Understanding Mortellaro disease (digital dermatitis) — the most significant cause of infectious lameness in dairy cattle.
Digital dermatitis causes significant welfare impairment as one of the leading causes of dairy cow lameness. The lesions — initially small but rapidly developing into painful, ulcerated, strawberry-like papillomatous growths — cause intense localised pain. Affected cows are acutely lame, reluctant to bear weight on the affected foot, and show reduced mobility that impairs feeding, social interaction, and reproductive behaviour.
The chronic M4 stage of digital dermatitis — a scarred, black proliferative lesion — appears healed but harbours spirochaetes that reactivate to cause acute M2 disease when conditions are appropriate. Cows in the chronic stage appear sound but carry significant disease burden and serve as reservoirs for herd spread.
Control requires a comprehensive approach: regular footbathing with effective bactericidal agents, prompt individual treatment of active lesions (topical oxytetracycline or lincomycin sprays under bandage), regular locomotion scoring to identify affected animals early, and biosecurity to prevent introduction of new spirochaete strains.