Managing Facial Eczema Season with Sheep

It is well known in the sheep industry that facial eczema is a risk during the summer and autumn months, especially in the north island of New Zealand. It was estimated that a large outbreak of facial eczema (FE) back in 1981 cost the industry over $266 million dollars (adjusted for inflation in 2019) (1), proving that whilst FE can often go unseen, it certainly does not go unnoticed. Knowing how to manage and prevent FE in different systems is therefore crucial. 

What is facial eczema?

FE is the result of sheep consuming spores from a fungus called Pithomyces Chartarum. When these spores enter the digestive tract, they release a mycotoxin called Sporidesmin, which enter the blood stream and travels to the liver. At the liver, the mycotoxins generate ‘free radicals’ which damage cell membranes and causes damage and blockages in the bile ducts. Blockages in the bile ducts result in a build-up of a waste by-product of chlorophyl breakdown, which can then overflow back into the bloodstream. When combined with sunlight it leads to the photosensitivity and skin irritation we closely link with facial eczema  (1) (2). 

What are the signs of FE in sheep?

Initial signs of FE in sheep include a high frequency of urination, restlessness, seeking shade, shaking of the head, and rubbing the head against hard surfaces such as fences and posts. It can further develop into drooping and redness of the ears, swollen eyes, and weeping and scab formation on any exposed skin areas. This skin can potentially become infected or fly blown(1). Long term, flocks are expected to have reduced fertility and fecundity, reduced growth rates in lambs and hogget’s, and an increased need for culling due to poor health and/or performance  (3). Overall, even mild facial eczema can have an impact on the short term and long term health and performance of sheep, and will undoubtedly have a financial impact in the long run.

When and where is Facial Eczema a risk?

Because FE has a fungal origin, the highest risk periods are during any warm moist conditions, however there is no specific defined trigger that can be used to determine risk without testing. An industry-wide rule of thumb is that risk increases when there has been 3 or more nights in a row with pasture temperatures over 12°C  (1) (2), , or when there has been warm weather with high humidity, with light rain or heavy over-night dews, creating a moist warm environment in the base of a pasture (1).  Additionally, there can be ‘hot spots’ across every farm which are of higher risk than others. These are typically areas with poor air movement, high sun exposure, and lots of dead matter in the pastures. In general, south-facing slopes, and areas exposed to the prevailing wind are lower risk, as they have more air movement, and less time in the sun  (1). However, to be certain of risk, you must do spore count tests. 
 
Working with a local vet to get spore counts done prior to grazing a paddock is the only way to be sure of the situation. If spore counts (number of spores per gram of pasture) are over 30,000, there is a significant risk. Ingestion of pasture with a low spore count over several days can be as damaging as ingestion of a high spore count pasture in one single day (1), so all risk is significant risk.

How to protect your flocks from Facial Eczema?

Once regular spore counts are being taken to understand the level of risk, the next step is to ensure sheep are protected. Whilst it is common to treat beef cattle via water, this is not as effective for sheep. Dosing the water with zinc for sheep is tricky as their water intake varies greatly with weather, milk production (dairy sheep) and if there are other natural water sources available (such as ponds puddles and creeks) therefore other methods are considered more reliable (4). There are several alternative options, each to suit different systems, and potentially can be used in conjunction with each other for extra protection if used correctly: 
  • Zinc boluses: a slow release ruminal bolus which provides protection for up to 6 weeks.
  • Drenching: Mixing Zinc Oxide and Water together and drenching regularly
  • Via feed (in a controlled manner only, such as in-shed feeding)
  • Spraying pastures with Zinc Oxide
  • Spraying pastures with fungicides
  • Lowering stocking rate so pastures aren’t grazed as hard, to avoid the pasture base where spore counts are highest
  • Using alternative pasture species: Pithomyces Chartarum fungus prefers ryegrass
  • Using alterative crops: Chicory, plantain and legumes are examples of safe crops
  • Breeding FE resistant sheep: a long-term solution. 
SealesWinslow can help: Zinc Oxide TS-99 is SealesWinslows zinc supplementation solution for sheep. It can easily be added to a mineral pellet, or a feed pellet to be provided via a controlled feeding system such as in-shed feeding for dairy sheep. 
 
For more information, speak with your local TSR. 
  1. Beef + Lamb New Zealand. Facing up to Facial Eczema. 2019.
  2. Dairy Australia. A Review of Facial Eczema (pithomycotoxicosis). 2013.
  3. Facial Eczema in hill country-Potential toxicity and effects on ewe performance. Sheath, Webby and Boom. s.l. : Proceedings of the New Zealand Society of Animal Production, 1987, Vol. 47.
  4. D’Amours, Genevieve. Facial Eczema – Monitoring that works. VetScript. 2020.