Beef cattle lameness: diagnostic strategies
One of the most common problems presented to bovine practitioners is lameness. In many cases the lameness is chronic because it is common for beef producers to treat lameness problems with antimicrobials before presenting the animal to a veterinarian. Antimicrobial therapy usually will cure most cases of simple foot rot, and time will heal many minor injuries. So when a lameness case is presented that already has been treated without success, it is usually a more serious problem. An accurate diagnosis is required to determine a prognosis and make economical treatment or culling decisions.
Most lameness originates from problems in the foot (approximately 95 percent in rear and 99 percent in forelimb). Obviously, if swelling is present in the foot area, then this can be examined first. But because restraint techniques used to examine adult bovine feet (lifting legs in a chute, tilt tables, casting in the field, etc.) can cause further injury to upper limbs if that is the origin of the problem. I prefer to rule out upper-limb lameness before concentrating on the foot if no swelling is present.
Although shoulder and knee injuries are common lay diagnoses, these areas are rarely a problem. Disuse atrophy of muscles of the proximal forelimb from a forefoot problem can make the point of the shoulder more prominent, but this should not be confused with a swelling in this area. Also, the normal slight carpus valgus confirmation of cattle can make the carpus appear swollen at some angles of observation. Careful palpation of the upper forelimb, carpus and fetlock should rule out major problems in the upper limb.Rear-limb lameness can be more difficult to differentiate. Stifle injuries are the second most common cause of lameness following feet problems. It is very important to diagnose these injuries prior to more involved restraint techniques because struggling of the animal can further damage this joint, turning a mild injury with a fair prognosis into a severe injury with a poor prognosis. It is common for cattle with stifle injuries, particularly cranial cruciate ligament injuries, to walk up on the toe with the heel elevated. Crepitus in the joint may be palpated during walking in gentle animals or with manipulation in a chute. Swelling of the stifle area and/or a drawer sign also are indicative of a stifle injury. Cattle with upper limb injuries are reluctant to kick, so kicking usually eliminates an upper-limb lameness and indicates a foot problem.
Once upper limb problems are ruled out, careful examination of the foot is indicated. Determining if one or multiple limbs are affected is important, as some diseases, such as laminitis, can affect more than one foot at times. Sometimes the effected limb will be abducted, indicating a lateral claw problem, or abducted, indicating a medial claw problem. Some problems are easily diagnosed from visual inspection, but diseases of deep structures can require further diagnostic techniques.
Hoof testers Hoof testers can be very helpful in determining if lameness originates in the foot and which particular claw is affected. However, at times, responses to hoof testers can be difficult to interpret. Animals might move because they are uncomfortable, especially when restrained on a tilt table, and the movement often coincides with applied pressure of hoof testers. Also, animals that are excited may not respond to hoof testers, even when major lesions, like coffin-bone fractures, are present.
Four-point nerve block If no abnormalities are found on examination and if no response is elicited with hoof testers, then a nerve block can be performed to completely rule out foot lameness. The four-point nerve block anesthetizes an area from the pastern distally. It might not completely block out the lameness, but if significant improvement is seen, then the foot should be evaluated further with radiographs. To perform the procedure, insert a 20-gauge, 1-inch needle into the dorsal aspect of the pastern, in the groove between the proximal phalanges, just distal to the fetlock. Administer 5 mls of lidocaine deep, and another 5 mls superficially. This injection is repeated on the palmar/plantar aspect of the pastern, just distal to the dewclaws. Next, palpate the nerve over the lateral aspect of the fetlock, approximately 2 cm dorsal and proximal to the dewclaw. Administer 5 mls of lidocaine over the nerve and repeat on the medial side.