Sheep farming

What causes Lameness in Sheep?

A report by the UK Farm Animal Welfare Council (FAWC) published in 2011 included the startling estimate that at any given time, one in every ten sheep is lame.  This is why many regard lameness as the sheep industry’s biggest welfare issue.  Over the next two blog posts we will consider the most important causes of lameness and explain how some shepherds have drastically reduced the level of lameness in their flocks.  

Causes of Lameness

A number of different conditions of the feet and legs can lead to lameness in sheep.  However, two thirds of lameness can be attributed to either scald (also known as interdigital dermatitis) or footrot, both of which are caused by the same bacterium Dichelobacter nodosus.

Graph

Sheep BRP Manual 7 (AHDB 2016)

Dichelobacter nodosus organisms live on the skin between the claws of the foot.  Away from the sheep D. nodosus is extremely fragile, surviving for a maximum of 10 days on the ground.  The organism spreads easily between sheep, particularly when conditions are wet and muddy.    

In cases of Scald the skin between the claws of the foot is affected, becoming inflamed and acutely painful (see diagram).  A grey discharge forms on the affected skin surface and hair in this area may be lost.  Scald can frequently appear as an outbreak, particularly in lambs. 

Foot-Diagram1

Sheep BRP Manual 7 (AHDB 2016)

In Footrot the D. nodosus infection extends from the interdigital skin to affect the rest of the foot.  Typically this starts at the heel, where the hoof horn begins to separate from the underlying soft tissues.  If left untreated this underrunning will extend across the sole of the claw, and then progress upwards beneath the harder horn of the hoof walls.  A distinctive sign of footrot is a characteristic foul smell. 

Foot-Diagram2
Sheep BRP Manual 7 (AHDB 2016)

'Self Cure’ is rarely the answer

Sheep with footrot infection rarely “self-cure”If left untreated most affected feet will become chronically diseased, leading to prolonged lameness and deformity of the horn.

Whether a case of interdigital dermatitis develops into footrot will depend on a number of different factors – the strain of D. nodosus present and underfoot conditions being the most important.  Early treatment of scald also reduces the chance that footrot will develop.

In part two of this blog we will look at the costs of lameness and how we can apply our knowledge to reduce its impact on the flock.

 

For further information, please see the product SPC, or contact your veterinary surgeon, SQP or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. www.zoetis.co.uk . Always seek the advice of your medicines provider. Use medicines responsibly (www.noah.co.uk/responsible) 

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