The role of the professional claw trimmer has changed significantly during the past decade. The introduction of chute-side computerized data collection is providing valuable data; however, it also requires additional training in lesion identification. Close collaboration between trimmer and veterinarian is beneficial for both and for the dairy industry overall.
Over time, the claws of cows wear, changing the shape of the sole, which in turn makes the foot unstable. The two claws become unbalanced both longitudinally and laterally. As changes occur in the lateral claw, it becomes “overloaded,” the heel horn may become thicker (overburdened), and posture is compromised. Therefore, the objective of trimming is to reduce excessive weight bearing on load-bearing claws.
Under normal circumstances, horn growth keeps pace with wear. The growth/wear rate at the heel is greater than at the toe. Horn that is dry tends to be extremely resistant to wear and may grow longer than normal. Thus, the claws of cattle maintained in straw yards tend to become overgrown. Conversely, the claws of cattle maintained in extremely wet conditions are softer than normal and more prone to wear and damage. If the cows are housed on concrete surfaces, the lateral hind claw tends to wear less than the medial.
If claws are routinely correctly trimmed, longevity of the herd may be extended. Trimming can be expected to decrease milk yield by up to 2 lb/day for 2 days but should be restored or even increase in a similar period. Decrease in milk yield is partly due to disruption in the cow's feeding routine and handling. To some extent, variations in milk yield reflect on the skill of the trimmer. Trimming should be avoided in any location close to the milking parlor, and individuals handling the cows should never attempt trimming. Unskilled claw trimming will negatively affect the claw health of a herd and should be avoided. All claws should be evaluated before trimming. On average, the front (dorsal surface) wall of a hind claw measures ~7.5 cm long from apex to hair line. When the dorsal wall increases in length, the dorsal surface of the claw tends to become concave (buckles like the instep of a human shoe). This causes greater weight-bearing to be transferred to the posterior aspect of the claw, increasing pressure on the flexor process of the distal phalanx, the point beneath which sole ulcers develop. The longer the toe, the greater the stress on the flexor system. When the claws are short and the dorsal wall is >7.5 cm, there is considerable risk that the thickness of the sole at the apex will be less than the desirable 7 mm. Thinning of the apex of the sole of short-clawed animals should be avoided.
Foot trimming of every cow in a high-production, intensively managed herd is recommended every 5 mo. Recording and reporting (to the veterinarian) the types of lesions observed will prompt early treatment and timely introduction of preventive measures.
Last full review/revision September 2015 by Paul R. Greenough, FRCVS