Digital dermatitis (DD), also known as Mortellaro's disease or heel warts, is arguably the most significant infectious cause of cattle lameness worldwide. Its prevalence, pain burden, and economic impact make it a priority welfare and production challenge requiring systematic herd-level management.
Digital dermatitis is a polymicrobial infectious disease of the skin of the feet, particularly affecting the area between the heel bulbs and at the skin-horn junction. Treponema species are the primary causative organisms, though other anaerobes including Fusobacterium and Dichelobacter are present. The lesion progresses through defined stages: M0 (healthy), M1 (early active—small red ulcer), M2 (acute active—large, painful ulcer), M3 (healing), M4 (chronic—proliferative tissue), M4.1 (active on chronic background). Staging is important for treatment and monitoring.
Active DD lesions (M2 stage) are acutely painful, causing significant lameness and behaviour changes consistent with pain: reduced weight-bearing, altered gait, reluctance to walk, reduced time at the feed barrier, decreased lying time, and reduced feed intake. Chronic lesions may be less acutely painful but predispose to recurrence and progressive structural changes. The welfare burden of DD in high-prevalence herds is substantial.
DD is highly contagious, spreading through direct contact between feet and through contaminated slurry. High-risk factors include: wet conditions (slurry accumulation in alleys), high stocking density, poor slurry removal frequency, shared foot-bathing infrastructure, introduction of infected animals without quarantine, and poor claw health generally. Indoor housed cattle are at higher risk than extensive pasture-based systems.
Individual treatment of active lesions with topical antibiotics (oxytetracycline spray) or salicylic acid is effective for M2 lesions. Bandaging for 2-3 days improves healing rates. Systemic antibiotics are rarely justified for DD. Chronic M4 lesions may require more aggressive treatment including debridement. Pain relief (NSAIDs) should be provided for acutely lame cattle—this is both a welfare requirement and improves treatment outcomes.
Regular foot bathing is the cornerstone of herd-level DD control. Copper sulphate (3-5%) and formalin are traditional treatments; antibiotics in footbaths are now restricted in many countries due to antimicrobial resistance concerns. Effective foot bathing requires: sufficient depth (15-20cm), appropriate bath length (>3m), correct concentration, regular replenishment, and placement at natural traffic points. Dry foot bathing (superabsorbent powder) is an alternative approach gaining traction.
Effective DD control requires a systematic approach: regular foot scoring to assess prevalence and target intervention, prompt treatment of active lesions, regular foot bathing of the whole herd, environmental management to reduce slurry accumulation, biosecurity for new arrivals, and routine trimming. Tracking M-stage prevalence over time allows objective assessment of control programme effectiveness and guides resource allocation.