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ABOUT FACIAL ECZEMA
The following material has been collated and adapted from several sources, including a handout prepared by Dr Geoff Neal of Manawatu Veterinary Service for a seminar presented at an Alpaca Assn Focus Farm seminar on Facial Eczema.
What is Facial Eczema?
Facial eczema is a disease process caused by a fungus, Pithomyces chartarum, that grows in the dead litter at the base of pasture in warm, moist conditions, and produces spores as part of its reproductive process. The spores have a toxic compound called sporidesmin that causes disease.
When ingested by grazing animals, including alpacas, the spores are broken down and the toxin is absorbed into the bloodstream. The toxin undergoes an enzyme oxidation and reduction pathway within the liver cells, the by-products of which are oxygen free radicals that damage the liver and bile ducts.
The damaged liver cannot rid the body of wastes, and a breakdown product of chlorophyll builds up in the blood causing sensitivity to sunlight, which in turn causes inflammation of the skin on areas most exposed to the sun, including the muzzle, ears etc.
The sunburn is often accompanied by watery swelling of the underlying tissues, resulting in drooping ears and puffy eyes and face. Jaundice (yellowing of mucous membranes) and rapid weight loss may also be seen at this stage. Some animals can recover from the acute phase, but they may take many months to regain condition.
Badly damaged liver tissue will never regenerate. Chronic wasting and/or death may occur at the time of damage or months later when the animal is under stress (e.g. birthing). The most serious outcome of FE is complete liver failure, and death.
When is the greatest risk period for Facial Eczema and why?
The disease is most common from February to May. The fungus needs warm, moist conditions for growth and. may reach dangerous levels on pasture following humid periods of 72 hours or more during which the temperature at ground level does not fall below 120C, with atmospheric moisture equivalent to 5 mm rain. Heavy dews and high relative humidity can exert the same moisture requirement as rain itself.
The fungus only grows on dead vegetable matter, not green growing grass, and so in the Summer and Autumn, when grass is dead or has a lot of dead litter at the base, is when the spores are most prevalent. Topping of pasture will increase the amount of dead leaf litter at the base of the pasture. Two "danger" periods up to two or three weeks apart can raise the spore count to significantly high levels – certainly enough to cause disease.
Given suitable temperature and moisture conditions, the fungus grows in "clusters" on the paddock, rather like mushrooms, but is normally not visible to the naked eye. It multiplies by producing millions of spores which are coated with the toxin sporidesmin. Freshly produced spores are the most toxic; if fungal growth stops after a change in the weather, the residual spores on the pasture lose their toxicity within one or two weeks.
The fungus will grow on most pasture plants, but it grows best on perennial ryegrass. It grows in the dead pasture litter at the base of the plants; most toxic spores are found in the bottom 25 mm of the pasture. When the fungus reaches toxic levels, animals grazing short pasture at high stocking rates are at greatest risk.
Why and how can alpacas get Facial Eczema?
Of all the grazing ruminant animals in NZ, alpacas are probably most in danger from FE. They have little or no natural inbred resistance, and can easily contract this disease. Alpacas are more sensitive to the FE toxin than sheep, cattle, deer and goats. It has been estimated that they can become ill when the spore count is at just 20% of the level at which sheep will become infected.
Alpacas habitually forage close to the ground, and, because the FE fungus grows on the dead part of the grass towards the root (with perennial ryegrass pasture presenting most risk due to its ability to produce dead plant material) poor or inadequate grazing substantially increases the FE risk to your alpacas. Over-stocking and hard grazing are obvious hazards.
How can you prevent alpacas from getting Facial Eczema?
The basis of prevention of facial eczema is good management. There are two main ways in which the FE risk can be managed: monitor and manage the environment; deliver preventative care directly to your alpacas.
The first step is to monitor and assess the environmental risk posed to your alpacas. This involves monitoring the environmental conditions required for the growth of the fungus, and monitoring the levels of spores in the pasture.
Monitoring the environmental conditions may be done simply and visually, or by checking regional weather data indices, or by directly taking on-site measurements of temperature, humidity and rainfall.
Then, when a danger period is imminent, the following management alternatives are available, all of which will help to minimise the intake of infected pasture.
Summer-growing crops are generally safer than pastures, and stock should be given as much access to these as possible where they are available. In pasture, kikuyu, chicory, plantain and red clover are safer than ryegrass.
Spore level monitoring can be done either by using regional or local information from sources such as AgriQuality, MAF, your local vets, newspapers etc. as a guide, or by directly counting the spore levels in your paddocks.
The main issue with spore count levels is interpretation of the risk. The spore levels described as safe for other livestock species are not necessarily – and most likely are not - safe for alpaca to graze. As to exactly what is a safe level of spore exposure for alpaca is not known and very difficult to assess.
Long-term consumption of low levels of spores can be as dangerous as short-term consumption of a high spore level because the effects of the toxin on the liver are cumulative.
Reducing the levels of spores on the pasture involves altering the environmental conditions for the fungus. Use pasture control to avoid excessive dead material at the pasture base (soil level), thus reducing the available surface area for the fungus to grow on. Although topping can help control grass quality, it should preferably be avoided as it will also increase dead matter at the pasture base.
The easiest way to stop the fungus growing is to kill the fungus off by spraying with a fungicide spray. There are numerous products on the market, however most must be administered by a certified Approved Handler. The point often missed about fungicide spraying is that it works best when there are minimal spores present, and when a period of rapid fungal growth is anticipated. Fungicide sprays kill the fungus not the spores. The length of protection gained from spraying is usually 6-8 weeks depending on the product used and the application rates.
Most fungicide sprays for Facial Eczema are only 60-70% effective so additional protection is needed to ensure the safety of the animals grazing the pasture.
The importance of Zinc in the prevention of FE
Whether or not you choose or can afford to spray your paddocks with a fungicide, it is vitally important to deliver preventative care directly to your alpacas by adding zinc to their diet. The purpose of this is to stop the toxin from damaging the liver should spores be consumed by the animal.
Zinc oxide is used to help protect ruminant animals against Facial Eczema because it disrupts the oxidation-reduction pathway that releases the oxygen free-radicals which cause the liver damage. Zinc oxide powder is either made up into a slurry and drenched directly into the animal or it is incorporated into feed and fed as a supplement.
The drenching of alpaca with zinc oxide slurries is difficult and would have to be repeated every 3-4 days to be effective. (A cautionary note: Never drench animals, including alpaca, with zinc sulphate slurries. You will likely kill the animal you are trying to protect.)
Incorporation of zinc oxide into feeds is the easiest way to get alpacas to consume zinc. You can sprinkle the powder over feed or use commercially made alpaca pellets containing zinc oxide.
Zinc pellets are simple and easy to administer, but they cannot be suddenly thrust at your alpacas; they won’t like them. You need to introduce them gradually, so that your animals can become accustomed to the taste of the zinc.
If your alpacas are not used to eating pellets at all, you should first introduce a small quantity of non-zinc pellets into their diet, building up to a cupful (200-250gm) every day. Then, after a few days, begin to introduce zinc pellets by mixing in 25%, then 33%, 50%, 66%, 75% and finally, after doing that gradually over 2 weeks, they will happily accept 100% zinc pellets. You will also need to disguise the metallic, slightly bitter taste of the zinc to make it palatable. Molasses works quite well, as does a fermented animal feed such as FibreEzy mixed with a little Lucerne chaff.
Be sure to feed sufficient pellets to each alpaca every day to provide adequate protection. The required level of zinc for protection from Facial Eczema is 2g elemental zinc (2.5g zinc oxide) per 100kg liveweight per day. A 250gm serving of zinc pellets should provide adequate protection for a 75kg animal.
You must limit the time you add zinc to your alpaca’s diet. Excessive consumption of zinc for extended periods of time in any ruminant species can lead to pancreatic disease and copper deficiency. The recommended maximum continuous zinc supplementation period is 100 days. Ideally you should start feeding zinc to your alpacas in mid-January, and cease feeding it by the end of April.
What are the signs of Facial Eczema in alpacas?
Alpacas are very stoic animals and may not show the subtle early signs that other species do until the liver damage is very severe. Because as a species they are very susceptible to FE, early diagnosis and treatment is highly recommended.
Not all animals affected with FE actually show physical signs (i.e. clinical FE) although liver damage (i.e. subclinical FE) has already occurred. If clinical signs are apparent, they will not be seen until between seven and 20 days of pick-up of the toxic spores from the pasture.
Although a diagnosis of facial eczema can be made based on clinical signs in the live animal, that is not very accurate, as there are other diseases that can resemble Facial Eczema in the early stages e.g. Ryegrass staggers, rickets.
The symptoms that may usually be seen in other species affected with Facial Eczema include:
In a live animal a diagnosis is usually confirmed by a blood test looking at the level of an enzyme called gamma glutamyltransferase (GGT). GGT is released by the liver and biliary cells when they are damaged and can result in dramatic increases in the GGT levels. Interpretation of GGT levels is quite difficult for several reasons, one of which is that the enzyme has a long breakdown time (half-life) in the body.
In a dead animal, the diagnosis can be made on post-mortem examination and confirmed by laboratory examination of the liver under a microscope.
How can you treat Facial Eczema in an alpaca?
The simple answer is, with great difficulty, and maybe not at all. Facial Eczema causes permanent liver damage that may heal to a certain degree, but never back to normal. Alpacas with mild symptoms can be nursed along with supportive care, reduced protein feeds, and shade. Complete darkness is best.
The very first thing to do if you suspect an FE infection is call your vet – urgently.
You may aid your infected alpaca to a slow, time-consuming and only partial recovery with these measures:-
In summary, manage your pastures adequately, be aware of spore count levels, monitor your alpacas, start zinc supplementation early and contact a vet as soon as possible if you suspect any animal is affected.
The following material has been collated and adapted from several sources, including a handout prepared by Dr Geoff Neal of Manawatu Veterinary Service for a seminar presented at an Alpaca Assn Focus Farm seminar on Facial Eczema.
What is Facial Eczema?
Facial eczema is a disease process caused by a fungus, Pithomyces chartarum, that grows in the dead litter at the base of pasture in warm, moist conditions, and produces spores as part of its reproductive process. The spores have a toxic compound called sporidesmin that causes disease.
When ingested by grazing animals, including alpacas, the spores are broken down and the toxin is absorbed into the bloodstream. The toxin undergoes an enzyme oxidation and reduction pathway within the liver cells, the by-products of which are oxygen free radicals that damage the liver and bile ducts.
The damaged liver cannot rid the body of wastes, and a breakdown product of chlorophyll builds up in the blood causing sensitivity to sunlight, which in turn causes inflammation of the skin on areas most exposed to the sun, including the muzzle, ears etc.
The sunburn is often accompanied by watery swelling of the underlying tissues, resulting in drooping ears and puffy eyes and face. Jaundice (yellowing of mucous membranes) and rapid weight loss may also be seen at this stage. Some animals can recover from the acute phase, but they may take many months to regain condition.
Badly damaged liver tissue will never regenerate. Chronic wasting and/or death may occur at the time of damage or months later when the animal is under stress (e.g. birthing). The most serious outcome of FE is complete liver failure, and death.
When is the greatest risk period for Facial Eczema and why?
The disease is most common from February to May. The fungus needs warm, moist conditions for growth and. may reach dangerous levels on pasture following humid periods of 72 hours or more during which the temperature at ground level does not fall below 120C, with atmospheric moisture equivalent to 5 mm rain. Heavy dews and high relative humidity can exert the same moisture requirement as rain itself.
The fungus only grows on dead vegetable matter, not green growing grass, and so in the Summer and Autumn, when grass is dead or has a lot of dead litter at the base, is when the spores are most prevalent. Topping of pasture will increase the amount of dead leaf litter at the base of the pasture. Two "danger" periods up to two or three weeks apart can raise the spore count to significantly high levels – certainly enough to cause disease.
Given suitable temperature and moisture conditions, the fungus grows in "clusters" on the paddock, rather like mushrooms, but is normally not visible to the naked eye. It multiplies by producing millions of spores which are coated with the toxin sporidesmin. Freshly produced spores are the most toxic; if fungal growth stops after a change in the weather, the residual spores on the pasture lose their toxicity within one or two weeks.
The fungus will grow on most pasture plants, but it grows best on perennial ryegrass. It grows in the dead pasture litter at the base of the plants; most toxic spores are found in the bottom 25 mm of the pasture. When the fungus reaches toxic levels, animals grazing short pasture at high stocking rates are at greatest risk.
Why and how can alpacas get Facial Eczema?
Of all the grazing ruminant animals in NZ, alpacas are probably most in danger from FE. They have little or no natural inbred resistance, and can easily contract this disease. Alpacas are more sensitive to the FE toxin than sheep, cattle, deer and goats. It has been estimated that they can become ill when the spore count is at just 20% of the level at which sheep will become infected.
Alpacas habitually forage close to the ground, and, because the FE fungus grows on the dead part of the grass towards the root (with perennial ryegrass pasture presenting most risk due to its ability to produce dead plant material) poor or inadequate grazing substantially increases the FE risk to your alpacas. Over-stocking and hard grazing are obvious hazards.
How can you prevent alpacas from getting Facial Eczema?
The basis of prevention of facial eczema is good management. There are two main ways in which the FE risk can be managed: monitor and manage the environment; deliver preventative care directly to your alpacas.
The first step is to monitor and assess the environmental risk posed to your alpacas. This involves monitoring the environmental conditions required for the growth of the fungus, and monitoring the levels of spores in the pasture.
Monitoring the environmental conditions may be done simply and visually, or by checking regional weather data indices, or by directly taking on-site measurements of temperature, humidity and rainfall.
Then, when a danger period is imminent, the following management alternatives are available, all of which will help to minimise the intake of infected pasture.
- Shift stock to the longest pasture possible, and try to avoid very close grazing.
- Avoid paddocks cut for hay or lately-topped. These are likely to be more risky because of greater quantities of pasture litter.
- In general, paddocks sheltered by windbreaks or hills are more dangerous and should be avoided.
- Feed hay or other supplements to preserve ground feed and minimise close grazing of pasture.
Summer-growing crops are generally safer than pastures, and stock should be given as much access to these as possible where they are available. In pasture, kikuyu, chicory, plantain and red clover are safer than ryegrass.
Spore level monitoring can be done either by using regional or local information from sources such as AgriQuality, MAF, your local vets, newspapers etc. as a guide, or by directly counting the spore levels in your paddocks.
The main issue with spore count levels is interpretation of the risk. The spore levels described as safe for other livestock species are not necessarily – and most likely are not - safe for alpaca to graze. As to exactly what is a safe level of spore exposure for alpaca is not known and very difficult to assess.
Long-term consumption of low levels of spores can be as dangerous as short-term consumption of a high spore level because the effects of the toxin on the liver are cumulative.
Reducing the levels of spores on the pasture involves altering the environmental conditions for the fungus. Use pasture control to avoid excessive dead material at the pasture base (soil level), thus reducing the available surface area for the fungus to grow on. Although topping can help control grass quality, it should preferably be avoided as it will also increase dead matter at the pasture base.
The easiest way to stop the fungus growing is to kill the fungus off by spraying with a fungicide spray. There are numerous products on the market, however most must be administered by a certified Approved Handler. The point often missed about fungicide spraying is that it works best when there are minimal spores present, and when a period of rapid fungal growth is anticipated. Fungicide sprays kill the fungus not the spores. The length of protection gained from spraying is usually 6-8 weeks depending on the product used and the application rates.
Most fungicide sprays for Facial Eczema are only 60-70% effective so additional protection is needed to ensure the safety of the animals grazing the pasture.
The importance of Zinc in the prevention of FE
Whether or not you choose or can afford to spray your paddocks with a fungicide, it is vitally important to deliver preventative care directly to your alpacas by adding zinc to their diet. The purpose of this is to stop the toxin from damaging the liver should spores be consumed by the animal.
Zinc oxide is used to help protect ruminant animals against Facial Eczema because it disrupts the oxidation-reduction pathway that releases the oxygen free-radicals which cause the liver damage. Zinc oxide powder is either made up into a slurry and drenched directly into the animal or it is incorporated into feed and fed as a supplement.
The drenching of alpaca with zinc oxide slurries is difficult and would have to be repeated every 3-4 days to be effective. (A cautionary note: Never drench animals, including alpaca, with zinc sulphate slurries. You will likely kill the animal you are trying to protect.)
Incorporation of zinc oxide into feeds is the easiest way to get alpacas to consume zinc. You can sprinkle the powder over feed or use commercially made alpaca pellets containing zinc oxide.
Zinc pellets are simple and easy to administer, but they cannot be suddenly thrust at your alpacas; they won’t like them. You need to introduce them gradually, so that your animals can become accustomed to the taste of the zinc.
If your alpacas are not used to eating pellets at all, you should first introduce a small quantity of non-zinc pellets into their diet, building up to a cupful (200-250gm) every day. Then, after a few days, begin to introduce zinc pellets by mixing in 25%, then 33%, 50%, 66%, 75% and finally, after doing that gradually over 2 weeks, they will happily accept 100% zinc pellets. You will also need to disguise the metallic, slightly bitter taste of the zinc to make it palatable. Molasses works quite well, as does a fermented animal feed such as FibreEzy mixed with a little Lucerne chaff.
Be sure to feed sufficient pellets to each alpaca every day to provide adequate protection. The required level of zinc for protection from Facial Eczema is 2g elemental zinc (2.5g zinc oxide) per 100kg liveweight per day. A 250gm serving of zinc pellets should provide adequate protection for a 75kg animal.
You must limit the time you add zinc to your alpaca’s diet. Excessive consumption of zinc for extended periods of time in any ruminant species can lead to pancreatic disease and copper deficiency. The recommended maximum continuous zinc supplementation period is 100 days. Ideally you should start feeding zinc to your alpacas in mid-January, and cease feeding it by the end of April.
What are the signs of Facial Eczema in alpacas?
Alpacas are very stoic animals and may not show the subtle early signs that other species do until the liver damage is very severe. Because as a species they are very susceptible to FE, early diagnosis and treatment is highly recommended.
Not all animals affected with FE actually show physical signs (i.e. clinical FE) although liver damage (i.e. subclinical FE) has already occurred. If clinical signs are apparent, they will not be seen until between seven and 20 days of pick-up of the toxic spores from the pasture.
Although a diagnosis of facial eczema can be made based on clinical signs in the live animal, that is not very accurate, as there are other diseases that can resemble Facial Eczema in the early stages e.g. Ryegrass staggers, rickets.
The symptoms that may usually be seen in other species affected with Facial Eczema include:
- Irritation and restlessness
- Skin swelling
- Crusting and oozing (often around nose and ear margins)
- Abortion
- Sudden death
In a live animal a diagnosis is usually confirmed by a blood test looking at the level of an enzyme called gamma glutamyltransferase (GGT). GGT is released by the liver and biliary cells when they are damaged and can result in dramatic increases in the GGT levels. Interpretation of GGT levels is quite difficult for several reasons, one of which is that the enzyme has a long breakdown time (half-life) in the body.
In a dead animal, the diagnosis can be made on post-mortem examination and confirmed by laboratory examination of the liver under a microscope.
How can you treat Facial Eczema in an alpaca?
The simple answer is, with great difficulty, and maybe not at all. Facial Eczema causes permanent liver damage that may heal to a certain degree, but never back to normal. Alpacas with mild symptoms can be nursed along with supportive care, reduced protein feeds, and shade. Complete darkness is best.
The very first thing to do if you suspect an FE infection is call your vet – urgently.
You may aid your infected alpaca to a slow, time-consuming and only partial recovery with these measures:-
- Remove from contaminated pasture
- Provide shelter from sunlight, preferably into complete darkness
- Reduced protein feeds
- Use protective, nourishing skin creams (e.g. Filta-bac) to affected areas
- Minimize stress by making water and feed easily accessible to the animal
- Liver-specific supportive homeopathic treatments are available
In summary, manage your pastures adequately, be aware of spore count levels, monitor your alpacas, start zinc supplementation early and contact a vet as soon as possible if you suspect any animal is affected.