Lameness cuts productivity and increases costs in sheep flocks, but early treatment can significantly reduce the impact, writes Laura Green, Jasmeet Kaler, University of Warwick, and Rose Grogono Thomas, University of Bristol.
Over the past 10 years we have been investigating lameness in sheep and, in particular, footrot and scald, and have made some interesting findings:
• When you leave a lame ewe untreated for more than four days her body condition starts to fall and she will feed her lambs less well.
• More than 80% of lameness is caused by scald and footrot. These two diseases are caused by the same bacteria; footrot is a more severe presentation.
• The best way to treat scald and footrot in ewes is to catch individual ewes as soon as they are lame (whatever time of year), diagnose the cause of lameness and treat sheep with footrot or scald with a high dose (1 ml/10kg) of long-acting oxytetracycline and spray the foot with a disinfectant or antibiotic.
• More than 90% of ewes with footrot will recover within 10 days when treated like this (and 70% within five days). Sheep with scald recover in 1-2 days.
• Trimming hooves of sheep with footrot or scald will delay their recovery. Only 50% will recover within 10 days when you trim their feet, even with antibiotic injections, and less than 30% without antibiotic injections.
• Delaying treatment of footrot will cause the foot to become misshapen. These sheep are more likely to become lame again and might harbour the bacteria and spread disease to other members of the flock.
In a recent study we compared two groups of sheep: Treatment and control. Our treatment group of 350 ewes were turned within three days of becoming lame and those with footrot or scald were injected as above. We did not trim the feet of lame sheep. Our control group of 350 ewes were managed in a way that is fairly typical, within 1-2 weeks of becoming lame those with footrot or scald were foot-trimmed and foot-sprayed with terramycin. Within eight weeks the level of lameness in the treatment group was less than 2% while in the control group it was 8%. Ewes in the treatment group had higher body condition at weaning, were less likely to be barren and had more lambs that grew faster the next season. Treatment lambs were, on average, finished six weeks faster than lambs in the control group. We estimated that the 350 treatment ewes earned about £6 extra - even once we had accounted for treatment costs.
This might seem a lot of work. If you have a lot of lame sheep it will be at first.
So, to avoid having to treat a lot of lame sheep –
1. Catch a sheep as soon as it is lame.
• When it has footrot or scald and you catch it within three days and treat as above you will stop it infecting other sheep and you will have fewer sheep to treat.
• You will also give it the best chance of a full recovery so its feet stay in good conformation and it will be less likely to get lame again.
2. Cull repeatedly lame sheep
• Mark sheep you treat with a long lasting dot (or use a recording system) at the top of the leg that you treat.
• If a sheep has footrot more than once, cull it - most of your lameness will come from a few sheep. Culling will prevent the spread of infection from these sheep and will stop you wasting time and money treating the same sheep repeatedly.
3. Separate out lame sheep on every possible occasion. Isolate lame sheep whenever you can, it can be difficult, but at strategic times it is possible to separate lame sheep. Lame sheep can then be treated and those that do not respond can be culled.
• Do not turn out lame sheep with sound sheep.
• House lame sheep separately from sound sheep.
4. Check the feet of sheep that you buy in and check whether the flock has CODD.
Should we be trimming feet?
• Routine foot trimming does not control footrot, it is not an alternative to daily care of lame sheep.
• Trimming the feet of lame sheep delays recovery from footrot.
• In all our studies routine foot trimming is linked to higher levels of lameness - we do not know why. About 20% of farmers do not trim their ewes' feet routinely. They tell us the toes are long when it is wet and short when it is dry. Those that have stopped say that either there is no difference in levels of lameness or that levels have gone down.
• It takes about 40 hours to trim 500 sheep's feet. It might be better to use this time inspecting all the feet and separating and treating sheep with scald and footrot before turn out and housing. Some farmers and vets are adamant feet should be returned to a good shape each year and it might be that on certain farms trimming is needed - but think about whether that includes your farm. Some conditions such as shelly hoof currently require foot trimming.
A good shape includes:
• Leaving a ridge of wall horn proud of the sole so the sheep is weight bearing on the wall.
• Never trimming to blood as infection and toe granulomas can occur.
Footbaths are not as effective in treating footrot because the disinfectant cannot get deep into the foot to kill the bacteria. Clean, well prepared footbaths can be useful to disinfect feet before housing and to treat scald outbreaks in lambs, although keeping footrot low in ewes can prevent outbreaks of scald in lambs.
Some farmers have found vaccination useful in addition to the treatment above, particularly when a flock has high levels of lameness (15% or so). Vaccination can dampen the severity of disease.