Farm Ireland
Independent.ie

Wednesday 22 November 2017

Take steps to eradicate all forms of lameness

Peadar O Scannail

My, how the winter has hit us! Gone are mild autumn evenings with our sheep grazing the extended dry days of the season. Sheep disease in all its forms is to be pinched out of the flock at this time.

Lameness is a problem on a lot of farms we visited recently. In some flocks we saw sporadic cases, with the majority of ewes showing no problems at all. In others we found more than 20pc of the sheep with foot problems and, on one farm, we had more than 60pc of adult ewes affected -- and more than half of them showed lameness on more than one foot.

A correct diagnosis is vital to ensure a speedy return to full fitness. There are three main causes of sheep lameness:

1. Foot scald;

2. Footrot;

3. White line disease (shelly hoof).

1. Foot scald involves abrasions and cuts between the toes of the sheep's foot. The area is inflamed and sore but usually dry to look at and feel. It is quite painful but is usually limited to the soft skin between the toes and at the base of the foot. The cause is usually environmental in origin, such as the nature of grass cover that sheep are walking through. Long stemmy old-lay is abrasive, as are scutch and briars, or even stubble in the autumn. Grazing the 'long-acre' of harvested fields can be included in the history of lowland flocks. Extra-thick gorse and rough grazing of hill flocks sees more sheep scald.

Foot scald is sporadic in nature and should not cause lameness outbreaks.

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2. Footrot is more likely when greater numbers of the flock are affected. Typically, 30-60pc of adult sheep would be showing lameness. Examination of the foot reveals a messy, smelly lesion between the toes, with a number of feet showing a split between hair and hoof. Where hoof separation occurs, we usually diagnose footrot, and treat with zinc sulphate, and antibiotic footbaths are also often required. Correct diagnosis is paramount with early detection helpful to stem the issue.

This is a contagious disease and separating the affected sheep from the remainder may be prudent in the early days of an outbreak. Drying off the leaky pipes near water and feed areas is a help. The use of hydrated lime can form part of the flock health plan. Vaccination will be discussed on another day.

3. White line disease (shelly hoof) is a rare form of foot disease in Irish flocks. The brittle hoof shows cracks and weaknesses along the wall and sole, where the white line junction exists. It is often diagnosed as footrot, but incorrectly so as we never see hoof separation with true white line disease.

Messy

It differs from footrot in that we don't see the messy, wet lesions between the toes as we do in footrot. The outer wall of the hoof is often brittle or broken, and badly undermined, hence the name shelly hoof. Hoof paring and the use of formalin footbaths helps to treat and prevent this lameness. Please note: formalin baths must be mixed to a 3pc solution at a maximum. Excessively strong formalin footbaths are damaging to the skin between the toes and at the hoof line.

As I said earlier, it is a rarer form of lameness, but in fact a not-too-sore version of the disease was found in more than 80pc of hill flocks in one particular study. Up to 50pc incidence in lowland flocks was found in the same study. This incidence we pass off as a 'normal' finding at hoof clipping sessions. We pare, we trim and we use a footbath, and away goes a sound animal.

Good hoof trimming and regular use of footbaths (non-antibiotic) is best husbandry practice on all sheep farms. Zinc sulphate, copper sulphate and formalin are best bath solutions. Antibiotics should be avoided as much as possible and should be kept for those cases that truly need them.

One final note: Mix the baths to correct concentration only. Adding a 'tilly', as they used to say, may burn the sheep's feet and cause more problems.

Peadar Ó Scanaill is a member of the Veterinary Ireland animal health committee and is a practising vet in Ashbourne, Co Meath

Irish Independent