Sole ulcer

What it is

Sole ulcer is a claw horn disruption lesion: the corium (dermis) of the sole is repeatedly compressed between the third phalanx and the ground, bleeds and stops producing healthy horn. A sole haemorrhage appears first; if the insult continues, the horn is lost and the corium is exposed, where it may granulate or become infected. The typical lesion lies at the sole-heel junction, beneath the flexor tuberosity of the distal phalanx. Variants occur at the tip of the claw (toe ulcer) and in the heel.

Around calving the suspensory apparatus of the distal phalanx becomes laxer and the phalanx can sink or rotate inside the horn capsule. Compression increases with time spent standing on hard floors, uncomfortable beds, poor trimming and overloading of the lateral claw of the pelvic limb. The role of ruminal acidosis (the classic "subclinical laminitis") is debated.

White line disease shares these factors: the junction between wall and sole separates, dirt enters and an abscess forms, mostly in the abaxial heel region of the lateral claw of the pelvic limb. Pus can undermine the sole or track up the wall and break out at the coronary band.

Who it affects

Mainly high-yielding dairy cows in free-stall housing with concrete floors, more often multiparous cows and from mid-lactation onwards. It is much rarer in heifers and in pasture-based systems or on deep bedding.

Anatomy involved

• Claws (ungulae): the ulcer lies in the sole, in the axial region of the sole-heel junction, mostly of the lateral claw of the pelvic limb; in the thoracic limb the medial claw is more often affected. White line disease affects the white line, the junction between wall and sole. Beneath the horn lie the corium and the digital cushion, a fatty and fibrous tissue that absorbs pressure.
• Phalanges of the pelvic and thoracic limbs: the distal phalanx (third phalanx) rests on the corium of the sole; its flexor tuberosity, where the deep digital flexor tendon inserts, lies just above the typical ulcer site. If infection progresses deeply it can cause osteitis of the distal phalanx, septic arthritis of the distal interphalangeal joint, bursitis of the navicular (distal sesamoid) bone or tenosynovitis of the deep digital flexor.

Clinical signs

Lameness of gradual onset, often in one pelvic limb, with the cow unloading the heel and the lateral claw; she may stand with the limbs abducted or bear weight on the medial claw. Paring the sole reveals yellowish or reddish horn with haemorrhage, a defect with exposed corium, or protruding granulation tissue. Pressure with hoof testers is painful. In white line disease there is a fissure or dark spot in the white line with black, foul-smelling pus under pressure. When deep complications are present, swelling appears above the coronary band and lameness is severe.

Diagnosis

• Inspection of the lifted foot and functional trimming: the lesion is seen when sole horn is removed; hoof testers help locate the pain.
• Locomotion scoring of the herd to detect lame cows early.
• Radiography or ultrasonography when involvement of the distal phalanx, the distal interphalangeal joint or the tendon sheaths is suspected.
• Differential diagnosis: sole abscess, foreign body, fracture of the distal phalanx and infectious diseases of the skin of the foot.

Treatment and prevention

• Therapeutic trimming: remove loose horn and unload the injured area by lowering the affected claw.
• Block glued to the sound claw to raise the affected one and relieve weight bearing.
• Non-steroidal anti-inflammatory drugs to control pain and inflammation.
• For deep complications: surgical debridement, digit amputation or arthrodesis of the distal interphalangeal joint.
• Prevention: regular functional trimming, early detection by locomotion scoring and prompt treatment, cow comfort (soft beds, enough lying time, less standing time in the holding pen), floors that are neither abrasive nor slippery, and body condition management around calving.
• Drug use in food-producing animals is subject to national regulations and to withdrawal periods for milk and meat.

Key studies

• Solano et al. (2016), cross-sectional study of 28,607 cows on 156 farms in Alberta (Canada), with lesions recorded by hoof trimmers. On farms where the whole herd was trimmed, sole ulcer was found in 6% of cows and white line disease in 4%, in 92% and 93% of herds. Cows in parity 4 had 5 and 7 times higher odds of these lesions than first-parity cows, and housing in free stalls at least doubled the odds compared with deep-bedded packs. It is observational and trimmers differed in their recording.
• Bicalho et al. (2009), cross-sectional study of 501 Holstein cows. Sole ulcer prevalence was 4.2% in first-parity and 27.8% in older cows, and white line disease prevalence 1.0% and 6.5%. Both were associated with a thinner digital cushion, measured by ultrasonography: cows in the thickest quartile had a lameness prevalence 15 percentage points lower than those in the thinnest. Cushion thickness was associated with body condition and fell from calving to a nadir at 120 days. A cross-sectional design cannot prove causation.
• Newsome et al. (2017), prospective cohort of 179 cows (158 completed the study) followed from before calving. Thin sole soft tissue and thin or decreasing back fat increased the likelihood of lesions, but thinning of the soft tissue between assessments did not predict new lesions. This challenges the widespread idea that loss of body fat thins the digital cushion and causes the lesions.
• Thomas et al. (2015), randomised controlled trial on 5 farms in newly lame cows with claw horn lesions, all given a therapeutic trim. At 35 days, 11 of 45 (24.4%) were sound with trimming alone, 14 of 39 (35.9%) with a block, 12 of 42 (28.6%) with ketoprofen and 23 of 41 (56.1%) with a block and ketoprofen; only this last combination was better than trimming alone. The cows were newly and mildly lame.
• Wilson et al. (2022), 34-month randomised controlled trial with 132 heifers per group in a single herd (438 analysed). Those given ketoprofen for 3 days after each calving, plus trimming, a block and ketoprofen whenever lame, were less likely to become lame (OR 0.66) and severely lame (OR 0.28) than those treated with trimming and a block alone. A single herd limits generalisation.
• Sadiq et al. (2024), systematic review of 10 studies on the treatment of claw horn lesions. Trimming with a block, with or without an anti-inflammatory, was associated with more complete and faster resolution than trimming alone, but the effect on locomotion and pain was unclear and the studies were highly heterogeneous.