall health and genetics can play a role. A healthy hoof has a nice sheen, like a high-gloss varnish. An unhealthy hoof looks dull, says Taylor.
Nelson says that when someone calls her about a horse they're having problems keeping shoes on, she does a thorough physical exam.
"If I notice the hair coat is rough and mane and tail hairs are broken, I wonder about selenium (either excess or deficiency, since either can lead to the same clinical signs)," Nelson explains. "If selenium is not an issue, we check on other things."
These might include nutrition and trim schedule and quality.
Nutritional issues can be the root of a hoof problem. "Lack of selenium, copper, zinc, or magnesium are common issues, since these are important to good hoof health," says Nelson.
Selenium can be a factor if the horse is deficient in this nutrient, but some horse owners overdo selenium supplements.
"I looked at one horse that had horrible cracks in all four feet, nearly to the hairline all the way around the foot, which is quite unusual," says Nelson. "I asked the owner if she was supplementing selenium, and she showed me all the selenium products she used.
"We live in a selenium-deficient area, so horses with excess selenium are not what I generally see, but this was the first thing I thought when I saw that gelding," says Nelson. "As soon as we got him off the selenium, he started growing out a nice hoof wall and his feet became very healthy."
A horse might not have enough nutrients to grow a good hoof. Nelson recommends using Grand Meadows' Grand Hoof. "I have been very pleased with that hoof product," she says. "But even soybean meal is high in protein and has the double sulfur-bonded amino acids like methionine. A horse needs this to grow good feet. Biotin is also important."
If the horse is an easy keeper, however, be careful not to overdo soybean meal or any other supplement. "You don't need to feed a hoof product to make a good foot. I've had a lot of horses grow fantastically healthy feet on just a quarter-cup of soybean meal each day, along with proper and consistent hoof care," says Nelson.
She usually can tell fairly soon if this type of feeding is making a difference in a horse with hoof problems. "Even though it takes about a year (10 to 12 months) for the hoof to grow from the hairline to the ground at the toe, if I see a change in the growth of hair in the tail and mane, I know we are on the right track," says Nelson. "This can show up in one to two months; the new hair at the base of the mane and tail is more lush and shiny. The same process is taking place in the hooves; it just takes more time."
Healthy feet require amino acids such as methionine, glycine, proline, and glutamine. Vitamin C and copper serve as catalysts in forming a strong hoof horn. Essential fatty acids are needed for proper moisture and pliability. A natural diet of grasses will supply those needs in proper balance. This is why horses on green grass have excellent hoof growth. But a horse fed poor-quality hay might need supplements. Some horses on high-fat diets (such as with added vegetable oil) show improvement in hoof quality. Anything that promotes hair growth promotes hoof growth and health.
Dry conditions can lead to dry, brittle feet, and wet conditions can cause soft, mushy feet. The hoof's natural protective coating can be damaged by constant wet and dry conditions or by standing in manure or urine, and the wall can become chipped and cracked.
A hoof sealer can help feet that have tiny surface cracks caused by moisture changes to keep external moisture and dirty bedding from damaging the foot and internal moisture from escaping.
Some types of bedding (such as pine sawdust or shavings) can also dry the hoof wall. Mud that dries on a hoof can draw out natural oils potentially causing harm.
Taylor says hot seating shoes can help. This is more popular in wet climates to help dry out and seal the foot, but it's also beneficial in dry regions. "When we sear the feet with a hot shoe, it actually seals the moisture in and doesn't let it leak out from the freshly trimmed foot," he explains.
One of the best ways to create healthier feet is to put horses on grass pasture rather than in stalls or hard, dry paddocks. Grass provides the ideal environment for feet, and grazing provides the appropriate nutrients for a healthy hoof. Regular exercise and pasture turnout will often strengthen unhealthy feet.
Foot structure, hoof integrity, hoof wall thickness, hardness, and durability are individual traits in every horse that are influenced by heredity as well as environment.
Taylor says, "Here in Kentucky, I see a lot of line-bred horses (the horses' relatives were bred to one another to "set" certain characteristics in the progeny) that don't have as strong an immune system or as much hardness/toughness of the feet. I see a lot of shelly feet with many superficial cracks in the hoof wall."
We can feed a horse the resources his body needs to build good keratinized tissue, but some horses don't have the ability to utilize the B vitamins or whatever else we are feeding, so their feet won't benefit as much, says Taylor. Two horses doing the same work, living in the same conditions, and eating the same feed might have very different feet, and this difference might be genetic.
A horse with good feet will usually grow a half-inch to three-quarters of an inch of new horn in 10 weeks, while another horse might go 10 weeks between shoeing sessions and the feet won't grow much at all.
"Thoroughbreds tend to have thin hoof walls," says Nelson. "Thin walls tend to be less tolerant of abuse or neglect." Putting off a trim might not be obvious neglect, but it can play a role in the horse's overall welfare.
Some horses have more fragile feet than others, but if you can care for them properly and consistently, they can do fine. "I am a big fan of barefoot," says Nelson, "but there are some horses that can't go barefoot if they are being used. They do fine in a grassy pasture, but as soon as you take them out on the road and ask them to trot on the gravel, their feet break."
Genetics makes a big difference, but remember that just because two horses are closely related doesn't mean they inherit the same foot structure or hardness.
Trimming and Shoeing
Regular trimming and shoeing is important, but proper care is as important as frequent care, says Nelson. Hoof care is a very individual thing. "The horse may get his feet trimmed/shod every eight weeks, but the shoer isn't taking off enough flare, perhaps," she says. "Or the foot may not be backed up enough and the toes are too forward and there is a lot of stress on the horn tubules."
Taylor says if too much time elapses between farrier visits, the stress on the hoof creates wall separation. "Not only is the wall flaring, bending, and cracking (letting in pathogens), but there is separation on the bottom (at the ground surface), as well," says Taylor. "If you put nails in the compromised hoof wall, you drag more pathogens in. If we can turn these horses out barefoot after trimming and giving the foot a good pasture roll (and keeping it regularly trimmed that way), we have a much healthier foot in three to four months."
In many cases, shelly feet are man-made. Regular, competent foot care, at the right time for that particular horse, is the best way to deal with feet. "Not every horse needs done every six weeks," says Taylor. "Some need done every three to four weeks, while others can go eight weeks. It's up to the farrier to read the situation. Anytime there's excessive growth that goes past the sole and puts extra pressure on the wall, the wall tends to pull away from the sole and open up the white line to opportunistic pathogens."
When Nelson is called to shoe a horse with crumbly feet, she can usually get nails in at the heels and at the toe, "especially if I stick the shoe on the forge and manufacture my own nail holes beyond the reach of the ones that are there," she says. "I tell the owner that the first shoes I put on this horse should be considered just a bandage. They're not shoes to go barrel racing or endurance racing on. These are just to protect the hoof while it grows."
Some farriers like to make their own shoes or use several brands of factory shoes, just so they are able to accommodate every horse. The nail holes in some shoes might be too far from the outer edge of the shoe, or too close to the edge. The holes must be over the white line. If nails enter the hoof wall instead of the white line, they can split the wall. Using shoes with clips allows the farrier to secure the shoe with a finer nail. Side clips or quarter clips halt any lateral movement so the shoe doesn't wear on the nail holes.
While a horse is growing a better foot, you can use shoes for protection to keep the hoof wall from breaking and cracking, says Nelson. "Just balancing the diet and making sure the flare is removed will eventually grow a better foot," she says. "You can use glue-on shoes in the meantime if there is nothing to nail to, or protective hoof boots (Easyboots, Old Macs, etc.). Even though I'm a big advocate of having a horse barefoot, there are some horses that can't be barefoot and do their job. Even if your 1,200- to 1,400-pound Thoroughbred has feet of good size (such as Number 2 American size shoes), if his hoof walls are only one-eighth-inch to one-quarter-inch thick, his feet don't have the strength and substance to hold up. If he has thin hoof walls, you can assume he has thin soles as well, and they don't offer much protection to the coffin bone and other sensitive structures within the foot."
Taylor says proper trimming involves "tightening up" the foot and getting it back to normal shape--for that particular horse. "Normal means the shape of the coffin bone," Taylor notes. "A good farrier can visualize this through the foot, using external reference points, and trim the foot to the right depth and length without overtrimming."
Shelly feet can be caused by such things as improper or unbalanced diets, genetics, or conformation. Once the determination is made that the horse's feet are cared for and nourished properly, a farrier should work to make the hoof a normal shape for that horse to reduce stresses on the hoof wall and internal structures.
HOLISTIC HOOF CARE
Mitch Taylor, an American Farrier's Association (AFA) Certified Journeyman Farrier and director of the Kentucky Horseshoeing School in Mt. Eden, Ky., is a big believer in whole body hoof care when solving the problem of weak and shelly feet. "I think a lot of it has to do with horses being stressed, affecting their cortisol levels, which affects other parts of the endocrine system so their resistance goes down," he theorizes. "They are more vulnerable to opportunistic pathogens, including some that affect the feet.
"There are obviously some genetic factors we can't control, but there are some environmental issues we can influence--including quality of forage and other feeds, amount of time the horses are at pasture, how often they are dewormed, etc.," he notes. "Horse owners can work with their county extension agent and have their feeds tested.
"Another thing I ask some clients to do is have a complete blood evaluation (complete blood count and a hormone panel) on a horse with poor feet, to see if there is anything metabolically wrong," he says. "I like the vet to look at the endocrine system. PPID (pituitary pars intermedia dysfunction, also known as Cushing's disease), insulin resistance, or low thyroid hormone (T-4) can be factors, for example. Some horses do tremendously well with appropriate thyroxine therapy either orally or by injection. The injectable compounded form can be given once a month. Imbalanced hormone profiles may affect the peripheral circulation; the vascular bed of the foot may be affected by some of these hormones, which affect quality and quantity of hoof growth. A $50 blood test may actually save money in the long run." --Heather Smith Thomas
If a foot is too shelly to hold nails, use glue-on shoes, says Mitch Taylor, an American Farrier's Association (AFA) Certified Journeyman Farrier and director of the Kentucky Horseshoeing School in Mt. Eden, Ky. "I like the sole glue shoes," he says. "I may make a shoe, fit it and clip it, putting the side clips way back in the quarters to help stablize them, and maybe hot seat the shoe on. Then I'll take it off and dress the foot and sand it down a bit, and glue the shoe on rather than nailing it. This tends to stop or minimize any expansion when the foot is loaded (the temporary distortion caused by shock dissipation and blood perfusion into the tissues)."
This is like putting a broken bone in a cast to eliminate movemen t temporarily so it can heal, even though it's not the best thing for your arm because it may get weak from immobility. But the bone can start healing and you can strengthen the arm later.
"I may immobilize the quarters on a bad foot after first making sure the toe is not too long and the foot is balanced, then use a glue-on shoe," explains Taylor. "On some you just put glue on the foot surface of the shoe and glue the shoe to the hoof wall and white line."
There are also shoes that have bonded fiberglass and Kevlar fabric that extend up to where the nails are, maybe an inch up the hoof wall, and it glues all the way around, he says. He usually doesn't use these because he says they cover a big part of the cracked wall and create an airless environment that might seal in pathogens.
"When I use a glue-on shoe, I may squirt some Equi-Thane in the bottom of the foot to pad the sole and let it share some of the load for awhile to give the foot a break, then work on the hoof capsule from shoeing to shoeing," Taylor says. "Whenever there's active bacteria in the foot, however, we need to debride and clean that out. It's important we don't glue over active bacteria. When the glue sets up (catalyzes and starts to cure), it heats to more than 100°F, and these bacteria love heat."
If a horse can't go barefoot and needs a glue-on shoe, Taylor takes two or three days to prepare it for the shoe--to debride the white line and any deep cracks. "I open that crack up and soak it in acetone or formaldehyde or some other non-oil base solution to kill any residual bacteria in there," he says. "Once the foot is really clean and dried out, then I can start doing whatever I need to do for the shoe." --Heather Smith Thomas
About the Author
Heather Smith Thomas ranches with her husband near Salmon, Idaho, raising cattle and a few horses. She has a B.A. in English and history from University of Puget Sound (1966). She has raised and trained horses for 50 years, and has been writing freelance articles and books nearly that long, publishing 20 books and more than 9,000 articles for horse and livestock publications. Some of her books include Understanding Equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, Storey's Guide to Raising Horses and Storey's Guide to Training Horses. Besides having her own blog, www.heathersmiththomas.blogspot.com, she writes a biweekly blog at http://insidestorey.blogspot.com that comes out on Tuesdays.
POLL: Colic Surgery