As far back as I can remember, soaking the equine foot has played a major role in the treatment of common foot ailments such as abscesses, puncture wounds, corns, foot bruising and laminitis. Over the years, I have questioned the therapeutic value of this practice. Does soaking the foot actually draw infection out, increase circulation or does it just plain soften the foot? In my opinion, the principle indication for soaking feet is to soften hard hooves so that it is easier to pare the sole to expose and drain an abscess. In this circumstance, foot soaking is performed over a very limited time period (12 to 24 hours). What happens to the foot during chronic foot soaking to draw out an abscess or treat sole bruising, etc.? By chronic foot soaking, we mean soaking on a regular basis for days or even weeks.

There is no question that excessive moisture will damage the hoof wall. The more the foot is soaked, the more the hoof softens. The hoof wall quickly deteriorates, the wall begins to flake and separate and the loss of integrity allows it to expand or bend outward. At the same time, the white line width increases and the sole begins to drop and become closer to the ground. As the softening process continues, the horse begins to walk on the sole, creating another source of discomfort. Many times, this will mimic an abscess that has not completely resolved. It is believed that soaking damages the protective barrier on the foot (periople) and the widened sole wall junction thereby allowing additional microorganisms to penetrate and further damage the wall. Over-softening of the foot can potentially weaken it. The softened hoof wall does not hold nails well so it is difficult to replace or maintain a shoe on a chronically soaked foot.

Chronic foot soaking for an abscess can actually prolong the healing process. In many cases, the pocket resulting from the accumulation of exudate from the abscess will be prevented from draining and drying up as the softened structures of the chronically soaked foot compress the affected area.

Poultices:

An alternative method of localizing abscesses or drawing out inflammation is through the use of a poultice. The poultice provides a warm moist hydroscopic environment which stays in contact with the foot twenty-four hours a day but does not have the detrimental effects of continuous soaking. There are many good commercial poultices on the market. A medicated poultice [Animalintex®] is an excellent first choice when a poultice is indicated. The Animalintex® poultice, made of multiple layers of medication-impregnated cotton sheets, is immersed in hot water, the excess water is squeezed out and the poultice is applied to the foot, covering the ground surface and extending over the coronary band. The poultice has its own plastic outer covering to maintain heat. It is left in place for at least 48 hours. Moist heat applied to the coronary band may also help an abscess to break out spontaneously.

Another useful form of poultice is a combination of wheat bran and Epsom Salts (2 parts bran and 1 part salts). This poultice is cumbersome but has certainly withstood the test of time. Packing the foot with Ichthammol or a combination of Ichthammol and glycerin is also used frequently with good results reported.

Whichever poultice is used, it must be held in place with a bandage. An ideal foot bandage is a medium-sized disposable diaper covering the enclosed medication. For more padding, use multiple diapers. For a sweating effect, use plastic-covered diapers and duct tape. For more breathing, use non-plastic covered diapers and gauze bandage. The bandaged foot is protected as well as medicated. A rubber Easy Boot® can also be used for protection, but is difficult to place over a hoof that is bandaged with poultice.

Two clinical situations in which foot soaking has traditionally been a major part of treatment are hoof abscess and foot bruising. When a hoof abscess is opened, foot soaking has been the time-honored method to "draw" out the infection. Similarly, with chronic subsolar foot bruising, foot soaking has been prescribed to draw out the inflammation and discomfort.

Abscess:

When presented with a horse that is acutely lame and shows pain everywhere on hoof testers, soaking in hot water during the first 12 to 24 hours may be useful to localize the abscess. When the hoof is extremely dry and hard, soaking will also soften the foot to the point where it can be explored with a hoof knife and drainage established. In the case of an extremely dry, hard foot where a puncture wound to the frog area is suspected, soaking will allow the frog to be pared so that the point of entry can be identified.

Subsolar abscesses gain entry to the underlying corium through a defect or separation in the white line or a penetrating wound through the sole. The horse may be acutely lame or the lameness may develop over a few days as in the case of an improperly placed or "close" nail. The area of pain is localized with hoof testers and then explored superficially with a hoof knife until the point of entry is located. In the case of suspected nail abscess, the foot is poulticed until soft enough to explore or until the nail abscess has "ripened" and can be drained. When the tract is located in the white line, the abscess is drained by notching out the adjacent wall using a bone curette rather than removing any sole. By using a small bone curette, the tract can be followed at an angle under the sole. The sole is left intact for protection and no sensitive tissue is exposed. A large opening is not necessary for drainage. If pressure is applied to the adjacent sole and additional exudate is expressed or if a bubble is observed, there is adequate drainage. When weight is borne on the affected foot, exudate will be continually forced out and drainage will be maintained. Soaking the foot in a hypertonic solution once at the time an abscess is drained may also have some merit. However, in order for any solution to draw infection or clean up the affected area, the solution must be hypertonic which can be achieved by saturating it with a salt. To make a saturated solution, MgSO4 (Epsom salts) is added to hot water until no more salt can be dissolved.

Alternatively, my preference is to flush the wound under pressure with a dilute solution of povidone iodine (Betadine®). Betadine® is an antiseptic but also has antimicrobial and astringent (drying) properties. Gauze sponges saturated with Betadine® are applied to the bottom of the foot and a bandage is applied. A poultice can also be used for the first few days following drainage of an abscess. Tetanus prophylaxis should always be administered. The antiseptic pack or poultice is changed on a daily or every-other-day basis until the tract is dry and soundness has returned. The shoe is then replaced. Alternatively, once marked improvement has been observed, a wide web shoe with a 5/16 inch hole drilled directly over the draining tract in the while line may be applied. The hole is tapped using a 3/8 inch BSW tap. Cotton saturated with an antiseptic is packed in the drilled hole and a stud guard is screwed in the hole to keep the medication in place. The medication is changed on a daily basis. Work can resume as soon as full soundness is attained.

Puncture Wounds:

If a puncture wound in the sole has occurred, veterinary care is indicated. In the case of a puncture wound to the sole, whether acute or chronic, drainage must be established. When the puncture is accompanied by severe lameness, radiographs should be taken to rule out a fracture of the third phalanx (P3). Again using a bone curette, a small circular opening is created at the site of the puncture wound to allow drainage. Any diseased or necrotic tissue is removed. The smallest possible opening is always made. If a large wound is created, excess granulation tissue will prolong the healing and cornification of the tissue in the defect. The wound is flushed as before and placed in an antiseptic pack until drainage ceases and the wound is dry. The horse is then shod. Depending on the size of the wound or the need for continued treatment, either a shoe and pad or a shoe with a treatment plate is used. Antibiotics are seldom used.

Foot Bruising:

Subsolar bruising may be a cause and effect situation in that there is usually a predisposing factor causing the bruising. Bruising results from repetitive trauma to the sole when there is insufficient sole depth. The sole is not designed to support weight and flat footed horses are prone to chronic foot bruising. Flat soles may be normal for a particular horse or may be caused by a disease process, such as flexure deformities and previous or chronic laminitis, or by farrier care as in the case of the long toe-low heel conformation, by excess removal of hoof wall leading to sole pressure, or by excessive removal of horny sole.

Foot soaking has traditionally played a major role in the treatment of bruised soles in an attempt to draw out or relieve inflammation. In reality, chronic soaking may worsen the problem by softening the foot to the point where the sole provides even less protection to the sensitive corium above. In fact, foot bruising is a common problem in show horses during the warmer months when they are frequently bathed and the feet are therefore continually in water. The excessive moisture weakens the hoof wall. As it weakens, cracks and begins to spread, the sole gets closer to the ground and becomes more prone to bruising.

It is this author's opinion that treatment of foot bruises should be directed toward toughening the hoof capsule, relieving inflammation systemically (using Butazolidin and possibly a vasodilator) and correcting the cause of the bruising. Instead of soaking, the horse is placed in a stall with shavings or sawdust which allows the feet to dry out. Preparations which toughen the hoof capsule and sole can be applied daily if desired. Foot care is directed at correcting abnormal conformation of the foot as much as possible. This may consist of not removing any sole from the ground surface, backing up the toe from the dorsal wall and moving the plane of support in a palmer direction. The shoe of choice advocated over the years by Dr. Bill Moyer is a square-toe egg bar with the sole surface of the shoe well concaved using a hand grinder.

Conclusion:

There has been very little if any veterinary research on the therapeutic value of soaking horses' feet. It may be one of those age-old traditions that have been passed down from horseman to horseman or maybe somebody once said it was a good thing to do and no one has wanted to contradict that. If we look at the anatomy of the foot, its physiology and the thickness of the hoof capsule, it becomes questionable if soaking in water provides any beneficial effects. As foot soaking remains a controversial issue between the veterinary and farrier professions, continued communication between both parties is essential to assess its continuing benefits.

Stephen E. O'Grady, DVM, MRCVS

Dr. Stephen E. O'Grady is an equine practitioner and farrier practicing in the Northern Virginia area. He is also a member of the Farrier's Liaison Committee of the American Association of Equine Practitioners.
 

References:

1 Turner, TA, personal communication, St. Paul MN.

2. Animalintex—Robinson Animal Healthcare, Chesterfield, England. Distributed in the U.S. by Kustom Enterprises in Kentucky.

3. Mansmann RA, personal communication, Raleigh NC.

4. Moyer W, personal communication, College Station TX.

5. Keratex Hoof Hardener, Advanced Equine Products, Versailles KY.