Recognizing Ovine Footrot: Clinical Signs, Lesion Progression, and Disease Scoring

Lameness remains one of the most important health and welfare concerns in sheep production, and ovine footrot is a leading cause of painful locomotor disease in affected flocks. Caused by Dichelobacter nodosus, footrot progresses rapidly under favourable environmental conditions, particularly in warm and wet weather, with clinical signs developing within approximately 2–3 weeks following infection¹. Early recognition is critical because timely intervention not only improves animal welfare but also helps limit disease spread within the flock. 

For practicing veterinarians, understanding how lesions evolve, recognising subtle clinical changes, and applying a consistent lesion scoring system are fundamental to accurate diagnosis and effective case management. 

Recognising Early Clinical Changes 

The clinical presentation of ovine footrot varies according to disease severity. Initial lesions typically begin as inflammation of the interdigital skin, which may appear moist, reddened, and accompanied by mild hair loss. At this stage, sheep may show only mild discomfort, making careful examination essential. 

As infection progresses, inflammation becomes more extensive, and damage to the horn in the interdigital region develops. Continued progression results in detachment of the axial horn wall, followed by underrunning of the horn toward the sole. In advanced disease, separation extends to the abaxial horn wall, with severe involvement of the underlying pododermis. The most advanced stage is characterised by complete separation of the hoof capsule with extensive pododermal damage². 

The severity of clinical disease is influenced not only by the presence or absence of the protease AprV2 but also by environmental conditions and differences in host susceptibility². 

Assessing Lameness in the Field 

Lameness often provides the first indication that footrot is present within a flock. Affected sheep may stand on three legs while bearing minimal weight on the affected foot. Animals with severe disease frequently graze while resting on their carpi because of the pain associated with weight bearing². 

Observation of sheep walking in a single line, such as when entering handling facilities, barns, races, or milking parlours, provides an effective opportunity to identify affected animals. Careful assessment of gait using a locomotion scoring system improves consistency during flock examinations. Emerging technologies, including sensors, computer-assisted vision systems, infrared thermography, and reaction-force measuring platforms, may further support lameness detection where available³. 

Using Disease Scoring to Monitor Progression² 

A structured lesion scoring system allows veterinarians to assess disease severity consistently and monitor response over time. Examination of all four feet is essential, as lesions may vary between limbs. 

The Swiss scoring system adapted from Stewart and Claxton (1993) classifies lesions into six stages: 

• Score 0: Healthy, dry foot.

• Score 1: Moist, inflamed interdigital skin with mild hair loss.

• Score 2: Extensive interdigital inflammation with horn damage.

• Score 3: Detachment of the axial horn wall with underrunning toward the sole.

• Score 4: Underrunning extends to the outer horn wall with marked pododermal involvement.

• Score 5: Complete separation of the hoof capsule with extensive pododermal damage.

Consistent scoring assists in monitoring disease progression and supports communication among veterinarians and flock managers. 

Recognising Chronic Cases² 

Advanced lesions may occasionally heal slowly without treatment, but this is undesirable from an animal welfare perspective. Even after apparent healing, hoof deformities, cracks, or horn discoloration may persist. These sheep can continue to harbour infection and contribute to ongoing disease transmission within the flock. 

Carrier animals present an additional challenge because pathogens may remain hidden within horn pockets without obvious interdigital lesions. As a result, clinical examination alone may fail to identify these animals, highlighting the importance of laboratory confirmation when chronic infection is suspected. 

Practical Clinical Insights 

Early identification remains one of the most effective tools available to practicing veterinarians managing ovine footrot. Routine flock observation, systematic examination of all four feet, and consistent lesion scoring improve diagnostic confidence and facilitate timely intervention before severe hoof destruction develops. Equally important is recognising that apparently recovered or clinically normal sheep may continue to play a role in disease persistence, reinforcing the need for thorough clinical assessment alongside appropriate laboratory investigation where indicated. 

References 

1. Kuhnert P, Cippà V, Hardi-Landerer MC, Schmicke M, Ulbrich S, Locher I, Steiner A, Jores J. Early infection dynamics of Dichelobacter nodosus during an ovine experimental footrot in contact infection. Schweiz Arch Tierheilkd. 2019 Jul 1;161(7):465-72. https://sat.gstsvs.ch/fileadmin/datapool_upload/IgJournal/Artikel/pdf/SAT_07_08_2019_Kuhnert.pdf 

2. Zanolari P, Dürr S, Jores J, Steiner A, Kuhnert P. Ovine footrot: A review of current knowledge. The Veterinary Journal. 2021 May 1;271:105647. https://www.sciencedirect.com/science/article/pii/S1090023321000423 

3. I. Gelasakis A, I. Kalogianni A, Bossis I. Aetiology, risk factors, diagnosis and control of foot-related lameness in dairy sheep. Animals. 2019 Jul 31;9(8):509. https://www.mdpi.com/2076-2615/9/8/509