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Lameness is a major health issue in the dairy industry primarily, although beef cattle are affected as well. Lame cows lose weight and body condiition, as well as milk production. In most dairy herds, the primary cause of lameness is claw disorders associiated with laminitis (founder). Early detection and prompt treatment minimize losses, improve chances of recovery and reduce animal pain and suffering. Lesions causing lameness are found in the feet in the majority of cases, with the vast majority in the rear feet. Lesions in the rear feet are found more often on the outside claw, with white line disease and sole ulcers accounting for the majority of the lesions. Hoof Anatomy The hoof grows from the coronary band at a rate of 1/4 inch per month. The rate of growth depends on the cow's genetics, environment and nutrition. The rate of hoof growth is faster in the rear feet as compared to the front feet. The hoof is composed of the outer wall, white line, sole and heels. The hoof wall, sole and heal are made of keratin (like hair) and water. They are not very thick and cover tissues containing nerves and blood vessels. The outer claw of the hind foot grows faster than the inner claw; the opposite is found on the front. The heel bulb area responds to stress and weight by compression. The major weight bearing area of the foot is the outside part of the outside claw. A hoof responds to greater weight by depositing greater amounts of keratin. The inner walls of the front feet bear more weight as the cow matures. Within the hoof wall, laminae reduce impacts. These thin structures are part of the corium, or quick, rich in blood vessels and nerves. The corium is positioned between the foot bone and the hoof wall and is vulnerable to inflammation, leading to swelling resulting in pressure, pain and tissue damage (laminitis or founder). On the underside of the foot, the sole is formed by the corium and the junction of the hoof wall and the sole is called the white line. This line is located around the circumference of the foot. The softer tissue in this area is prone to penetration by stones or grit. The corium produces the hoof horn and sole; the healther the corium the better the horn produced. Diseases such as laminitis result in weaker hoof horn that does not support the body weight as well. Beneath the corum lies the coffin or pedal bone, which is surrounded by and suspended within the corium. Laminitis Laminitis, or founder, is characterized by edema (swelling), hemorrhage (bleeding) and cell death in corium tissues. This destruction can result in separation of corium layers. This may allow the pedal bone to compress the corium, causing sole ulcers. These most typically form at the heel and are characterized by a localized loss of horny sole, resulting in exposure of the sensitive corium. This type of lameness is debilitating and painful and may result in infections of the deep tissues of the digit. Treatment needs to be aggressive and consists of removal of dead or dying tissue and elevation of the affected claw by use of a foot block attached to the unaffected claw. Any healthy tissue should be left alone. Another result of laminitis is disruption of blood flow to the corium, resulting in formation of an abscess should the tissue die. These abscesses often occur at the white line and cause acute lameness Any penetration of foreign material in the white line can also result in abscess formation. Laminitis results in distorted hoof growth, separation of hoof layers and widening of the white line. In addition, hoof horn is softer, thinner and more subject to damage. Accelerated hoof growth caused by laminitis also results in the cow's weight being distributed to the back of her heels with uneven weight distribution over alll four claws in the rear. Signs of subclinical laminitis include: - pink staining of the hoof horn or hemorrhages in the sole
- soft, yellow, waxy hoof horn that is easily cut with a hoof knife
- increased incidence of toe ulcers and sole abscesses
Some inciting causes of laminitis include: - confinement on hard surfaces
- heat stress
- rumen acidosis
- improperly formulated total mixed ration (TMR)
Sole Ulcers Sole ulcers are a painful lesion often occurring on the inner side of the outside claw. It is noted as a bulge of pinkish tissue sticking through the sole. This lesion is usually associated with laminitis. If 10% of the herd has sole ulcers, it indicates a herd problem of laminitis. Other factors that can predispose to sole ulcers are moisture, manure, excessive wear on hard surfaces and poor hoof care. Sole ulcers often occur in both hind limbs. Digital Dermatitis Digital dermatitis is also known as heel warts, hairy foot warts, strawberry foot disease, raspberry heel, digital papillomatosis and Mortellaro disease. Pronounced lameness and excessive recumbency are observed. These lesions are raised, red and yellow patches and usually located at the back of the foot above the heel. These lesions are painful and prone to bleeding when palpated. Lesions may persist for many months and often regress with dry weather. Digital dermatitis is most likely caused by a spirochete and is contagious. A dirty environment with wet stalls, poorly drained lots and standing water may predispose cattle to dermatitis. It is likely that unaffected cattle harbor the organism on their feet; stress or environmental factors may result in manifestations of disease. Foot Rot Foot rot is an infection of the foot occurring most commonly high between the claws. The common cause of this infection is a bacterium, Fusiformis necrophorus, which can build-up in the environment. Lameness usually occurs on one foot only, with swelling above the coronet and spreading of the claws. Cracks can develop in the interdigital space (between the claws). A foul-smelling exudate is usually noticeable. If left untreated, deeper tissues may become infected with involvement of the joint space or tendon sheath resulting in permanent lameness. Heel Erosions/Underrun Heels Heel erosions being at the heel bulb. Pits develop in this area, becoming filled with bacteria and black material. Separation of the horn results in a flap of tissue. A new sole can develop underneath and the material becomes trapped between the layers. A wet, dirty confined environment and overgrown hooves are commonly associated with heel erosions. Treatment - restore feet to proper hardness: standing in dry soil or sand, using a dry mineral mix in a walk-through foot box
- foot rot: parenteral use of antibiotics and/or local treatment. Washing the interdigital area and removing necrotic tissue. Topical dressings or antibiotics or antiseptics. Isolate affected cows, sanitize high density areas and use a foot bath containing 5% copper sulfate at a depth of 4 inches minimum.
- heel erosions: remove all unsound horn, treat exposed area with disinfectant, confine cow until the exposed sole hardens. A protective bandage may be placed over severe cases. Trim feet regularly and avoid excessive exposure to wet environments.
- sole ulcers: relieve pressure on the ulcer by paring out the affected area, applying a bandage and blocking or elevating the healthy toe in order to reduce pressure on the affected toe.
- digital dermatitis: topical application of oxytetracylcine or injectable use of oxytetracycline, topical sprays of iodine or iodized copper, use of a concentrated foot bath containing a 9-10% copper sulfate solution.
Prevention Nutrition - include forages at no less than 1.4 % of body weight
- forage should make up no less than 40-45% of the total dry matter intake
- evaluate forage and total neutral detergent fiber (NDF). The minimum NDF intake as a percentage of body weight should be 0.85. The minimum total NDF as a percent of body weight should be 1.1-1.2.
- reduce excessive nonfiber carbohydrates, which can lead to rumen acidosis
- evaluate protein levels
- evaluate trace mineral levels: copper is essential for the production of healthy horn, as well as zinc
- evaluate vitamins: vitamin A, beta-carotene, vitamin E and biotin are essential to healthy horn tissue
- feeding management: evaluate feeding frequency, particle size of forages and grains, transitioning animals onto different diets, first calf heifer transitioning into the milking herd
Behavior and stress Dairy cows should be allowed to lie down 10-14 hours per day. Well designed housing is essential to ensuring this. Exercise helps stimulate blood flow through the feet and keeps the tissues healthy. Manage first calf heifers differently than older cows to reduce the risk of laminitis. Stall comfort Adequate stall space and soft bedding are essential to ensuring that cows will utilize the stalls provided and lay down for 10-14 hours a day. Hoof Trimming Proper foot trimming is the only means to correct the problems of overgrown claws. Trimming done twice to three times a year will reduce lameness problems and detect lesions in the early stages of disease. The objectives of trimming are to shorten the toe and lower the outer hoof wall in order to shift the body weight from the heel bulbs to the toe and outside wall, scoop out the sole so the weight is put on the outside walls and not the soles, and balance the heels so each hoof has the same depth of heel and hoof wall appearance. 
Note the long hoof wall and swollen coronary band and pastern of the lateral (outside) claw on the left hind limb. Radiographs of this foot revealed lysis (destruction) of the pedal bone, most likely secondary to bone infection.
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