Advice on best practice for treating and controlling foot rot

Advice on best practice for treating and controlling foot rot.

Background

This advice is the result of a discussion by presenters and members of SVS during a session on current knowledge, based on the most recent results of research carried out at Warwick and Bristol Universities.

Key points

• Key role of D nodosus, now known to cause interdigital dermatitis (ID)
• Genetic variations in D nodosus which lead to variations in severity (and benign strains can cause FR in the right environmental conditions)
• Genetic variations in susceptibility of the sheep host
• Weight of infection is important in spread
• Wet underfoot conditions allow spread

DIAGNOSIS – make sure this is accurate

INSPECT daily if possible, certainly at not more than 3 day intervals, to reduce spread

TREAT every individual lame sheep as soon as seen, when lameness is mild – don’t wait until it has become severe

Adults

• 1ml/10kg bodyweight of oxytetracycline LA (no more than 5ml at one site)
• Clean interdigital space
• Spray i/d space and foot with antibiotic spray

Lambs

• Inject if clinical FR present
• For ID only, spray with antibiotic

Chronic cases

• Cull, or give intensive treatment (9 days parenteral antibiotic treatment)

FOOT TRIMMING – do NOT carry out, as this delays healing

SEPARATE infected animals until cured

CULL repeat offenders

SELECT animals with sound well-shaped feet

BUY only sound replacements which have never been lame

IDENTIFY key control times to prevent spread – eg housing and turn-out after lambing

ISOLATE new stock

VACCINATE –generally agreed to be helpful

CLEAN GRAZING – allow 2 weeks break (as long as possible if aiming for eradication)

FOOT BATHING – facilities must be good and product used at correct concentration

• not necessary for treatment (but if used and working well, carry on) – use injectable antibiotics as above instead)
• useful for outbreaks of ID in lambs
• useful before housing to ensure feet are healthy at this time, as infection will spread in housed animals
• useful at gathering for other reasons (potential to spread bacteria)

A note on the use of whole-flock treatment with antibiotics

Tilcomycin and gamithromycin (not licensed) have been used in flocks with either FR or CODD or both.

The consensus was that this should only be used in an eradication programme, not repeated on an annual basis. This is because of the widespread exposure of both the target bacteria and other bacteria (especially potentially zoonotic enteric bacteria) to macrolides, increasing the risk of resistance developing.