Facial eczema - the importance of prevention
Facial eczema (FE) was a significant problem last year and the conditions are shaping up for a repeat of the same again this year.
The ideal conditions for FE are grass minimum temperatures above 120C and moisture in the form of rain or high humidity. The environment on-farm makes a difference as well with north-facing paddocks, shelter (prevents drying) and plenty of dead matter (litter) in the pasture base - i.e. close to the ground - creating ‘hot spots'.
What animals are at risk?
Fallow deer, sheep and alpacas are the most susceptible, followed by dairy cattle (including weaners), beef cattle and red deer with goats being the least at risk. Horses are not affected.
Last year small block holders were badly hit as preventative measures such as zinc in the water supply are not routinely used. An alternative option is discussed later under treatment and prevention.
What are the symptoms?
The most obvious symptoms of FE are due to photosensitivity: restlessness; shade-seeking behaviour; and reddening of non-pigmented skin and areas without much hair/wool cover. Sheep and goats will commonly develop a swollen face and ears with the ears tending to droop. The onset of photosensitivity is usually preceded by a drop in milk yield in affected dairy cows. For all species, there is leakage of serum and scab formation associated with the worst lesions. Signs in alpacas are similar to sheep but as they are stoic animals and do not readily display discomfort; a dead animal may be the first sign of a problem. A blood test can be used to screen for potential damage during periods of risk.
Spore counts
We strongly recommend that you check the weekly spore counts on the Totally Vets website (these can be provided as a weekly email report) but take preventative measures before these get too high. Spore counts above 25,000/g are dangerous; however lower counts are not completely risk-free.
Treatment and prevention
As the saying goes, ‘prevention is better than cure' and this is particularly the case with FE. Start zinc-dosing before pastures become dangerous as this gives much better protection than crisis-dosing once the counts rise.
The methods of prevention are based around:
- 1. Slow-release capsules (‘Time Capsules')
- 2. Zinc sulphate in the drinking water
- 3. Zinc oxide in the feed or by drenching
- 4. Grazing management and crops
- 5. Pasture fungicide spray
Capsules are best suited for use in sheep and in situations where water treatment is not possible. Capsules are ideal for lifestyle blocks and run-offs, last for 6 weeks and can be repeated if necessary. Totally Vets offers a service to administer these for those not familiar with their use.
Zinc sulphate in the drinking water is commonly used where an inline dispenser or header tank supplies the water troughs. Information regarding the amounts used and how to manage each method is best provided on a case-by-case basis, so contact Totally Vets to discuss these. Water treatment is not as effective for sheep as it is for cattle.
Pastures that have been well grazed in spring and early summer will have less dead matter and provide safer grazing in the autumn. Legumes and plantain are safer than grasses. Topping paddocks in summer will probably increase the risk latter on.
Finally, lowering stocking densities and leaving higher residuals will reduce the risk of animals grazing down to the pasture base.
Fungicide sprays must be applied before the spore count rises and have no effect on already dangerous pasture. Sprayed pastures remain ‘safe' for up to 8 weeks but re-application of the spray is required after heavy rain.
