Facial eczema in sheep
Sheep are very susceptible to facial eczema (FE). The resulting liver damage can severely affect their welfare, affect production and fertility or cause death. Prevention is imperative.
The facial eczema risk season generally runs from late December until May. Ideal conditions for fungal growth are warmth and humidity, especially when nighttime temperatures exceed 12oC, grass minimum temperature is above 14oC and rainfall is regular. Spore numbers can increase extremely rapidly under the right conditions.
Having your own spore counts done regularly can be very useful. A spore count of >80,000 spores/gram is dangerous to grazing animals. Once spore counts reach 30,000, preventative action should be taken. Remember that long-term exposure to lower levels of spores can also be very damaging.
Sheep suffering from acute facial eczema will show some or all of the following signs:
Rubbing and scratching
Swelling and reddening of the ears. The ears may become heavy and ‘drooped'
Swelling under the jaw and around the eyes and nose
Crouching as if to urinate
Animals showing the above signs of facial eczema are just the tip of the iceberg, there will be many more in the flock with liver damage that will continue to effect their growth, fertility and production. There is no treatment for facial eczema, so prevention is imperative!
Zinc protects the liver against the oxidative damage caused by sporidesmin (the FE fungal toxin). Zinc treatment needs to begin before high risk periods to be effective. Ideally dosing should begin at least 2 weeks prior to the danger period.
Water treatment with zinc sulphate is not an option for sheep as it is for cattle because sheep drink less water. The concentration of zinc required to achieve adequate intakes means that the water tastes bad and they drink even less!
The most practical way of supplementing sheep with zinc is to give Time capsules® These are zinc boluses given orally that sit in the rumen and slowly release zinc over a period of 6 weeks. A second bolus may be required depending on the length of the facial eczema season that year.
Zinc can also be administered as a zinc oxide slurry drenched weekly. This is effective but not practical for large numbers of sheep. It may be an option for lifestyle blocks.
Another method of reducing animal intake of spores is to spray the pasture with a fungicide. This kills the facial eczema fungus, hence reducing spore counts. The best time to spray is before spore counts begin to rise.
Grazing management should be part of every farm's facial eczema prevention plan. Higher risk paddocks include those that are sheltered, north-facing; rye-grass dominated and have a large amount of dead litter at the base. Avoid grazing these paddocks during high risk periods and try not to let pasture become too rank during the late spring, summer period.
Do spore counts on paddocks before grazing to assess their risk. Avoid grazing to very low levels as most spores are concentrated towards the base. Safe feeds eg hay, silage and crops can also be used during risk periods to prevent spore intake.
It is important to be aware of the current facial eczema risk situation so that preventative measures can be started before it's too late. Totally Vets produce a weekly facial eczema report during the risk period, this can be viewed on our website or you can sign up to have this emailed to you weekly.
It is vital to be aware of the risk situation, plan ahead and begin preventative measures early. Call into either branch of Totally Vets with your questions, or Read more...