The most common cause of acute lameness in the horse is a hoof abscess. The foot abscess is a localized infection between the sensitive and non-sensitive structures of the hoof wall or sole. Foreign material and bacteria gain entry into the sole/wall junction (white line) or under the sole. This can occur through breaks or fissures, puncture wounds, and hoof wall cracks.
Signs: Sudden onset lameness, increased heat in hoof wall, increased pulse intensity above the hoof, swelling up to the fetlock, and sometimes drainage from the coronary band.
Treatment: The most important treatment is to establish drainage, preferably from the bottom where the entry occurred. Poulticing, Epsom salt soaks and Ichthamol bandaging are all used to help draw out infection. Foot bandaging, and soaking is continued until drainage stops, and lameness is significantly improved. Left untreated the abscess can migrate up the inside of the hoof wall to the coronary band, or into deeper structures of the hoof.
Prevention: Proper trimming and shoeing will decrease forces that weaken the white line area where most infections gain entry. Reduce long toes, sheared heals, and trim at appropriate frequency.
Full thickness hoof wall defects located in the quarter between the toe and the heel. Usually originates at the coronary band and extends at an angle down the weight bearing surface.
Causes: Trauma to the coronary band, damage to underlying tissue from infection, conformation issues, abnormal landing pattern or disproportionate forces on one side of the hoof.
Treatment: Correct underlying cause, if possible, stabilize crack with wires or acrylic composite bonding, shoes to provide support, trim properly to correct landing pattern. Usually, bar shoes are used.
Under Run Heels-Long Toe
Hoof wall horn tubules grow parallel or close to parallel to ground surface, usually due to an excessively long toe, thus creating a broken back hoof/pastern axis.
Causes: Genetics, Environment (continuous or excessive moisture), conformation, Improper trimming and shoeing. Typically, this occurs by allowing an excessively long toe length, combined with a shoe that is too small, and placed too far forward on the weight-bearing surface.
Complications: Increased tension on flexor tendons and ligaments, widening of the white line, abscesses.
Treatment: Shorten toe, set shoe back on foot to encourage heel growth to change direction, load the heel.
Prevention: Trim to maintain proper toe length and hoof angles, maintain parallel pastern axis.
Sheared Heals: Hoof capsule distortion resulting from one heal bulb sitting higher than the other. Due to the weight of the horse not distributed evenly over the whole hoof during landing.
Causes: Inappropriate trimming/shoeing, limb conformation pushes landing forces unequally, attempting to correct gait abnormalities, and chronic lameness.
Hoof distortion, bruising, quarter cracks, deep frog fissures, and thrush.
Treatment: Trim/shoe to create even landing forces. Typically, the hoof is trimmed back to a point that the hoof lands evenly, then a shoe is fitted to the foot (wide web bar shoe), then the affected side is reduced further to remove landing forces. This will allow the affected side to drop back to a more normal position.
Moist dermatitis involving the frog. It is a bacterial infection that destroys the frog tissue and left untreated can invade deeper structures.
Causes: Historically the primary cause was thought to be unhygienic conditions such as dirty/wet environments, infrequent cleaning, and infrequent trimming. Although these factors do play a role, thrush is more likely caused by anything that alters the normal Natural Hoof Cleansing Mechanism.
Treatment & Prevention: Proper balancing and trimming, exercise, remove all devitalized tissue from the frog, and antiseptics.
Acute Laminitis: Initial stages of inflammation and pain associated with insult to the sensitive lamina. It lasts until the horse recovers, OR until evidence of displacement of the coffin bone (Chronic Laminitis).
Chronic Laminitis: Clinical and radiographic signs indicate that the coffin bone has rotated or sunk within the hoof capsule. This occurs due to separation or tearing of the laminar attachments to the inside of the hoof wall.
Causes: Gastrointestinal diseases that cause endotoxin release into the blood stream, trauma, bruising from improper trimming, Cushing’s Disease, & Toxins.
Treatment: In the acute stages this includes treating the primary cause, anti-inflammatories, and foot support through pads or soft bedding substrates. In the chronic stages this includes anti-inflammatories, and corrective trimming and shoeing geared towards realigning the coffin bone to the ground surface and removing weight/pressure forces from the toe to the rear portions of the hoof.
Palmar Foot Pain/ Navicular Disease
Pain associated with the heel of the hoof. The challenge is to determine what is actually painful. Many structures and conditions can be involved. These include the navicular bone, flexor tendons, ligaments, the coffin bone, the coffin joint, under-run heels, sheared heels, and deep-seated thrush.
Clinical Signs: Lameness of one or both front limbs, shifting leg lameness (especially when circled to the right or left), and heal sensitivity with hoof testers.
Diagnosis: Response to digital nerve blocks, radiographic changes, MRI
Treatment: Correct any obvious abnormalities of the hoof, shoe to decrease tension on the flexor tendons, and reduce frog pressure. In addition, anti-inflammatory medications, intra-articular injections, isoxuprine or pentoxyphyline. Neurectomies (cutting the nerve to the heel) can be used successfully in some hard-to-treat cases.
White Line Disease
A poorly understood, yet widespread problem that can affect any horse, any age, any breed, in any conditions. It is characterized by a progressive separation on the inner zone of the hoof wall. The separation is invaded by bacteria, that travel upward perpetuating the breakdown and separation further.
Contributing Factors: Moisture, poor hygiene, and bacterial invasion. Most likely White Line is a result of stresses on the hoof that cause deterioration to the white line zone. Under-run heals, sheared heals, laminitis, club foot, and abscesses.
Treatment: Include radiographs to determine the extent of the separation and other underlying issues, hoof wall resection back to where the separation stops, and antiseptics/ astringents/antibiotics. Any hoof stress factors will need to be corrected, and typically corrective shoeing to transfer weight and pressure away from the toe.