New Insight into the Prevalence and Risk Factors for Three Distinct Hoof Conformation Traits in UK Commercial Sheep Flocks

Abstract

Lameness in sheep continues to be a global health, welfare and economic concern. Damaged, misshapen or overgrown feet have the potential to cause lameness either directly, or indirectly. There is a lack of understanding of the predisposing factors for different hoof conformation traits in sheep. Our exploratory study aimed to investigate the prevalence of, and risk factors for, three distinct hoof conformation traits relating to the sole and heel, hoof wall, and hoof wall overgrowth. Feet of 400 ewes from four UK commercial sheep farms were inspected at four time points across 12 months. For each conformation trait, a four-point ordinal system was used to score each individual claw, and foot-level scores were calculated. We present 92.4% of foot-level observations to be affected by ≥1 conformation traits. Whilst hoof conformation traits were correlated to some degree, a unique set of sheep-, foot- and farm-level factors were associated with each distinct conformation trait. We provide, for the first time, key insight into the multifaceted and multifactorial aetiology of hoof conformation in sheep, building upon previous landmark studies. Our results inform hypotheses for future prospective studies investigating the risk factors for adverse hoof conformation in sheep.

Keywords: damaged; hoof conformation; lameness; misshapen; overgrown; prevalence; risk factors; sheep.

Figure 1

(a) Front foot with an undamaged sole and heel area and perfect shape (Foot-level score for sole and heel conformation = 0); (b) Front foot with a severely damaged sole and heel area of the medial claw (Foot-level score for sole and heel conformation = 3).

Figure 2

(a) Back foot with an undamaged hoof wall and perfect shape (Foot-level score for hoof wall conformation = 0); (b) Back foot with a severely misshapen and damaged hoof wall of the medial claw, and a moderately damaged lateral claw (Foot-level score for hoof wall conformation = 5).

Figure 3

(a) Front foot with no hoof wall overgrowth present (Foot-level score for hoof wall overgrowth = 0); (b) Back foot with severely overgrown wall covering ≥ 75% of the sole of both claws (Foot-level score for hoof wall overgrowth = 6).

Figure 4

Mean foot-level conformation scores by visit for 5672 foot-level observations of 400 ewes. Visit 1: September 2019; Visit 2: January 2020; Visit 3; July 2020; Visit 4: September 2020. Error bars represent SEM.