What is facial eczema?
Facial eczema (FE) is a disease of ruminant animals that is caused by the toxin sporidesmin. This toxin is released by the spores of a fungus that grows on the dead litter at the base of pasture and causes damage to the liver and bile ducts when ingested. This damage results in waste products of chlorophyll breakdown building up in the blood stream causing the clinical symptoms that we see. For every animal that has clinical signs of FE there are many more that are being affected by subclinical FE and it is this group that contribute to the greatest production losses for farmers.
The fungus will produce spores when humidity is high and the minimum temperature of the grass is 12 degrees for at least two nights in a row. We typically see weather conditions like this from January to May, but this can vary from year to year.
Sheep are considered the most vulnerable, followed by dairy cattle. Beef cattle, goats, deer and alpacas can all also be affected by FE.
What are the symptoms?
Symptoms of FE in sheep include:
- Photosensitivity – animals will be restless and seek shade. They will develop skin lesions that look like sunburn.
- Droopy ears and swollen eyes. Sheep may rub their head on fence posts causing irritated areas of skin to bleed.
- Skin lesions may become infected and/or flyblown
- Jaundice (yellow mucous membranes)
- Rapid weight loss
- Death in severe cases
- Reduced fertility and fecundity (subclinical)
- Ill thrifty lambs (subclinical)
- Poor lamb growth rates (subclinical)
Symptoms of FE in cattle include:
- Photosensitive lesions will be seen on areas of pale or hairless skin. Affected areas in cows include the udder, teats, skin on the back, front of the legs, ears, eyes and nose.
- Death in severe cases
- Reduced milk production (subclinical)
- Weight loss or decreased weight gain in young stock (subclinical)
How do I know if my stock are at risk?
FE can affect all farms whether they be large commercial farms or lifestyle blocks. Monitoring the spore count of your pastures is the recommended way to determine your farms risk. South Wairarapa Vets offer an in-house spore counting service and you can find information below on how to collect a pasture sample for spore counting.
What can be done to prevent FE?
There are multiple different prevention methods that can be put in place. These vary in terms of cost, time and staff required to implement them as well as length of protection they provide.
Some prevention methods include:
- Zinc dosing – this can be done via several methods such as drenching, application of boluses, dosing the water supply and adding zinc to the feed.
- Fungicide sprays – these need to be applied before the risk period as they will not kill existing spores. If applied properly fungicide sprays can provide protection for 4-6 weeks.
- Breeding for tolerance – FE tolerance is known to be very heritable in sheep and cattle. Using rams that have been bred for FE tolerance traits can help increase the tolerance of your flock.
- Grazing management – such as not grazing animals on pasture that is a greater risk of high spore counts such as sheltered flat paddocks. Light rotational grazing strategies and replacing affected pasture with grass types that do not support growth of the fungus.
We recommend that you consult with a veterinarian to figure out a prevention plan that best suits the needs of your farm and business. Similarly, if you suspect your animals have facial eczema contact your vet to discuss treatment options.
If you require any more information give us a ring on 06 377 0464.
How to collect a pasture sample for spore counting
1. Select a paddock that you wish to monitor. We suggest you monitor four paddocks for a farm, one paddock in a lifestyle block. 2. Cut a handful of grass with scissors or a knife, at 1cm above the ground level. Place the sample in a clean plastic or paper bag. 3. Repeat procedure at least 10 times, from random areas at least 10 metres apart in the paddock. Avoid only sampling parts of the paddock sheltered by trees and hedges and contaminating sample with soil and roots. 4. We need 100g of grass (one bread bag full) per monitoring site. 5. Store in the fridge until taken to clinic. 6. Repeat sampling weekly in the same paddock, take samples on the same path across the paddock.
When counts get close to 20,000 per gram, you should take action.
Fungicide sprays are ideally applied before spore counts hit 20,000, when grass is green and growing.
Zinc dosing can be started at 20,000 to prevent liver damage.
If your spore counts are of concern our technician will pass your results on to a veterinarian who will ring you to discuss a prevention plan to suit your farm.