Foot rot in grazing cattle
Foot rot is a subacute or acute necrotic (decaying) infectious disease of cattle, causing swelling and lameness in one or more feet. The disease can become chronic, with a poorer prognosis for recovery if treatment is delayed, which results in deeper structures of the toe becoming affected.
Weight gain is significantly reduced when grazing cattle contract the disease. Foot rot is usually sporadic in occurrence, but the disease incidence may increase up to 25 percent in high-intensity beef or dairy production units. Approximately 20 percent of all diagnosed lameness in cattle is actually foot rot.
Mechanical injury or softening and thinning of the interdigital (between the toes) skin by puncture wounds or continuous exposure to wet conditions are necessary to provide entrance points for infectious agents.
Fusobacterium necrophorum is the bacterium most often isolated from infected feet, but is also frequently isolated from non-diseased interdigital skin.
The majority of F. necrophorum isolated belong to biotypes A and AB which produce toxins that cause necrosis (decay) of the infected tissues. F. necrophorum is also isolated from liver abscesses in feeder cattle, necrotic stomatitis in calves, and calf diphtheria.
F. necrophorum appears to act cooperatively with other bacteria, such as Bacillus melaninogenicus, Staphylococcus aureus, Escherichia coli, and Actinomyces pyogenes, thereby decreasing the infective dose of F. necrophorum necessary to cause disease.
Bacteroides nodosus, the organism causing foot rot in sheep, may cause an interdigital skin surface infection in cattle, allowing entrance of F. necrophorum and thereby causing foot rot.
Feet infected with F. necrophorum serve as the source of infection for other cattle by contaminating the environment.
Estimates on the length of time F. necrophorum can survive off of the animal, range from one to ten months. Once loss of skin integrity occurs, bacteria gain entrance into subcutaneous tissues and begin rapid multiplication and production of toxins that stimulate further continued bacterial multiplication and penetration of infection into the deeper structures of the foot.
Besides clinical signs, the article also covers treatment and prevention measures. The article mentions that the most important preventive measures are centered on the protection of interdigital skin. The table also shows the effects of zinc methionine on gain and incidence of foot rot in grazing cattle.
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Article made possible through the contribution of the Oklahoma State University, Oklahoma Cooperative Extension Service.