While we usually think of foot problems in feedlot calves occurring in conjunction with warm, muddy conditions, wintertime also brings a certain set of conditions that can create lameness in these animals.
Foot rot (technically, “interdigital necrobacillosis”) is a frequent complaint among feedlot populations, even in wintertime. Foot rot is caused by one of two species of bacteria—Bacteroides nodosus, and Fusobacterium necrophorum, both of which are present essentially everywhere in the environment of the feeder calf. These bacteria need a way to penetrate the skin of the bovine foot between the toes. Once they do, they invade the deeper tissue, causing a uniform swelling in the foot right above the hoof, significant lameness, and a foul-smelling wound between the toes.
Since these organisms are extremely common in mud and manure, their method of penetrating the skin becomes the most important factor to manage in outbreaks of foot rot. In wintertime, the most common way this penetration occurs is the abrasion that occurs when calves step on frozen chunks of manure in the feedlot. In warmer conditions, this penetration most often occurs due to constant exposure to moisture (standing in mud or water) breaking down the skin’s normal defenses.
Prevention of foot rot during the winter months should take the form of eliminating sharp frozen spikes of manure in the lot, possibly by use of box scrapers or other implements. Vaccines are available against F. necrophorum and B. nodosus, and may help cut down (but not eliminate) the number or severity of foot rot cases.
Cases of foot rot normally respond well to systemic antibiotic treatments. However, since there are several other causes of lameness in feedlot cattle, it’s important to differentiate between foot rot (treatable with antibiotics) and other conditions (not responsive to systemic antibiotics). Some of these other conditions include:
• Toe abscesses. The signs of lameness due to this phenomenon become apparent roughly a week after cattle enter a feedlot. Often this occurs when flighty groups of calves are moved through facilities with rough concrete floors, where speed of the calves and lack of traction result in abrasions to the tip of the toes. Infection and severe lameness result. Treatment with antibiotics is unrewarding, but opening the abscesses with a hoof knife and establishing drainage often resolves the problem.
• Laminitis, or “founder”. Occasionally disruptions or miscalculations in feeding result in laminitis, a condition where the connection between the hoof wall and the underlying bone separate. Removal of these animals to softer bedding may help manage pain until it subsides. In chronic cases, excessive hoof growth will occur in these animals, further complicating their locomotion.
• Hairy heel warts. Typically associated with dairy populations, this is an infection caused by bacteria different from those causing foot rot. Raw, circular areas between the bulbs of the hooves on the back of the foot are the tell-tale sign of this infection. Injectable antibiotics are ineffective against heel warts, but topical treatments may help.
• Joint infections. Mycoplasma bovis is among the bacterial infections that can cause joint infections in feedlot cattle. These are usually unresponsive to antibiotics and often occur several weeks after a respiratory disease outbreak.
Examination of the feet of lame animals will go a long way to determine which of the various causes of feedlot lameness are present, and to determine the best course of treatment. Advice from a veterinarian should be included when making any decisions about diagnosis and treatment of feedlot lameness conditions.