Physical Examination of a Lame Cow
Abrasions or swellings on the limbs suggest a prior traumatic event. Decubital lesions (to the knee or more often the hock) might indicate prolonged periods of recumbency or difficulty when rising. Cubicle design should be reviewed. Muscular atrophy, particularly noticeable in the gluteal region, can be associated with a painful condition such as arthritis. Cows experiencing extreme pain can lose body condition rapidly.
Stance or posture can change as the bearing surface of the claw wears or there is a painful lesion in the foot. In a normal stance, the point of the hock (tuber calcanei) lies directly beneath the pin bone (ischial tuber) when viewed either from the side or from behind. Approximately 60% of the body weight is borne by the forelimbs. A lame animal adjusts its posture to relieve pain.
The following principles illustrate specific examples of changes in stance or posture related to lameness: 1) A painful abscess in a lateral hind claw causes the cow to abduct that limb. 2) Pain in the heel of the hind foot forces the cow to hold its foot to the rear, a posture known as “camping back” or retraction. 3) After a cow has spent much time walking on concrete, the lateral hind claw may become overburdened (excessive buildup of solear horn). This forces the hock to turn inward, a posture referred to as “cow hocked. ” 4) Pain in the toe, which occurs in laminitis, causes the cow to hold its hind feet further forward than normal, a posture referred to as “camping forward” or protraction. This posture can be confused with a conformational defect referred to as “sickle hock,” in which the angle of the hock is <160º. 5) When the angle of the hock is <180º, the posture is referred to as “post leg,” an undesirable conformational characteristic associated with arthritis. 6) When the hind feet are held closer together than normal (adducted), pain in the medial claw is indicated. The cow is said to be “standing narrow.” This posture is often confused with a trait of conformation called “bow leg.” Standing narrow can be a sign of laminitic-related lesions in the medial claw .
These principles of abnormal posture can be used to deduce the region of the foot in which the seat of lameness is located. Use of hoof testers may be one way to confirm the observation. For example, if there is pain in the toe, the retraction phase of the stride (when the foot passes behind the phase of vertical weight-bearing) is reduced considerably. In contrast, if there is pain in the heel, the protraction phase of the stride is reduced, or the foot is not carried as far forward as normal. Usually, the gait of one limb can be compared with that of the contralateral limb when viewed from the side. However, lameness simultaneously present in contralateral limbs tends to appear less severe than is actually the case. It is not unusual in cases of subacute laminitis for all limbs to be affected more or less equally. In these cases, no specific gait change is seen, but the cows tend to place their feet carefully with each step, ie, they “plod” or have a stilted gait.
In cows exposed to concrete surfaces for a prolonged period, the sole of the lateral claw is likely to be worn flat and become much wider than that of the medial claw. Such soles are highly subject to trauma.
To facilitate examination of a completely flat claw, the surface of the sole should be washed and examined carefully for black marks by exploring with a hoof knife. If the sole is heavily caked with mud or manure (eg, cows at pasture or confined in corrals or straw yards), it is quicker and easier to cut off a layer of superficial horn together with the caked material to expose fresh horn beneath. Particular attention should be paid to the abaxial white line area. Removal of large amounts of sole horn is contraindicated in the diagnostic phase of an examination. The interdigital space should be evaluated by separating the claws and examining carefully for evidence of a foreign body, fibroma, footrot, interdigital dermatitis, or digital dermatitis.