Curative claw trimming for mechanical relief of sole ulcers - an ex-vivo study

Abstract

Overloading or excessive mechanical stress to the claws may damage the sensitive claw tissues and subsequently lead to sole ulcers. Corrective treatment can prevent complications of these sole ulcers. The aim of this study was to investigate the effects of a wedge-shaped relief incision from the bulb to the tip of the outer claw of the pelvic limb on the pressure distribution beneath the pertaining claw. Furthermore, it aimed to clarify whether a change in the pressure distribution would lead to dermal pressure relief in the area of a horn defect. Nineteen isolated bovine limbs from an abattoir were gradually trimmed resulting in following stages. A: initial condition; B: functional claw trimming, steps 1-3; C: extension of the model and drill of a circular lesion at the Rusterholz site (outer claw ulcer simulation); D: wedge shaped, weight-relieving incision from the bulb halfway towards the sole tip; E: further extension of the wedge-shaped incision towards the sole tip. The limbs were loaded with 200 kg following each of the procedures. A pressure sensor system was used in order to analyze the pressure distribution beneath the claws. Furthermore, positioning of the claws on a glass plate allowed for an evaluation of corium resp. fat cushion protrusion through the artificial lesion. In the untrimmed claws, an average of 63 % of the total force applied rested on the outer claw area. This value decreased to 30 % following step E. Maximum pressure values shifted from the bulb area towards the sole tip with increasing degree of claw trimming. The relative loading area of the inner claw increased to up to 18.4 % following the procedures. The described incision technique (step E) resulted in a significant reduction of corium protrusion through the artificial horn defect in comparison to the claw situation in step C. The wedge-shaped, weight-relieving incision (step E) led to pressure reduction in the area of the outer claw and the bulb region in this ex-vivo-study. Therefore, this trimming method may serve to relieve pressure from the vulnerable Rusterholz site as well as providing means for reducing corium compression. The described trimming method facilitates pressure relief on the outer claw area in live animals. In this, it may exert a positive effect on disease progression in Rusterholz sole ulcers.