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Sheep lameness

Course: Diseases and pests in sheep | Last Updates: 12th October 2015

 
Ruth Clements
Head of veterinary services
FAI Farms
Biography >>
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Sheep lameness not only represents a significant animal welfare issue, but a substantial drain on farm profitability, with lameness estimated to cost the UK sheep industry £24m a year.

For too long sheep lameness has been widely seen as an inevitable part of sheep production.

However, the start of 2014 heralded a significant development in the fight to control the issue with the Sheep Lameness Stakeholder Group agreeing to make FAI Farm’s five-point plan (see below) for controlling lameness an agreed national strategy.

As a result, the industry now has a practical control framework to help stamp out lameness and meet government targets to reduce lameness prevalence as set out by the 2011 Opinion on Lameness in Sheep report by the Farm Animal Welfare Committee. In it, the report recommended the industry reduce lameness prevalence to 5% or less by March 2016 and to 2% or less by March 2021.

Although exact national lameness figures are not known, farm experience shows lameness is a significant issue on many farms, with some struggling with levels of more than 10%.

Foot-rot and scald are the primary infectious causes of sheep lameness. Both are caused by the same infectious bacteria, with scald being a precursor to foot-rot. It is also likely contagious ovine digital dermatitis (Codd) is prevalent on some farms, and is often misdiagnosed as foot-rot.

Diagnosis

Correct diagnosis is crucial as treatment protocols will vary depending on what issues you have. Work with your vet to diagnose the issues on your farm. Sometimes a farm can have foot-rot and Codd at the same time, which increases control challenge.

Although the five-point plan is designed for foot-rot and scald, Codd is also a contagious bacterial disease, which means the plan is likely to help control it as well.

Scald and foot-rot

  • Both scald and foot-rot are caused by Dichelobacter nodosus bacteria.
  • Scald is a precursor to foot-rot.
  • Scald symptoms include reddening and moistness in the interdigital space with a white, pasty scum on top and strong smell. This can progress into foot-rot, with separation of hoof horn starting in the interdigital space and a grey, foul-smelling pus.

Once established, the sole horn and outer wall horn may be underrun.

Codd

  • Thought to be caused by treponemes (bacteria).
  • Infection starts as a red, raw lesion at the coronary band. The infection progresses to underrun the hoof horn capsule downwards towards the toe. The whole horn capsule may fall off.

Spread

All of these infectious lameness diseases are spread in a similar way.

Think of a lame ewe with orange paint (representing bacteria) on her infected foot. As she walks around the farm, she is leaving splodges of paint (bacteria) that other animals can walk through and pick up infection. The more lame ewes, the greater the chance animals will walk through the orange paint.

There will also be increased risk of disease spread where stocking rates are high – for example, around water troughs.

The five-point plan has been designed to control infectious disease by helping to reduce this disease challenge, while at the same time building resilience and establishing immunity in the flock.

The plan includes:

  • Culling badly or repeatedly infected animals
  • Quarantining incoming animals
  • Prompt treatment of clinical case
  • Avoiding spread at handling and gathering
  • Vaccination

Sheep farmers committed to using all parts of the five-point plan quickly witness significant drops in lameness. For example, farms with 10% lameness have reported levels of under 2% after the first year. Farms that get foot-rot under control in their ewes are also likely to see less scald in lambs due to reduced disease challenge.

Although the national 2016 target is less than 5% lameness, individual farms should be striving for less that 2%. At that level, you can be confident lameness is under control.

The main hurdle to get over is to stop thinking lameness is an inevitability. Commonly, farmers use bad weather as a reason for higher levels of lameness, but it does not have to be the case.

By adhering to each part of the five-point plan, the aim is to build up a “safety buffer”. That means in times of stress, the flock is less likely to succumb to disease as they have built resilience and immunity, while disease challenge has been reduced.

How to start tacking lameness

The first thing to do when starting to control lameness is to look at the five-point plan and identify where the gaps are on your farm. Work out how you are going to implement the points in the short, medium and long term.

Most farmers will already be doing some parts of the plan, but the critical success factor comes when you take action in each of the five points. Cutting corners will mean it will be much harder to get lameness under control.

Culling

This is about building natural resilience to lameness by culling individuals that are prone to infection. Farmers often struggle with the concept of culling “productive” ewes, but it is important to realise these chronic lame animals are spreading disease to others and causing bigger problems.

Adopt a two or three strikes and you’re out rule. Weaning is a good time to cull individuals that have been treated for lameness twice or more or have mis-shapen, chronic feet. Be prepared to cull heavily in the first year at maybe 4% more than usual, but this will drop dramatically in the second year.

Make sure you record so you can track treatments. Use a spray marker to identify individuals you have treated and identify those for culling with a tag or through EID.

Quarantine

Quarantine is essential to prevent the introduction of different strains of infectious lameness. This is particularly relevant to Codd, as introducing it to a naive farm can quickly cause a big outbreak.

Ask the farm where you are buying from if they are using the five-point plan. Do not buy lame animals and work with your vet to design a robust quarantine strategy.

In general, bought-in animals should be quarantined for four weeks. It is also worth tipping up animals and examining feet as the early signs of Codd may not result in visible lameness.

Prompt treatment

Prompt treatment is needed to prevent problems from escalating. Getting on top of scald quickly is particularly important to prevent it developing into foot-rot. In cases of scald, spray the foot with an oxytetracycline spray immediately.

Foot-bathing can be a useful strategy at the early signs of scald. In general, foot-bathing is good at dampening down infection, but it is not the most affective treatment.

If you are foot-bathing, ensure you do it well as you could do more harm than good by spreading infection during handling. Stock must be able to stand in the foot-bath for sufficient time and then stand on a clean, dry area for feet to dry.

Do it at the same time as another handling event as moving stock specifically to foot-bath could increase disease spread.

Foot-rot and Codd will both need antibiotic treatment – consult your vet for up-to-date treatment advice.

It is also important to avoid foot-trimming lame sheep as this has been shown to delay healing and could also spread infection via the hoof knife.

Avoid

Put measures in place to avoid spread of infection round the farm. Liming around areas of high stock traffic such as gateways, handling areas or water troughs can help.

Try and handle stock on dry, hard standing or when using mobile handling equipment, rotate around different areas of ground. Reducing the number of handling events by combining two jobs at a time can also reduce risk. Also think about creating an isolation pen for lame animals at housing.

Vaccination

To build immunity, vaccinate all breeding stock for foot-rot, including rams. Vaccination is commonly given around times of highest risk such as housing, when stocking rates are high. Talk to your vet about farm-specific challenges and how often and when your flock should be vaccinated.

Golden rules:

  • Stop thinking lameness is inevitable
  • Use all parts of the five-point plan – if you pick and choose you will not successfully get on top of lameness
  • Work with your vet to identify lameness problems on your farm and how you can implement the five-point plan
  • Do not foot-trim lame animals
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