Limping cattle are a sight no producer wants to see, but the underlying issue might be caused by an infection. Finding the culprit to blame is just part of the battle in the fight against lameness.
By: Russ Daly, Extension Veterinarian, SDSU Extension
What are the processes that contribute to these cases of lameness? One way to classify the various cause of lameness in cattle is to group them into two different categories: bacterial infection and injury. Some lameness cases will bridge these two classifications: sometimes lameness-causing infections are the direct result of injuries. This article will focus on causes of lameness associated with infections.
Footrot is perhaps the most common infectious cause of lameness in feedlot and pasture cattle. The technical term for footrot is "infectious pododermatitis". Loosely translated, this means "inflammation of the skin and deeper tissues in the area of the hoof". Footrot is usually caused by the bacteria Fusobacterium necrophorum, but other bacteria can be involved as well. All of these bacterial species are commonly found in soil and animal manure. This infection involves the area between the toes rather than the hoof itself. When the protective barrier of the skin is breached by these bacteria due to constant wet conditions or by abrasions, the bacteria causes a painful, necrotic infection between the toes.
Hairy Heel Warts
If footrot is the most common infectious cause of lameness, hairy heel warts are the lameness cause getting the most recent attention in beef cattle circles. Hairy heel warts ("papillomatous digital dermatitis" is the medical term) have long been recognized as a significant problem in dairy cattle, but in recent years the problem has manifested itself in feedlot cattle as well. This is a very contagious condition, but how the disease starts in an animal is a bit unclear. Bacteria in the spirochete family can be demonstrated in the characteristic warts of this disease, but there may be other factors that enable the infection to take hold.
Any of the joints of the bovine limb potentially could harbor joint infections; however the most common joint affected by infection is the coffin joint—the lowest joint of the limb right at the hoof wall. Penetrating foreign objects can cause infection here, but a more common cause of coffin joint infections in cattle is a footrot infection that is not adequately treated. Infection spreads from the space in between the toes to penetrate the joint.
An infectious agent often associated with joint infections is Mycoplasma bovis. In feedlot calves, this bacteria typically enters the bloodstream following an infection in the lungs, where it may have been the cause of signs of respiratory disease or may have been subclinical. While swollen, painful joints are apparent outwardly, Mycoplasma bovis actually infects the structures around the joints such as tendon sheaths rather than the joint space itself.
Toe abscesses are the result of infection; however they occur in response to an insult to the tips of the toes. Abrasions and wearing away of the tips of the toes can happen in groups of excitable calves that have been handled on rough concrete, such as during loading and unloading trailers or processing. Infection and abscess formation occurs when environmental bacteria enter the underlying tissue of the toe after these insults.
A closely related problem, toe ulcers, probably has more to do with dietary influences than injury. This occurs when there is bleeding and infection in the "white line" area of the toe—where the hoof wall meets the sole. Subclinical acidosis, which may occur when calves are on high concentrate rations, is the potential cause of this syndrome.
Along that line, acidosis –whether obvious or subclinical -- is a major contributor to laminitis in feedlot calves, as well as occasionally in adult beef cattle. Acute lameness due to laminitis occurs due to the pain involved when the connection between the hoof wall and the underlying bone weakens and the structures begin to separate. Acute laminitis in cattle is not an infection; rather it is typically the result of a mistake in feed delivery or an accidental exposure to a level of grain to which the animal’s system is unaccustomed.
Infections are among the most common reasons for lameness in feedlot and adult cattle and in some cases can be treated or prevented with more success than other causes of lameness.