Testing White Line Strength in the Dairy Cow

Prevalence and Temporal Dynamics of White Line Disease in Sheep: An Exploratory Investigation into Disease Distribution and Associated Risk Factors

Lameness in sheep is a global health, welfare and economic concern. White line disease (WLD), also known as shelly hoof, is a prevalent, non-infectious cause of lameness, characterised by the breakdown of the white line. Little is known about the predisposing factors, nor the individual disease dynamics over time. Our exploratory study aimed to investigate the prevalence and temporal dynamics of WLD, and the associated risk factors. Feet of 400 ewes from four UK commercial sheep farms were inspected for WLD at four time points across 12 months. The change in WLD state at foot-level (develop or recover) was calculated for three transition periods. We present WLD to be widespread, affecting 46.8% of foot-level and 76.6% of sheep-level observations. States in WLD changed over time, with feet readily developing and recovering from WLD within the study period. The presence of WLD at foot-level, the number of feet affected at sheep-level and dynamics in development and recovery were driven by a variety of foot-, sheep- and farm-level factors. We provide key insight into the multifaceted aetiology of WLD and corroborate previous studies demonstrating its multifactorial nature. Our study highlights an opportunity to reduce WLD prevalence and informs hypotheses for future prospective studies.

Investigation of white line separation under load in bovine claws with and without toe-tip necrosis

OBJECTIVE

To compare the degree of white line separation created by increasing physiologic loads between bovine claws with and without toe-tip necrosis (TTN).

SAMPLE

Cadaveric bovine hind limbs with (n = 10) and without (10) TTN.

PROCEDURES

Hind limbs in which 1 or both claws had evidence of apical white line separation were considered to have TTN. Hind limbs in which neither claw had evidence of white line separation were considered controls. Each hind limb was mounted in a materials testing system with the bottom surface of the hoof angled at approximately 5° to the horizontal plane such that the apex of the claws made initial contact with the clear testing surface to simulate physiologic loading conditions. A digital camera mounted underneath the testing surface was used to obtain images of the bottom of the hoof during the application of each of 3 increasing static loads (1, 2, and 3 kN). The images were analyzed with commercial image-processing software to quantify white line separation area.

RESULTS

White line separation area was significantly greater for claws with TTN than for control claws and increased as the applied load increased. White line separation was almost nonexistent in control claws and was not affected by increasing load.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that mechanical loading exacerbated TTN, but compressive loading alone, even at excessive levels, did not initiate the condition. Interventions (eg, hoof blocks) that decrease loading of affected claws may be beneficial for the treatment of TTN at its earliest stages.

Modulus of elasticity and dry-matter content of bovine claw horn affected by the changes of chronic laminitis

The mechanical properties of horn samples from 22 hind claws with chronic laminitis were determined in adult Austrian Fleckvieh cows. The resistance to deformation was quantified as the modulus of elasticity (E). Tension tests revealed mean E values of 520MPa for the dorsal wall, 243MPa for the abaxial wall, 339MPa for the axial wall and 97MPa for the sole. E tended to be lower in laminitic horn than in sound horn in all segments tested, with the difference being largest in the abaxial wall. The mean dry-matter content (DMC) of the laminitic claws was 75.8% in the dorsal wall, 75.86% in the abaxial wall, 71.15% in the axial wall and 69.28% in the sole. These values are generally comparable to those for sound claws except in the axial wall. Further, E and DMC were only correlated in the axial wall. Chronic laminitis leads to a low resistance of claw horn to mechanical insults in the dorsal wall, abaxial wall and sole, and to the loss of a correlation between the E and DMC in these segments. The reason for these alterations is therefore not increased ingress of moisture, but must be due to changes in the microstructure, biochemical components and/or horn formation by the diseased dermis.