Herd and cow-level prevalence of sole ulcers in The Netherlands and associated-risk factors.

A cross-sectional study was performed, to (re)evaluate the prevalence of sole ulcers (SUs) and the risk factors involved in dairy herds that perform claw trimming on a routine base. Twenty hoof trimmers collected data on the presence or absence of claw disorders on the hind claws of dairy cows during whole herd trimming in 383 herds in The Netherlands. A questionnaire was used to acquire information on management and housing. Additional data on parity, breed and stage of lactation of the cows were provided by the Dutch Herd Book Organization. Sole ulcer was present in 85% of the herds and in 5.6% (S.E. 0.2) of the study population (n=22,454 cows). The within-herd prevalence varied from 0% (14.6% of herds) to 26% (0.3% of herds) and in herds with SU was most frequently diagnosed 1-5% of the trimmed cows (45% of all herds). The risk for SU increased significantly with increasing parity. Cows that were at or after peak of lactation (>60 days in milk, DIM) had higher odds on SU in comparison to cows that were between 0 and 60 DIM (OR=0.6). The presence of other non-infectious claw disorders appeared to predispose to SU. Based on an estimation of the population attributable fraction, it was concluded that if sole hemorrhages, chronic laminitis (CL), white line disease and interdigital hyperplasia were the cause of SU and if those diseases could have been prevented in the study population, 35.4, 5.8, 11.6 and 4.6% of the SU cases respectively could have been prevented. Because of this relation, an effective intervention strategy of SU should focus on an integral approach of reducing the first stages of the bovine laminitis complex, whereas SU and CL are considered to be a later stage. Cows trimmed during late summer were at a higher risk for SU than cows trimmed in other periods of the year. Finally, cows in herds with purchased heifers were at a higher risk (OR=1.4) for SU than cows in herds that did not purchase heifers. A comparable positive effect was visible in herds with mattress bedding.