Gait (locomotion) scoring is recommended as a way to identify lame cows that should be examined to determine the cause of their lameness. Dairy cow lameness is primarily caused by joint injury or by a hock or claw lesion. How reliable is gait scoring in identifying claw lesions?
To investigate the association between locomotion score and the presence of hoof lesions, researchers examined 10,699 cows from 91 dairy herds in southern Chile. Locomotion score was recorded on a scale of 1-5 using the Sprecher system described here. Lesions were recorded by observation of all four feet with each cow standing in a metal crush.
The graph below illustrates the percentage of cows having various lesions in relation to their locomotion score. The presence of sole ulcer or double sole was associated with increasing locomotion score (more severe lameness). In contrast, the presence of other lesions was not associated with increasing gait score suggesting that locomotion scoring is not an effective strategy for identifying cows afflicted with several important claw lesions.
The bottom line is that the method of locomotion scoring used here was relatively insensitive for the detection of some important claw lesions. This result is in agreement with those of earlier studies. A Swedish study showed that, among cows with claw disorders (72%), only a small percentage was diagnosed as clinically lame (5%). A similar study in the Netherlands (referred to here) showed that less than 1% of cows with affected claws were lame.
The authors of the present study discuss the relevance of these results:
“Does it matter if a cow has a lesion and is not lame? Is the presence of any lesion an abnormality? Lesions may resolve and never cause lameness and there is no need to concern ourselves with lesions that do not cause lameness. However, it may be that treatment of lesions in non-lame cows prevents them from becoming lame. It might also be that the locomotion score is insufficiently sensitive and that these lesions are causing the cows discomfort, but not sufficient discomfort to change their gait (it takes effort and energy to walk abnormally and so a change in gait will only be made when it is less costly than maintaining normal gait).”
source: N. Tadich, E. Flor and L. Green. The Veterinary Journal 184:60 (2010) – full article here.