What is Facial Eczema?
Alpaca are very susceptible to facial eczema, even more so than sheep and cattle! So what is Facial eczema? Facial eczema is a common and potentially dangerous disease that is common in the North island during the summer and autumn months.
It is a disease caused by the ingestion of spores produced by a fungus called Pithomyces Chartarum. The spores can be found in pasture, especially in the dead leaf litter, and they contain a toxin called sporidesmin. When grass is broken down in the stomach, the toxin is absorbed into the blood stream. The toxin then gets processed in the liver and as the toxin is broken down it produces free radical compounds that cause death of liver cells. The liver is then unable to function at its normal capacity to process normal metabolic compounds, leading to a build up in the blood stream. Some of these compounds react with UV light and cause photosensitivity in alpacas.
This sensitivity to sunlight causes clinical signs such as shade seeking behavior, inflammation and crusting of the skin and sunburn usually on the face and unpigmented areas of the body. Other signs to look for include ill thrift, reduced milk output, reproductive issues and death.
When are Alpaca at risk?
Summer and Autumn following a period of warm and wet weather are periods that the fungus produces a high number of spores. Spore counts can increase dramatically in a short time period.
A blood test for liver enzyme GGT can be done to measure the level of liver damage caused by facial eczema.
Prevention is vital with facial eczema once acquired liver damage can be irreversible.
- Spore counts can be done on pasture to see how at risk your pasture is. Some areas of a farm can be more at risk than other areas. Paddocks known to be high risk paddocks can be avoided during peak periods. Because alpacas are more sensitive, the reported spore count levels that are safe for sheep are often too high for alpacas.
- Fungicides can be sprayed on pasture to reduce the amount of fungi and therefore the amount of spores produced.
- Alpacas can be supplemented with zinc. Zinc reduces the amount of free radicals made when sporidesmin toxin is metabolized in the liver, reducing the death of liver cells. Supplementing zinc in a water source is usually ineffective in alpacas due to their drinking habits. Slow releasing Zinc bullets are also not appropriate for alpacas because they are broken down in the stomach too rapidly compared to sheep and cattle. The best zinc supplement for alpacas would be Zinc oxide powder sprinkled into feed or using the premade pellets for alpacas. The Zinc oxide can make the feed quite bitter, so adding molasses may help with the bitter taste!
Anna MacKenzie BVSc