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This article was published in 1974
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Anthrax
by P.S. Green, B.V.Sc.
My first experience with Anthrax was in 1955 when I was appointed to the Flying Stock Inspector Service at Bourke and my involvement with the disease has continued to the present day. I make no claim to being an expert with regard to Anthrax, but over the years I have dealt with many cases and my observations may be of some help to those with less experience. I have lost count of the number of cases I have dealt with in sheep, but can only recall one case in cattle, two in pigs and three where humans and dogs were involved.
I am convinced that Anthrax is much more widespread in the so-called "Anthrax Belt" than is generally recognised. Over the years, I have frequently found the disease on properties where it has not previously been known to exist. In each case there had been small losses of stock from unknown causes over the years. In most such cases, the carcases were too decomposed when found for a diagnosis to be made and death was attributed by the owners to causes such as snake bite or lightning strike.
In the majority of cases, stock are found dead without having been seen sick. Bodies are frequently found on the bank of a tank, in camps or along sheep pads. Putrefaction is invariably rapid and in hot weather, within 48 hours the carcase has probably collapsed and looks as if it had been there for a week or more. Most text-books speak of tarry blood exuding from the anus, nose and mouth but in the hundreds of stock I have seen dead from anthrax, I have rarely found this to be so. Outbreaks of the disease usually occur in the hotter months and have often been associated with grass seed. It is not desirable to conduct a post-mortem examination for obvious reasons, but over the years I have opened several such carcases before diagnosing the disease. The most striking feature is the spleen, which is generally grossly enlarged; the spleen substance is broken down and really looks like raspberry jam. The blood does not clot or does so very slowly. It has been my custom for some years to incise the facial vein when Anthrax is considered a possibility. If the blood continues to flow then no P.M. is carried out, but smears are taken. As I do not wear gloves, I have frequently been exposed to infection; my faith in the value of undiluted Dettol for the hands has not been shaken, but I have experienced headaches, no doubt of a psychological nature, when anthrax has been confirmed in animals I have opened. I have been vaccinated against Anthrax and strongly recommend this to anyone who is likely to be exposed to the disease.
Where Anthrax has been confirmed and the owner or his employees have handled or skinned the carcases, they are naturally warned of the dangers and are advised to see their Doctor if they observe any unusual lesion on their hands or arms. In most cases, it is necessary to tell the Doctor that they have Anthrax. I am not casting any reflections on the Medical profession, but very few of them have seen the disease. I can recall at least three occasions where humans contracted the disease in outbreaks where I have been involved.
Vaccination normally brings an outbreak to a stop within a few days. It is cheap, safe, speedy and efficient. Earlier vaccines caused severe lameness and some deaths, but this has been overcome. Most owners in the Anthrax belt do not vaccinate their stock annually, but wait until deaths occur before taking any action. With the current vaccines I am not aware of the longevity of the protection induced, but I remember a case in the 1955-1960 era where two annual vaccinations did not provide protection for more than a further twelve months. Where stock die from Anthrax after having been vaccinated some months previously, it does tend to confuse the picture. In one such case the blood did clot; Glenfield confirmed the diagnosis, but commented that the smears were not typical of the disease. Speaking of smears, I normally take them from the facial vein or from the veins of the legs as this appears to give better results where the animal has been dead for more than a few hours.
On some occasions when I have diagnosed Anthrax, it has not been confirmed on the smears submitted. Glenfield, since 1972, has requested that swabs of peripheral blood be submitted in addition to air-dried blood smears. Where atypical organisms are found in smears, culture can then be undertaken to put the issue beyond doubt.
It is generally recognised that it is difficult to have Anthrax confirmed in pigs. Perhaps I have been lucky in that I have had two cases confirmed from two suspected outbreaks. Where pigs are sick or dead with swollen throats and they have had access to carcases in an Anthrax area, it is reasonable to assume that Anthrax is responsible. With pigs it is generally necessary to incise the throat swelling and make smears from the deeper tissues to confirm the disease. Pigs with Anthrax generally respond well to Penicillin therapy. One rather interesting outbreak was seen in pigs run in conjunction with a slaughter-house; several pigs had died and others were sick. Questioning revealed that the butcher had bought some wethers from a known Anthrax property, for sausage meat. One wether had died and had been thrown to the pigs. The rest of the sheep were slaughtered and minced for sausages. As a token gesture, the slaughter-house, mincing machine, etc., were "flamed" with a gas burner, but the local Medico and I waited in fear and trepidation for an outbreak of the disease in the local population. Luckily no such outbreak occurred.
Dogs appear to be rather resistant to Anthrax; affected animals are generally very swollen under the throat and may suffocate. As with pigs, Penicillin is of definite value and prompt treatment will save most dogs.
Circumstantial evidence would suggest that ploughing a paddock may bring Anthrax spores to the surface. I have known animals to die from Anthrax in such a paddock when they had been used to control the grass which had germinated. In one case the disease had not been recognised on the property for at least seventy years.
I hope that this rather rambling account has been of some interest and benefit to fellow members of the Association.