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This article was published in 1961
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Facial Eczema
D. M. Flynn, B.V.Sc., Senior Veterinary Officer, Department of Agriculture, Victoria
Facial Eczema of sheep has been recognised in New Zealand since the end of the last century. The skin condition is not really an eczema but a reaction of sensitised skin to light, the bare areas around the face and the crutch being worst affected.
The skin damage can be quite serious, but the most important feature of the disease is the severe liver damage which always precedes the skin sensitivity. The liver damage is the diagnostic feature. Skin damage may or may not occur, probably depending on the type of pasture being grazed by the sheep.
Until recently Facial Eczema was regarded exclusively as a New Zealand disease. In the autumn of 1956 a serious outbreak of Facial Eczema occurred for the first time in Australia in East Gippsland in Victoria, the outbreak area being elliptically shaped, approximately 90 miles long by 40 miles wide, broadly stretching between the towns of Rosedale and Lakes Entrance.
The disease again appeared in the same area in a much more serious form in the autumn of 1959, when it was estimated that 10,000 sheep died during the following winter as a result of that outbreak. The autumn of 1960 again saw an outbreak, in the same area, which, while not so serious as that of 1959, affected sheep and cattle, particularly in some irrigation areas which had previously been regarded as relatively safe.
The observation during the autumn of 1960 that the disease is likely to be important in cattle, particularly those grazing on irrigation areas, raises the question as to how serious this disease is likely to become.
The earliest signs which are observed in a flock of sheep affected with this disease are shaking of the head, raising the head, sniffing, stamping the fore feet, an opacity of the eyes and reddening of the conjunctiva which can be mistaken for pink eye. Within a day or two the ears swell and droop and the skin of the lips and face commences to swell. As the disease progresses the skin dies and forms a crust through which serum frequently oozes. Deaths can occur at this stage, with acute severe liver damage and inability of the animal to graze. Affected sheep normally seek shade.
There is no evidence of any age susceptibility to the disease nor of any breed susceptibility. Young sheep tend to be the first to show the condition in the mob and while many sheep may recover, breeding ewes which have passed through an outbreak are usually regarded as not being an economic unit to retain, as lambing appears to place too great a stress on animals with severly damaged livers.
By the time symptoms are seen in a mob the liver damage has already occurred and very little can be done to alleviate the condition. Owners who have had previous experience of the disease are usually prepared to send the mob for slaughter as soon as the first signs of the condition appear. There is some evidence here that high stocking rates appear to lead to more serious outbreaks of the disease, and that the condition is more serious on improved permanent pastures than on top-dressed native pastures.
In New Zealand attempts have been made over a number of years to predict outbreaks of facial eczema by observing the weather conditions which occur during each autumn and considerable information has been gathered on the types of weather which favour the growth of the fungus. Accurate soil temperature and day to day weather records were kept in the area during last autumn and our experience here is that the fungus will grow vigorously under weather conditions and temperatures outside the expected range based on New Zealand experience.
There is no vaccine available and by the time symptoms are noticed the liver damage has already occurred. There does not appear to be any effective treatment and early slaughter of animals is the only means of reducing the losses which can occur. Work in New Zealand suggests that some fodder crops are not likely to harbour the fungus and would be relatively safe grazing during danger periods in the autumn. The alternatives to this, which are used in New Zealand, are that in danger periods the sheep are enclosed in a small area and fed hay until the pastures are judged to be safe. The limited experience which we have in Victoria has suggested that sheep allowed to run on the whole property are much less likely to suffer damage than sheep which are heavily stocked in one or two paddocks. Owners who have been able to spread their sheep out in unimproved bush country during toxic periods have been successful in escaping the disease.
Prior to 1958, New Zealand research had concentrated on an endeavour to discover the toxic principle which was believed to be present in the autumn growth of ryegrass in certain seasons. It was believed that the grazing of this toxic pasture led to the liver damage. Our experience in 1956 showed that Facial Eczema could occur on a whole range of pasture types, from top dressed native pastures to sown down permanently improved New Zealand ryegrass strain pastures.
In 1958 a discovery was made in New Zealand which revolutionised the thinking on this disease. It was found that there were present in toxic pastures the spores of a fungus. The classification of this fungus has caused some controversy throughout the world, the latest name given to it being Pithomyces chartarum. Isolates of this fungus from toxic pastures in New Zealand were grown in the laboratory and when fed to lambs, guinea pigs and rabbits produced a liver damage which was regarded as typical of Facial Eczema.
Prior to the spring of 1960 the research programme in Victoria had been directed to field observations and pasture surveys of the area where the disease occurred, observations of the disease itself, together with the isolation of the fungus from toxic pastures, reproduction of the disease in sheep in the laboratory and more recently, a
With this work as a guide, when the 1959 outbreak occurred in Victoria pasture samples were examined for the presence of this fungus and isolations were made and grown in the Biology Laboratory of the Victorian Department of Agriculture at Burnley. Some of these isolates have since been examined in New Zealand and are considered to be distinct from the New Zealand strains. One of these isolates produced typical liver lesions of Facial Eczema when fed to a lamb at the Veterinary Research Institute at Parkville.
Prior to the Spring of 1960 the research programme in Victoria had been directed to field observations and pasture surveys of the area where the disease occurred, observations of the disease itself, together with the isolation of the fungus from toxic pastures, reproduction of the disease in sheep in the laboratory and, more recently, a survey of the State to determine whether the fungus grows in areas outside Gippsland and whether Facial Eczema occurs outside the previous defined area. By the use of spore trapping machines during last autumn it was established that the fungus was widespread in this State and since then an appeal for specimens from all sheep showing photo-sensitisation has brought to light evidence that the disease is occurring, in a less serious form, in many areas of Victoria.
At the present time a Facial Eczema research station is being developed on known toxic pastures in East Gippsland. The programme of research in this field station includes a study of the growth of the fungus under our conditions and an attempt to define the precise factors which encourage and inhibit the growth of this fungus. The field station includes an area of flood irrigation and provision for spray irrigation in order to study the effect of varying applications of water on the growth of the fungus. At the same time the disease itself will be studied in sheep grazing on the station and the field research will be backed up by an extensive programme of study of the fungus at the Biology Laboratory of the Department of Agriculture at Burnley, while work on the pathology of the liver damage and toxicity of the various strains of the fungus will be carried out at the Veterinary Research Institute.
Outbreaks in Victoria have occurred when early autumn rains of up to half an inch or more are followed by warm nights and mild days. This type of weather favours the growth of the fungus on the pasture and the sheep in seeking the green shoot accidentally swallow a considerable dose of fungal material and spores.
The most intriguing mystery about Facial Eczema in Australia is that the disease appeared for the first time in a serious form in the autumn of 1956 in an area in which sheep have been running since the year 1840 and in which top dressing and pasture improvement have been carried out since the early days of this century. It is impossible to believe that in all that time it was only in 1956 and again in 1959 and 1960 that suitable weather conditions occurred for the growth of the fungus. When this mystery is solved it is very likely that we will have solved the problem of Facial Eczema.