Digital dermatitis can be brought under control through a one-hit treatment approach. Farmers Guardian reports.
The ‘blitz treatment’ of every cow in a herd infected with digital dermatitis will control the disease far more effectively than treating on an ‘as and when’ basis, according to Sara Pedersen from the veterinary consultancy, Farm Dynamics.
Speaking at the Cattle Lameness Conference held near Worcester, Ms Pedersen said: “The idea behind treating everything at the same time is that once the digital dermatitis lesions start to heal, we are no longer feeding the environment with infection.
"This reduces the risk of the disease being picked up and passed on to other cattle, helping to break the cycle.”
This approach can break the digital dermatitis cycle and lead to a dramatic reduction of infection to very low levels across a herd.
The most effective measures of treatment are not well known and the tendency to footbath in the face of an outbreak will not address the problem. Furthermore, treatment only needs to be simple using a product already available in most medicine cabinets on the farm.
The rationale behind her advice come from the fact that the primary pathogens responsible for digital dermatitis, treponeme bacteria, only survive in slurry for up to 24 hours.
Ms Pedersen’s recommendation for identifying and treating the disease is also simple, involving a whole herd inspection of every cow in the parlour, using a hose to wash rear feet, particularly between the heels, and, where necessary, a mirror or torch to pick up sites of infection.
This procedure overcomes the problem of using lameness itself as part of the diagnosis since treponemes may only cause lameness some months after the initial infection.
She said: “By the time you see a lame cow, it’s likely to have had digital dermatitis for a couple of months, so it has had that time to spread.”
Once infected animals have been identified, treatment should be
immediate and simultaneously
address every single case.
Ms Pedersen said: “Treatment should preferably be in a crush, as success rates are slightly higher than treating when the cow is standing. In addition, Red Tractor Assurance standards don’t allow the use of antibiotic sprays during milking.”
Treatment should take the form of a topical antibiotic such as oxytetracycline spray applied to the lesion, a use for which it is licensed.
Ms Pedersen said: “Unless treated cows can be separated from the
unaffected cows, footbathing should not be carried out during the treatment phase.
“A lot of people don’t think the topical antibiotic works, but that’s often because the foot has not been prepared correctly or sufficient repeated treatments aren’t given.”
Recommending spraying for three consecutive days, or until the lesion has started to heal, the next stage of the process is the use of a footbath.
“Only start footbathing when all treated lesions are covered by a thick black scab and no longer painful,” she added. “There is no blueprint footbathing protocol, but it is important to use a product, that is effective and to re-assess your footbath design to ensure it is disinfecting the foot sufficiently – aiming for at least two and preferably three dunks of each hind foot.
“Bathing prevents dormant lesions recurring and new ones starting, but research tells us we should no longer be viewing footbaths as treatments. There is no longer justification for the use of antibiotic footbaths as they should have a seven-day milk withdrawal, present a massive risk of environmental residue and involve treating the whole herd, rather than just the affected cows.
“A lot of farmers think they can footbath their way out of a flare-up and typically increase the frequency of bathing or the strength of solution, but that’s not getting to the bottom of the problem.
“Just as with mastitis, you would not teat dip your way out of an outbreak, but treat individual cases. I don’t think you can ever eliminate the problem but if you can stop new cases and stop dormant lesions recurring, then over time you can control the disease and keep it at very low levels.”
A trial at Marcross Farm, near Llantwit Major in south Wales, has reinforced Sara Pedersen’s advice. Its owner, Hopkin Evans, has battled a long-term digital dermatitis problem, treating infection whenever it was identified over many years.
At the start of trial, 37 of the 144 adult cows had an active or recurring lesion on one or both of their hind feet. There were 49 active/recurring lesions, equivalent to 14 per cent (1 in 6) hind feet affected. The farm turned to the ‘blitz’ treatment protocol followed by a more effective footbathing regime including daily footbathing in 5 per cent formalin and the installation of a new 4m-long footbath.
At a follow-up review six weeks later, the number of active/recurring lesions in the herd had declined to three. At another review five months from the start, there was just one case present, and the farm now continues to average only one case per month.
Inspect: Identify all cows with digital dermititis
Blitz treat: Simultaneously treat everything with an active/recurring lesion with a licensed topical antibiotic until a thick black scab forms
Prevent: Re-start footbathing – consider product selection, footbath design and frequency
Monitor: Re-inspect feet every month or six weeks