Measurements of claw dimensions in cows before and after functional trimming: a post-mortem study

The aim of this study was to compare measurements of the medial and lateral claws of the hind feet in cattle, and to establish reference values to aid in functional claw trimming. Variables of the medial and lateral claws of 40 hind feet obtained from 40 slaughtered German Simmental cows were measured. To standardise the observations the soles of both the medial and lateral claws were first trimmed to a defined thickness of 5mm at the apex and 8mm at the heel, before measurements were taken. After this standardisation, the mean lengths of the dorsal walls of the two claws were not significantly different (means, lateral 76.8, medial 77.1 mm). However, there were considerable other differences. For example, the soles of the lateral claws were significantly (P < 0.01) longer (means, 120.1mm versus 112.7 mm, and wider (means, 52.0 mm versus 42.5 mm). In 36/40 feet, the sole of the lateral claw protruded approximately 2-3mm above the sole of the medial claw after the standardisation. The soles of the lateral claws were therefore then trimmed to the height of the medial claw ("levelling") and the measurements were repeated in the lateral claws. The dorsal wall of the lateral claw was then significantly shorter than that of the medial claw (means, 74.8 mm versus 77.1 mm) and, most importantly from a functional point of view, the sole was significantly thinner than that of the medial claw (means, 2.71 mm versus 5mm at the toe tip, 4.9mm versus 8 mm at the heel). Finally, the horn capsule of all claws was removed and various measurements of the corium surface were made. The length of the dorsal corium surface did not differ statistically (P > 0.05) between the lateral (mean, 62.6 mm) and medial (mean, 62.5 mm) claws. Strict adherence to the principles of functional trimming thus reduces the thickness of the sole, the length of the dorsal wall and the length and height of the bulb of the lateral claw. This suggests that the sole of the medial claw should be left an extra 3 mm thicker than previously recommended such that, after "levelling", the sole of the lateral claw remains thick enough to protect fully the corium and the claw retains a more normal shape.     

Ultrasonographic measurement of the sole horn thickness in bovine claw

Ultrasonographic thickness measurement and imaging of sole horn and the encapsulated soft tissue layers was evaluated in 100 bovine claw specimens. The claws were trimmed and examined in longitudinal planes using a 7.5 MHz linear transducer. In each claw, ultrasonographic measurements of horn thickness of sole and distance from outer claw surface to distal phalanx surface were made at three marked points on the weightbearing surface. All claws were then frozen, transected and anatomical reference measurements were made after thawing. The sole horn, corium, subcutis and distal surface of the distal phalanx of all claws were clearly visualized. The sole horn had a heterogeneous hypoechoic appearance, the underlying soft tissue layer was predominantly anechoic. Corium and subcutis could be differentiated. Best imaging of these structures was achieved in claws with less than 10 mm sole horn thickness and soft sole horn. Statistical correlation coefficients of 0.88 to 0.91 were found for ultrasonographic and anatomical measurements of sole horn thickness. Therefore, B-mode ultrasonography proved to be an accurate, non-invasive technique for measurement of the sole horn thickness in bovine claws.     

Prevalence of digital dermatitis in first lactation cows assessed at breeding cattle auctions

The prevalence of digital dermatitis (DD) in first lactation cows (FLCs) presented at 10 breeding cattle auctions was determined in a single auction centre in Austria over a period of 14 months. At each auction, FLCs were selected randomly for claw examination from the monthly auction catalogue. After obtaining owner consent, the hindclaws were examined in a walk-in crush. The type of lesion (M1–M4) and the diameter of DD lesions together with claw horn lesions and the trimming status of the claws were evaluated.From a total of 1110 FLCs registered for the ten auctions, 399 (36%) were randomly chosen for examination and 199 FLCs (17.9%) could be defined. In 63 cows (15.7%), the owners refused consent. A total of 24 FLCs were found to have DD lesions on one or both hindlimbs, resulting in a DD prevalence of 12.1%. The size of lesions ranged from 0.5–3 cm in diameter. No influence of environmental factors (such as season or housing) on the prevalence of DD could be found. In 30/199 (15.1%) of FLCs examined, claw horn lesions such as double sole, white line disease and sole ulcer were observed, but both claw horn and DD lesions were seen in only three cows. Potential buyers at auctions should be aware of both conditions, as the 12.1% prevalence of DD and the 15.1% prevalence of claw horn lesions in FLCs are considerable. Critical evaluation of claw health and DD is essential when purchasing breeding cattle.     

Ultrasound measurement of sole horn thickness in trimmed claws of dairy cows

OBJECTIVE: To determine whether ultrasound could be used to measure sole horn thickness in dairy cattle after claw trimming with an adaptation of the Dutch method. DESIGN: Case series. ANIMALS: 24 adult Holstein dairy cows. PROCEDURE: Cows were restrained in a standing position, and claws were trimmed with an adaptation of the Dutch trimming method. B-mode ultrasonography was then performed. The transducer was placed on the sole just caudal to the apex of the toe and immediately medial and parallel to the abaxial white zone. The inner margin of the sole was identified as a thin hyperechoic line. Soles were considered to be too thin if sole horn thickness, determined by use of ultrasonography, was < 5 mm. RESULTS: Sole horn, underlying soft tissues, and the distal surface of the third phalanx were imaged in 151 claws. The inner margin of the sole could not be identified in 4 claws, and 37 claws could not be imaged because cows collapsed in the restraining chute. Mean +/- SD sole thickness for all claws was 71 +/- 1.3 mm. Only 1 sole was < 5 mm thick. The lateral front claws were significantly thicker than the medial hind claws. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that ultrasound imaging can be used to determine sole thickness in dairy cattle after routine claw trimming.     

Functional and corrective claw trimming.

Foot care and claw trimming require proper systems for restraint, sharp knives and trimming equipment, and an understanding of the biomechanics of weight bearing and hoof overgrowth in cattle. The objective of functional claw trimming is to correct hoof overgrowth, thereby re-establishing appropriate weight bearing within and between the claws of each foot. Traditional trimming methods fail to achieve these objectives. Corrective trimming procedures are applied to horn lesions affecting the claw capsule. Primary objectives of corrective trimming are to adjust weight bearing to provide rest for diseased claws and to remove loose horn and hard ridges that may cause further injury to the corium. The application of a foot block to the healthy claw is a valuable aid in foot care when corrective trimming alone is insufficient to provide needed relief from weight bearing. Finally, the use of topical treatments under a bandage is controversial. It is recommended that caustic treatments be avoided and that the use of a bandage be limited to conditions requiring hemostasis or when operators are committed to their removal within a period of 2 to 5 days depending on the level of environmental contamination.     

Measurements of forelimb claw dimensions in cows using a standardised sole thickness: a post-mortem study

Measurements of both front feet of slaughtered German Simmental cattle (17 heifers, 13 cows) were carried out to document the normal shape and size of the forelimb claws and to gain information about function and possible predisposition to disease. Only clinically normal feet were examined, and a standardised sole thickness of 5mm at the tip and 8mm in the heel region in both claws was established as a reference. The dorsal wall length, dorsal wall angle, heel length, height and width, sole and claw length and claw width, sole circumference and sole area were measured. After removal of the horn capsules, measurements of values at the level of the corium were carried out. The lateral front claws were wider and the medial claws longer than their partner claws. Overall, the sole surface areas and circumferences of the paired claws were similar, but were statistically larger in the medial claws. The front claws were characterised by long and high heel bulbs, and had a toe length:heel bulb length ratio of approximately 1.6:1. These properties, together with the musculo-tendinous attachment of the limbs to the trunk, are believed to provide better protection for the forelimb claws when standing or walking on hard surfaces. Functional mechanical relief of the medial front claws is probably best achieved by pairing the soles of the foot to the same level, which usually entails reduction of the lateral claw. For German Simmental cattle, a dorsal wall length of 75mm can be used as a guideline when trimming front and hind feet.     

Association of claw disorders with claw horn colour in norwegian red cattle - a cross-sectional study of 2607 cows from 112 herds

Claw disorders cause problems in dairy cattle all over the world. Nutrition, feeding, environment, claw trimming routines, hormonal changes related to calving and genetics are among the factors which influence the pathogenesis. The colour of the claw horn (pigmentation) has been suggested to play a role. The aim of this study was to investigate if there were any associations between the colour of the sole horn and claw disorders detected at claw trimming. Altogether, 2607 cows on 112 farms were claw trimmed once and the colour (dark, mixed or light) of the right lateral hind claw and hind claw disorders were recorded by 13 trained claw trimmers. The data were analysed using logistic regression models with logit link function, binomial distribution and herd and claw trimmer as repeated effects, with herd nested within claw trimmer. Haemorrhages of the sole (HS) and white line (HWL) were more frequently found in light than in dark claws (OR = 2.61 and 2.34, respectively). Both HS (OR = 1.43) and corkscrewed claws (OR = 1.84) were slightly more prevalent among cows which had claws with mixed colour versus dark claws. There were no significant associations of other claw disorders with claw horn colour.     

Review of Pododermatitis circumscripta (ulceration of the sole) in dairy cows

Sole ulcers are among the most frequent causes of lameness in dairy cattle. They are found most commonly in the hind lateral claw, are frequently bilateral, and have a high rate of reoccurrence. The pathogenesis of sole ulceration is primarily based on mechanical injury by the 3rd phalanx to the corium, basement membrane, and basal layers of the sole epidermis as a result of failure of the suspensory apparatus in the claw. The main pathways in the failure of the suspensory system include inflammatory (dermal vascular changes followed by disruption of keratinocyte proliferation and differentiation caused by local and systemic mediators) and noninflammatory (hormonal and biochemical changes in the peripartum period resulting in alterations of connective tissue in the suspensory system) pathways. Sole ulcers tend to occur in specific locations; the most reported site is the junction of the axial heel and sole. Other locations include the apex of the toe and the heel. Varying degrees of lameness may result, and the most severe are seen with complicated cases in which ascending infection affects the deeper structures of the claw. Pathologic changes at the ulcer site include dyskeratosis and dilated horn tubules with microcracks. Vascular changes include dilatation and thrombosis of capillaries with "neocapillary formation." Areas of dyskeratosis may remain for as long as 50 days at the ulcer site. Treatment includes corrective trimming and relief of weight bearing. Complicated cases may require surgical intervention.     

Bovine sole ulcer: a literature review

Sole ulcers are the most frequently encountered lesion in lame cattle. They are of growing concern to the dairy industry since the incidence of ulcers is increasing. Ulcers cause financial losses, the animal's wellbeing is disturbed to a high degree and they harm the image of the industry in general. Biomechanic factors and laminitis are of particular significance in the pathogenesis of the sole ulcer. The development of sole contusions and ulcers is assumed to occur in 3 phases (Sinking theory). In the first phase there is a general disturbance in the vascular system of the corium. The second phase follows when the structures that suspend the claw bone within the horn shoe give way. The locus minoris resistentiae has yet to be identified. The claw bone sinks and causes various lesions when it pinches the underlying sole or heel corium. The third phase begins when haemorrhages become visible on the horn surface of the sole or when the sole ulcerates; socalled third phase lesions. The relationship between the development of sole ulcers and anatomical structures such as the claw bone's tuberculum flexorium or the fat bodies under the bone are unclear. Epidemiological studies have shown that sole ulcers have a high rate of recurrence. The healing processes and the factors that influence them have hitherto not been studied.     

Ultrasonographic Imaging and Thickness Measurement of the Sole Horn and the Underlying Soft Tissue Layer in Bovine Claws

Ultrasonographic imaging and thickness measurements of sole horn and underlying soft tissue layer were evaluated in 100 bovine claw specimens. The claws were trimmed and examined in longitudinal planes using a 7.5 MHz linear transducer. The sole horn, underlying soft tissue layer and distal surface of the distal phalanx of all claws were clearly visualized. The sole horn had a heterogeneous hypoechoic appearance; the underlying soft tissue layer was predominantly anechoic. Corium and subcutis could be differentiated. The best imaging of these structures was achieved in claws with less than 10 mm sole horn thickness and soft sole horn. Imaging of the dorsal wall structures was more difficult. In each claw, B- and A-mode measurements of horn thickness of sole and dorsal wall and distance from outer claw surface to distal phalanx surface were made at three marked points on the weightbearing surface and at one point on the dorsal wall. In 10 claws, CT-images were taken and the horn density was determined. All claws were then frozen, transected and anatomical reference measurements were made after thawing. Statistical correlation coefficients of 0.88 and higher were found for B-mode ultrasonographic and anatomical measurements of sole horn thickness. A-mode proved not to be useful for the sole horn thickness measurement. B-mode ultrasonography was carried out successfully in the claws of five living cattle.     

Genetic parameters for claw health and feet and leg conformation traits in Finnish Ayrshire cows

Genetic parameters for different claw disorders, overall claw health and feet and leg conformation traits were estimated for Finnish Ayrshire cows. The merged data set with records of claw health and feet and leg conformation traits consisted of 105 000 observations from 52 598 Finnish Ayrshire cows between 2000 and 2010. The binary claw health data and the linearly scored conformation data were analysed using an animal model and restricted maximum likelihood method by applying the statistical package ASReml. Binomial logistic models with mixed effects were used to estimate genetic parameters for sole haemorrhages, chronic laminitis, white‐line separation, sole ulcer, interdigital dermatitis, heel horn erosion, digital dermatitis, corkscrew claw and overall claw health. Estimated heritabilities for different claw disorders using a binomial logistic model ranged from 0.01 to 0.20. Estimated heritability for overall claw health using a binomial logistic model was 0.08. Estimated heritabilities for feet and leg conformation traits ranged from 0.07 to 0.39. The genetic correlations between claw health and feet and leg conformation traits ranged from ?0.40 to 0.42. All phenotypic correlations were close to zero. The moderate genetic correlation, together with higher heritability of feet and leg conformation traits, showed that RLSV (rear leg side view) is a useful indicator trait to be used together with claw trimming information to increase the accuracy of breeding values for claw health in genetic evaluation.     

A method of biomechanical testing the suspensory apparatus of the third phalanx in cattle: a technical note

There are a number of differences between the claws of the front and hind limbs in cattle concerning macroscopic shape, chemical and physical properties of claw horn and epidemiological data. Front claws have superior data in almost every respect. Virtually no information is available on the mechanical stability of the suspensory apparatus of the third phalanx. It was the objective of this study to develop a method to measure the maximum strength (N/mm2) of the suspensory apparatus of the bovine distal phalanx. This apparatus includes all layers of tissue such as bone, corium, corioepidermal junction and wall horn. The feet of 13 clinically healthy beef bulls were collected from the local abattoir. Testing was performed in three locations of the wall segment (dorsal, abaxial, axial) in a material testing machine. The corium and the corioepidermal junction were set under increasing tension until failure occurred. Maximum stress was recorded. The values ranged between 2.47-3.13 N/mm2 (dorsal), 4.08-4.87 N/mm2 (abaxial) and 2.27-2.66 N/mm2 (axial). No differences could be validated statistically between front and hind claws and between lateral and medial claws respectively. Abaxial ultimate stress values were significantly higher than dorsal and axial ones. Between the two a statistical difference could not be validated. Most of the specimens (57.1%) were torn apart at the corioepidermal junction, almost a quarter of the samples (27.6%) were to a degree disrupted at the corioepidermal junction and to a certain extent in the deeper layers of the corium. A few samples showed disruption within the horn (11.5%) or at the attachment of the third phalanx (3.8%). Biomechanical features of the experimental set-up are discussed. The biological significance of these findings is that the body weight and the additional dynamic loading is predominantly taken over by the abaxial part of the claw, while the dorsal and axial aspects are less loaded.     

Evaluation of claw health in heifers in seven dairy farms using a digital claw trimming protocol and claw data analysis system

The claw health of 139 heifers with a mean age of 22.1 months (SD: 2.6) in seven free stall dairy farms in Lower Austria was evaluated. Claw lesions were assessed during functional claw trimming and documented and analysed using the digital program Claw Manager. For documentation of lesions, each claw was divided into ten zones. The prevalence of lameness, claw lesions and their severity were determined, furthermore the Cow-Claw-Scores (CCS), Farm-Claw-Scores (FCS) and Farm-Zone-Scores (FZS) were calculated.The FCS between farms was tested for significant differences. A lameness prevalence of 9.4% and an overall prevalence of claw lesions of 98.5% were recorded in these 139 heifers.The most commonly diagnosed disorders were white line lesions (WLL) with a prevalence of 87.1%, heel horn erosion (84.9%), double soles (DS; 47.5%), sole haemorrhages (SH; 33.1%) and a concave dorsal wall contour in 15.1% of the heifers. High correlation coefficients (r > or = 0.93) were found between SH and DS, WLL and DS. 86.5% of all diagnosed claw lesions were score 1 (mild), 11.1% score 2 (moderate) and 2.4% score 3 (severe) lesions. The CCS in all heifers ranged between 0 and 267, and the FCS in the seven herds was between eleven and 55. Claw zone 3 was affected most frequently and severely. Following the results of this study, systematic functional claw trimming and consequent documentation of detected claw lesions is highly recommended for heifers at the time of their first insemination to prevent claw disorders in lactating cows and to improve their well-being.     

Ultrasonographic and macroscopic comparison of the thickness of the capsule,corium, and soft tissues in bovine claws: an in vitro study

This study aimed to compare thickness of the capsule, corium, and soft tissues measured ultrasonographically and macroscopically in selected regions of bovine claws. A hundred and twenty claws (n = 120) of 15 healthy Holstein bovines were obtained. After cleaning the claws, ultrasonographic measurement of the capsule, corium, and soft tissues was performed while submerging the claws in a water bath. Macroscopic measurements were taken after cutting of the claws axially. These values were compared statistically. According to the macroscopic measurements, the mean thickness ± standard deviation (SD) of the capsule for dorsal wall and sole was 6.2 ± 0.1 and 9.5 ± 0.4 mm, respectively. The thickness of the corium and soft tissues for dorsal wall and sole was 4.5 ± 0.1 and 5.3 ± 0.1 mm, respectively. Ultrasonographically, the mean thickness ± SD of the capsule for dorsal wall and sole was 4.7 ± 0.1 and 7.8 ± 0.3 mm, respectively. The thickness of the corium and soft tissues for dorsal wall and sole was 4.3 ± 0.1 and 5.9 ± 0.2 mm, respectively. Findings demonstrated that ultrasonography can be reliably to measure of the thickness of the hoof capsule, corium, and soft tissue in bovine claw.     

The effect of claw trimming on the hoof health of Swedish dairy cattle

A 2-year experiment on the effect of claw trimming on hoof health was performed in 77 Swedish dairy herds (3444 dairy cattle) selected on herd size, breed composition and membership in the official milk-recording scheme. In the autumn, cows within each herd were blocked according to breed, parity and stage of lactation and allocated to two treatments: autumn trimming (AT) or no autumn trimming (NAT). Outcome variables were claw measurements and prevalence of hoof lesions and lameness (measured at spring trimming) and the need for hoof treatments between scheduled trimmings. At spring trimming, NAT cows had longer and shallower claws than AT cows. The average net growth of the toe wall was greater for AT than for NAT cattle, with a marked variation between housing systems. Most hoof lesions present at AT had disappeared at the subsequent spring trimming. Controlled for clustering by herd-within-year and for the effects of individual-and herd-level covariates, AT cattle at spring trimmings had significantly lower odds of lameness (OR=0.66) and of haemorrhages of the sole or white-line (OR=0.86), sole ulcer (OR=0.59) and white-line fissure or double sole (OR=0.71)-but not of moderate-to-severe heel-horn erosion or dermatitis (OR=0.96). Acute hoof treatments between claw trimmings were more common in the NAT group (OR=2.02).     

Prevalence of lameness and of associated claw disorders in Greek dairy cattle industry

The aim of this study was to assess the prevalence of lameness as well as the prevalence of claw–horn disruptions, abnormal claw shape and dermatitis in lame cows in Greek dairy farms and to evaluate their risk factors. Forty dairy farms were visited twice, during winter and during summer, and the lameness of milking cows was scored using a 5-point scale. In total 760 cows were lame (lameness score ≥ 3) and were further examined to identify macroscopically the claw disorders. The herd size, the trimming and footbathing frequency, the floor surface, the cleanness of the herd, the scraping frequency and the disinfectant used in the footbaths were recorded. The mean lameness prevalence was 18.7% and that of claw disorders observed in the lame cows was 75.4% for abnormal claw shape, 30.2% for dermatitis and 30.6% for claw–horn disruptions. Large herd size and the absence or only once per year trimming were associated with increased risk for the presence of lameness.     

Effect of different claw trimming methods on the pressure distribution under the bovine claw--an in vitro study

This survey focusses on the effects of various claw trimming methods as well as the effect of the different resulting claw shapes on the pressure distribution under the sole. 64 bovine claws were trimmed according to 3 different trimming methods, the functional claw trimming method by Toussaint Raven and two other specially modified methods.The alternative methods resulted on the one hand in long and acute-angled claws, on the other hand in a very steep claw profile. The limb samples were attached to the hydraulic plunger of a material testing machine and pressed onto a pressure distribution plate with a predefined load. The pressure distribution pattern was recorded before and after trimming. An obvious stress concentration could be observed in the bulbar region of the outer claws. All of the applied claw trimming methods induced a redistribution of load onto the inner claws while relieving the bulbar area of the outer claws.The inner claws were the main reason for the enlarged floor contact area caused by the trimming techniques.The results show that all techniques led to an improvement of stress conditions. In some cases, methods 2 and 3 were slightly superior in reducing maximum pressure and enlarging floor contact area.     

Effects of formalin footbathing on foot disease and claw quality in dairy cows

Two experiments on the effect of routine footbathing in 5 per cent formalin in preventing foot diseases and improving claw horn quality of dairy cows are described. Treatment four times a week significantly (P less than 0.05) reduced the incidence of interdigital lesions but had no significant effect on the incidence of the individual interdigital lesions or on the incidence of individual or overall diseases of the claw horn. A two year study using a divided footbath demonstrated significant improvements in some aspects of claw quality in digits footbathed in formalin. Formalin treated digits had a lower incidence and severity of erosio ungulae (P less than 0.001) a lower moisture content (P less than 0.001) and a reduced severity of haemorrhage of the sole at some sites in the claw compared with untreated digits. Formalin treatment, however, had no significant effect on the incidence of either clinical or subclinical lesions of the claw horn. The improvement in the horn quality of claws treated with formalin for six months did not increase with a further year of treatment.     

A finite element model of the bovine claw under static load for evaluation of different flooring conditions

AIM: To create a computer-based finite element (FE) model of the bovine claw and to use finite element analysis (FEA) to estimate stress and deformation of a physiologically-shaped model claw under static load, to visualise potential material weakness and to evaluate the effect of different flooring conditions. METHODS: Model geometry was derived using digitalised images from a recently trimmed, sound, hind claw from a 4-year-old Austrian Fleckvieh cow. Material properties of bovine claw horn were defined from preliminary investigations and recently established material data, using a modulus of elasticity from 200 to 600 N/mm2. Meshing of the model was performed with 42,127 elements based on 116,141 nodes. Loading of the model was defined at 756 N per claw on a hard and soft surface. RESULTS: The FE model of the bovine claw under a load of 756 N showed only minimal deformation, most of which took place at the axial wall. Highest stresses were evident in the proximal axial wall, the outer edge of the weight-bearing surface and under the heels. The claw-floor contact image showed a pressure distribution resembling the distal rim of the claw wall. On the hard surface, the maximum stresses were three times higher than those on the soft surface. CONCLUSIONS AND CLINICAL RELEVANCE: FEA allowed visualisation of the effects that loading on different floor surfaces have on the biomechanics of the claw. Uneven preparation of the claw sole resulted in high stresses at and close to irregularities of the sole. Consequences were more severe on harder flooring. The model supports the hypothesis that mechanical factors play a substantial role in the pathogenesis of claw lesions.     

Evaluation of ultrasonography for measuring solar soft tissue thickness as a predictor of sole ulcer formation in Holstein–Friesian dairy cows

The aim of this research was to investigate the correlation between the thickness of solar soft tissue (SST; i.e. the corium and subcutaneous tissue) in early lactation and sole ulcer formation in late lactation. Fifty Holstein–Friesian cows were examined three times: (1) 30 days after calving (locomotion scoring, trimming, claw examination, measurement of SST); (2) 70 days after calving (locomotion scoring); and (3) 180 days after calving (locomotion scoring, trimming, claw examination).SST thickness was measured using an 8 MHz linear probe, at two points (SST1 below the apex of the pedal bone, and SST2 below the flexor tubercle). Mean values for SST1 and SST2 were 3.26 ± 0.43 mm and 4.35 ± 0.46 mm, respectively; the two measures were positively correlated (r = 0.95, P < 0.001). At 180 days after calving, a sole ulcer was diagnosed in 12/50 cows (24%). Cows with a thinner SST had a higher risk of developing sole ulcers than those with a thicker SST. The optimal cut-off values of SST1 and SST2 in predicting cows with sole ulcers (as calculated by ROC analysis) was ?3 mm for SST1 and ?3.9 mm for SST2. The relative risk of a sole ulcer developing, based on those cut-off values was 4.25 (95 CI, 1.77–24.88) for SST1 ? 3 mm and 3.63 (95 CI, 1.18–10.8) for SST2 ? 3.9 mm.