Contagious Footrot

Also known as:

Scald

Description

An economically important disease causing lameness in sheep, is associated with under-running of the hoof and a characteristic 'odour'. Footrot is caused by Dichelobacter nodosus together with Fusobacterium necrophorum. Moisture and trauma allow F. necrophorum to enter which aids bacterial penetration of the epidermis by D. nodosus resulting in necrosis and [Inflammation - Introduction|[inflammation]]. Carrier animals are a major source of infection and are difficult to find as they are often sub clinical cases.

Signalment

Affects sheep, particularly those kept in wet warm conditions.

Diagnosis

Can be made on a history of lameness and rapid spread amongst the flock in combination with clinical signs.

Clinical Signs

Lameness is often the first clinical sign to be noted and can vary in severity. Under-running of the horn is present and there is often a necrotic discharge which causes the characteristic foul 'odour'.

Pathology

Grossly: Early lesions are red, moist, swollen and interdigital skin is eroded. This spreads to epidermal matrix of the hoof leading to separation of the horn and malodorous exudate. Regeneration is attempted as germinal epithelium is not destroyed. Chronic infections can result in a long misshapen hoof. Benign footrot (scald) results in only the interdigital skin being affected and a slight separation of heel horn. Mostly this is the type occuring in cattle.

Treatment

A single dose of antibiotics ideally penicillin or oxytetracycline gives rapid resolution.

Foot-bathing is also useful zinc sulphate and formalin can be used. There should be a dry area wher the shhep can stand post dip to give the chemical time totake affect. This is more useful as a form of control preventing footrot.

vaccination is a further form of control. This only gives 12 weeks of protection and hence must be

Culling of repeatedly affected animals and hence carriers of disease.