It seems like only yesterday your horse soared over that 4-foot oxer, slid to that perfect stop in a reining pattern, or ambled smoothly down that shady trail. Now, watching him limp three-legged down the barn aisle, you wonder, "How could this have happened so fast? How could I have not seen this coming?"
Most hoof problems don't magically occur overnight. They usually result from a combination of factors weighing on the foot. Recently, Ric Redden, DVM, founder of the International Equine Podiatry Center near Versailles, Ky., spoke with The Horse about several common and sometimes debilitating hoof problems that can materialize with little or no warning, such as laminitis, white line disease, and hoof abscesses.
Barbaro brought laminitis back into the public eye when he developed the disorder after five weeks of treatment for his shattered right hind leg. On July 13, he was diagnosed with unilateral laminitis in his left hind hoof, resulting from overloading his good limb to alleviate the pressure on his fractured one. While non-horse people might not fully understand the serious nature of this disorder, it's important that horse owners do.
There are two basic classifications of laminitis: acute and chronic. Acute laminitis describes the initial stages of inflammation and early clinical signs of the disease such as warm feet, bounding digital pulses, and abnormal positioning of the coffin bone inside the hoof. This phase lasts about 72 hours. Chronic laminitis often follows. Chronic laminitis begins with separation of the dermal and epidermal lamellae that normally anchor the coffin bone securely to the hoof wall, kind of like Velcro. This separation results in the inner structures collapsing away from the hoof wall.
At this point, when there is rotation or sinking of the coffin bone within the foot, this might be referred to as founder. Not all laminitic horses founder, but all foundered horses have laminitis.
"Laminitis is one of the most complex disease syndromes facing the veterinarian and farrier," Redden says. "The disease is extremely complex and not well understood. And to compound the problem, the foot is actually a very poorly understood piece of the equine anatomy. But advanced technology, current research, and numerous articles concerning the foot have also fostered new concepts and ultimately a whole new mindset."
Many factors can trigger the onset of laminitis. "In my experience, laminitis is always secondary to another disease process," he explains. "It can be triggered by colic, Potomac horse fever, salmonella, stress, retained placenta, or traumatic injury. Laminitis also can be triggered by obesity and overeating."
Early Stages Laminitis can affect one or more feet, but it most commonly affects both front feet. Lameness is the most common sign indicating its onset. Most horses with laminitic forefeet will also exhibit a characteristic stance by bringing their hind feet under their bellies to help unload the front feet. They push their front feet out in front of them to relieve the toes, which are the sore areas of a laminitic foot. This stance is often called "pointing." In severe cases, the horse might lie down and be reluctant to get up.
"If this occurs, the prognosis can be extremely grave unless you move very rapidly using reversal therapy (mechanically undoing the casual factors)," Redden explains. "The most obvious sign is acute lameness or signs of pain. If you have these, you most likely have an emergency. Even if the horse ultimately does not have laminitis, its pain requires prompt attention, so call your veterinarian and your farrier." Involving the farrier is necessary because he or she knows the horse's feet and can understand what changes have occurred.
"On closer examination, you may find that the horse has a bounding (digital) pulse," Redden explains. "Always check the pulse before moving the animal, because even in a healthy horse, a few steps can increase the pressure within the blood vessels."
Most laminitic horses' feet will be warmer than normal because of the inflammation, but in rare cases they can be ice cold.
Treatment "I don't think there's one general way to treat laminitis, and there probably never will be," Redden says. "Laminitis treatment has to be designed for the individual--every foot and every horse is unique."
Redden says his first step to treating laminitis is to take baseline X rays that clearly describe the soft-tissue parameters of the foot, and perform a venogram when the client's financial circumstances allow. This provides a baseline for the veterinarian and farrier to measure the horse's progress.
"You can have significant changes in the first six to eight hours, so it's vital to get that baseline," he explains. "In the case of a high degree of insult, the horse can walk out of his foot (slough his hoof wall) in the first 24 hours. Fortunately, the majority of cases don't fall into this category, but if they do, they demand immediate, effective reversal therapy."
The degree of changes from that baseline and how quickly they occur tell the veterinarian and farrier how severe the case is, which helps dictate the treatment.
Treatment for the onset of laminitis begins with addressing the inflammatory stage as well as eliminating the disease's causal factors, such as rich grass for a Cushingoid horse. Redden says it's important that your veterinarian and farrier work together to reverse the mechanical forces that strain sensitive areas of the foot, such as the laminae and the sole corium.
After a horse has a bout of laminitis, Redden says it is not likely to do so again unless the horse is subjected to conditions like those that led to the original episode.
Horses with recurrent laminitis (more than one unrelated episode) have a relatively poor prognosis, especially if there is leftover scarring of the laminae that compromises their attachment of the bone to the hoof wall. This scarring can be seen on radiographs, and sometimes externally as rough, rippled hoof wall at the toe.
Depending on the severity of the laminitic episode, full recovery might take anywhere from 45 days to 1ï¿½ years, or the horse might never regain soundness.
Redden says, "It's all about having an understanding of the mechanics--providing blood flow to the places that need it. The quicker you get help for your horse, the greater the chances for recovery."
For more on laminitis, see the Laminitis category under Lameness (Hoof) and Shoeing at www.TheHorse.com.
White Line Disease
"White line disease (WLD) is a term used to describe a keratolytic process (one that destroys the structural protein keratin) on the solar surface of the hoof, which is characterized by a separation of the inner zone of the hoof wall (which is white in color)," explains Redden. Simply put, WLD is the separation of the inner hoof wall from its outer layers caused by opportunistic pathogens. This separation occurs within the stratum medium.
According to Redden, this process is usually secondary to a mechanical hoof problem that causes an initial hoof wall separation.
These problems might include flexural deformities (such as contracted tendons), club foot, chronic laminitis, hoof cracks, chronic infection (abscesses or gravel), injuries that cause scarring of the stratum medium, chemical imbalances, or direct trauma with subsequent bleeding.
Early Stages In its early stages, WLD is not easily detected. It is characterized by a small, powdery area located in the white zone of the hoof wall.
"As the horn wall deteriorates, the sole pushes forward and covers the deterioration as fast as it occurs," Redden says. "When a farrier pulls the shoe off, he can't see that white chalky area. Radiographically is the only way to detect these early."
The disease can be isolated in one foot, or it can affect multiple feet. It is most often found in a club foot or a foot with high heels.
The disease actually begins when the fungus and bacteria invade a weakened area of the horn wall or a preexisting scar. WLD most commonly affects the toe and the interior quarters of the foot. Pathogens invade these openings and progressively destroy the inner hoof wall. Factors contributing to this situation are not well defined.
Treatment Treatment for WLD varies according to hoof involvement and the severity of the disease.
"Simply applying a rocker shoe to reduce the DDFT (deep digital flexor tendon) tension can work very well in the majority of cases without having to remove a large area of the hoof wall," Redden explains.
However, when damage to the hoof is to severe, removing the infected areas of the hoof wall (resection) is necessary to allow access to treat the pathogens. Once the veterinarian or farrier removes the infected areas, he or she soaks the foot in a chlorine-based solvent to help kill any pathogens that are still present.
Depending on the degree of infection, the hoof wall can take several weeks to several months to heal. Some horses with less progressive cases of WLD are able to return to work almost immediately.
"Even horses kept in the most immaculate environment can be affected with white line disease," Redden says. "It's not directly related to hygiene or negligent farrier care."
For more on WLD, see the White Line Disease category under Lameness (Hoof) and Shoeing at www.TheHorse.com.
Hoof abscesses can cause sudden and sometimes severe lameness in horses. These are localized accumulations of pus between the germinal (growth layer) and keratinized layers of the hoof wall. They are found most commonly in the sole, but can be located elsewhere within the hoof. The infection and pressure of pus accumulation can cause severe pain.
Hoof abscesses can be caused by sole penetration by a sharp object (that introduces pathogens deep within the hoof), bacterial invasion of a hoof crack, or infection of a bruised sole. "Gravel" is sometimes used as a lay term to describe abscesses that are forced up along the hoof wall to break and drain at the coronary band.
Early Stages Typical signs of hoof abscesses include acute to severe lameness where the horse bears minimal to no weight on the affected limb, an increased digital pulse, and heat in the limb.
Hoof abscesses are typically superficial and always affect the sensitive tissue of the hoof. Redden warns that leaving abscesses untreated can undermine the foot's integrity, leading to a prolonged and often costly layup period.
Treatment "Treatment for superficial abscesses usually means thoroughly cleaning the hoof and locating the point of entry or the rode map that says this is where the abscess it," Redden says. "Then, opening a very, very small hole to allow drainage (about the size of a pencil tip). The horse will usually exhibit instant relief when the pressure built up by the trapped infection is released. A very large hole will cause prolapse of the sensitive tissue and create a larger problem than you had initially."
It's important to protect the area while the hole is allowed to heal. Redden says, "When you have a hole in the bottom of a foot, you have to protect that hole." Bandage the foot with a betadine (never use a strong iodine solution) wrap, and use a hospital shoe or pad to help protect it.
For more information on abscesses, see the Abscesses category under Lameness (Hoof) and Shoeing at www.TheHorse.com.
Redden reminds horse owners, "Every acute foot problem has the potential to be an emergency. Therefore, never ignore the lameness and hope that it will go away. Call your veterinarian and farrier for a consultation right away. Together, they can quickly determine the significance of the problem and establish a course of treatment."
"Venograms offer extremely useful information about the degree of damage that has occurred to the vascular supply of the foot," Redden explains. "It is a technique-sensitive procedure that requires skilled involvement and good interpretation experience before it should be used as a aid for treating the laminitic syndrome.
"The venogram will reveal significant vascular damage long before radiographic or clinical evidence. They are the basis of all my mechanical and surgical protocols. They have greatly improved the prognosis for even the most severe cases. Time is of the essence with all laminitic cases."--Chad Mendell
MORE PROBLEMS--HOOF CRACKS AND THRUSH
Hoof cracks These can be superficial defects or severe problems that cause lameness. They can stem from a variety of causes, including laminitis, trauma, repetitive concussion on a hard surface, or imbalanced feet.
Vertical hoof cracks are common in horses with poor hoof care or those with excessively dry, shelly hooves. An injury to the coronary band can also result in a vertical hoof crack. Internal imbalance can cause surface hoof cracks in even the best of shoeing.
Hoof cracks provide an opportunity for pathogens to invade the hoof wall, which can lead to lameness-causing infections and white line disease. Some hoof cracks require external fixation. Screws and surgical steel wire are used to lace the crack together to prevent additional damage.
Thrush This is a bacterial infection of the horse's frog and sole. It is prevalent in horses that are kept in unclean conditions such as muck-filled stalls or paddocks, but can occur in any horse. Thrush-infected feet produce an offensive odor and a black discharge around the frog. If thrush is allowed to progress far enough that the sensitive areas of the hoof are affected, lameness will result.
Several treatments with an iodine or phenol product usually kill the pathogens involved. To prevent thrush from occurring and help a horse recover from it, owners should perform proper hoof hygiene (regularly pick debris from the horse's hooves), maintain clean, dry stall/pasture footing, and schedule routine farrier visits.--Chad Mendell
About the Author
Chad Mendell is the former Managing Editor for TheHorse.com .
POLL: University Equine Hospitals