Toe Tip Necrosis Syndrome (TTNS) is a debilitating disease affecting the lower hind limb of cattle characterized by necrotic bone, wear or rounding of the hoof and breakdown of the white line region. This breakdown is thought to be the cause of TTNS, though this is unclear. The overall aim of this research was to investigate the hypothesis that mechanical damage and loading is the cause of the white line separation, which could ultimately lead to TTNS.

Objective 1 of this research aimed to identify if loading is associated with white line separation and subsequently TTNS. Eleven diseased specimens and ten healthy specimens were loaded in a materials testing system against an acrylic plate. A camera, located underneath the hoof, imaged the apical region to identify the area of white line separation. Specimens were imaged using a High-Resolution Peripheral Quantitative Computed Tomography (HR-pQCT) scanner with a contrast agent to assess the volume of separation. Objective 2 investigated whether mechanical damage under a fatigue loading regime would induce white line separation. Ten healthy pairs of specimens were tested (10 healthy, 10 with simulated damage) under fatigue loading for 36,000 cycles at 1000 N.

The results from Objective 1 indicated a positive association between loading and white line separation in diseased hooves. However, healthy hooves showed no separation. These findings support the hypothesis that mechanical loading is involved in TTNS etiology or disease exacerbation and acceleration.

Findings from Objective 2 indicate no association between cycle count and white line separation. These results suggest that white line separation (and subsequent TTNS) may not be due to wear or prolonged repetitive loading. These results indicate that another loading parameter or a biological event likely initiates white line separation and ultimately TTNS.