Wear of orthopaedic hoof blocks under New Zealand pasture conditions.

Introduction
Claw horn lesions are the most important reason for lameness^1,2 and can be treated effectively by therapeutic trim and elevation of the diseased claw using an orthopaedic block³. There is a large range of commercial hoof blocks available but data are limited on their suitability for cows kept in a pasture-based system where walking distances can be significantly longer than in indoors systems⁴. The objective of this study was to investigate the performance of three commercial block products with regard to the pattern and rate of wear in New Zealand pasture-based dairy cows. 

Materials and Methods
Farmer presented, Friesian and Friesian x Jersey dairy cows, with a unilateral hind limb lameness due to a claw horn lesion were randomly allocated to treatment with one of three blocks: 1) plastic shoe (CowSlip); 2) wooden (Bovi-Bond) or 3) foam (Walkease). Blocks were checked during milking by the farmer (present/ not present) and date of loss was recorded. Measurements of block depth were obtained on day 14 and day 28 after block placement. For each block type a reference block was used to identify six fixed landmarks – outer toe (OT), inner toe (IT), outer centre (OC), inner centre (IC) , outer heel (OH)and inner heel (IH). Depth measures were taken with electronic callipers at the landmarks on the block used for treatment. Blocks were removed on day 28 unless further elevation of the diseased claw was clinically indicated. Data were analysed for each block type using a linear repeat measures mixed models with depth at each site as the outcome variable and claw blocked, visit and their interaction as the dependent variables.  […]