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This article was published in 1938
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.

"POST MORTEMS"

R. STEWART, B.V.Sc.

Mr. Chairman and Gentlemen;

I wish to thank you for permitting me the privilege of coming along and addressing you; it is one of the pleasures of the year so far as I am concerned, and I look forward to it with much interest. In selecting "Post-Mortems" as my address, my idea was not to load you up with a lot of pathological details but to offer ideas for discussion, either here or between yourselves at some other time, and to perhaps give you a few ideas on the approach to the post-mortem problem on the whole, rather than in reference to any particular disease.

Now, the first thing that occurs is that someone will ring and tell you that some animals are dead or dying, and they require your services. You are expected to go along and open the animal and make the post-mortem. Let us pause awhile. Before attempting the post-mortem, I suggest that you should get as many particulars and facts and circumstances regarding the case as it is possible to obtain. The operation on the cadaver is the last job of all, Commence with:

The History: in all forms of disease this is the most valuable guide of all to the diagnosis. Make your enquiries as exhaustive as possible, but see that every question is purposeful lest your witness tire of you. The history should include the number and variety of animals, feed given and available symptoms, duration of illness, and previous illnesses and mortality.

The next thing to note is the nature of the people themselves. Now, some people are well educated and some poorly. Some people do not read the labels on medicaments, others who believe they read the labels might read part of them and assume the rest. I have known instances where a medicament has been delivered we will say, in a gallon container and in the directions it says to place one pint in five gallons of water. They place the whole contents in the five (5) gallons of water and their sheep have died.

The Environment: When you go to a place, note the country, the people. etc.; in fact, every factor which may affect the problem in a general grouping of the situation. The type of animal and a general inspection of the sheds, outhouses and place as a whole is worth while. A person whose fences are all broken down is obviously a careless type on whose place animals dying would be likely to have certain types of diseases. The nature of the country and the presence of slaughterhouses, tanneries, mines and such like call for consideration. We have certain diseases which develop mostly in hilly country and other diseases which develop on plain country, such as Anthrax, which is seen usually on the flat country; Black Disease is mostly associated with hilly country. In this regard it is not so much the fact that the country is flat or hilly that makes for the type of disease, but rather some other factor which is in evidence on that particular type and class of country. For instance, out West, Fluke is seldom in evidence and thus there is much less risk of Black Disease; but in your preliminary examination it would not loom as largely as the possibility of Anthrax, which is mostly a disease of the flat country where particular types of grass grow and where there are grass seeds and spikes and prickles to lacerate the skin and mouth tissues of the animal.

Poison: People are often very careless in the use of Arsenic, Phosphorus and Strychnine, and other poisons. Nearly all stations use poisons. Some people store them in old sheds or in the wool shed and it falls on the floor and gets wet and eventually it gets through on to the soil and grass, etc. Mortalities occur and you trace the condition ultimately to such a source as this. I heard of one instance where phosphorus was the cause of deaths, and after hunting all over the place for the poison it was ultimately found that the tin of this poison for poisoning crows had fallen over (and) that it had run down into a bit of a gutter which, when a shower came became full of water, and the stock drank it and were promptly poisoned.

Again, the district itself and the prevailing diseases is of the greatest value. In certain districts, certain types of disease occur. These should be known to the investigator. Where the breeding of fat lambs is extensive, such districts are more subject to the disease of Pulpy Kidney than those in which fat lamb breeding is not undertaken. However, this is not because the sheep are more susceptible in one particular part than another; it is simply the result of intensive cultivation and the enforced feeding of the particular class of sheep for that particular objective.

I instanced you Anthrax occurring on the plains, Black Disease in hilly country and Pulpy Kidney where intensive cultivation and improved pastures are the vogue. We also have diseases such as Blackleg occurring mostly on hilly country. Blackleg has been proved to occur along river banks in the back country where they overflow but in a particular case Blackleg would at first not occur to your mind as a possibility of mortality.

Certain diseases are confined to certain classes of animal. Strangles is confined exclusively to horses, tetanus is rare in the dog; it is also rare in cattle, but it is extremely common in sheep, and again in this connection we have the association of ideas and circumstances. The sheep which have been subject to wounds such as shearing or marking may contract tetanus far more easily than sheep which are running simply in the paddock. Black Disease is practically confined to sheep but it may occur in cattle. Colics are mostly confined to horses, Pulpy Kidney in lambs, fluke in sheep and occasionally in cattle, worms in sheep, calves and foals, dysentery and pneumonia in pigs, pleuro, tuberculosis, prussic acid and hoven in cattle; so whether it is a sheep, cattle or horse, your mind runs along certain channels to the possible causes of the deaths.

Then again, Seasons have their influence. We all know that at certain periods of the year certain diseases become active. Anthrax is the disease which manifests itself in the summer but seldom in winter. The association with that is because in the particular country where Anthrax is rife the seeds are thorny and sharp and this occasions abrasions and wounds. Another connection with Anthrax is when the sheep are changing their teeth; here again, Anthrax is apt to make its appearance. Pulpy Kidney develops during the season when the lambs are growing, from the time they are a week old. It may occur at any time, but is most common then. Acute fluke develops in the late summer and autumn and chronic fluke through the winter. Black Disease is a disease which occurs practically through the summer and running into part of the winter, but finishes in late winter. It may appear at any period of the year, but is most common and has its peak period in March, April and May. Blackleg is the disease which occurs at its greatest virulence in April, May and June.

Then, diseases due or associated with some of the operations on the ear, such as dipping, marking. etc., occur at the appropriate period. When dipping is on, people complain that the sheep are dying, and one finds that they have been recently dipped. In connection with this, a lead is given to the possibility of scalding of the skin, pneumonia and inflammation of the bowels. Having formulated your various ideas on the subject and made suggestion to yourself as to the various possibilities and the nature of the property and country, and the types of diseases which are common to occur there, then you can tackle the postmortem. But having done as suggested, it is a wrong idea to attack your post-mortem with a preconceived idea of what the cause is going to be. You want to attack it with an absulutely clear and unbiased mind. What you have done in the early part is suggestive of things that may be, but do not let this influence you in the post-mortem.

As regards the actual post-mortem, from the point of view of the Stock Inspector, I think that you gentlemen are par excellence in this regard. I was privileged on one occasion to see a Stock inspector make a post-mortem. It was a pleasure and a revelation to me to see the business-like manner in which he conducted it, running the intestines out from end to end, collecting specimens, and the whole job was thoroughly and efficiently done, leaving nothing to the imagination, and I feel sure that the example I saw was one that is common to all you gentlemen. So on the actual making of the post-mortem I will not touch, but I would like to speak regarding the generalisation of appearances. There are certain classes of diseases which create certain trains of appearances, just the same as in the analysis of a chemical article. The chemist, after certain preliminary tests are made, commences to treat the article to be analysed and puts the various solutions into certain groups, metals and non-metals. Having got them into these groups, he commences to put them to special tests to determine which particular class of chemical is present. In our work, one of the common groups is that which causes "enteritis." Almost all forms of metallic poisoning will create the same set of post-mortem appearances in general. For instance, if cattle eat arsenic they get inflammation of the second, third and fourth stomach. The intestines are inflamed, the tissues are engorged with blood and the lung shows considerable redness and inflammatory reaction, but not necessarily pneumonia. Now, if you have poison with mercury or any other type of metal, you will find practically similar appearances present, therefore you cannot determine, purely from the post-mortem, whether it is poisoning by phosphorus or mercury or arsenic. When it comes to the symptoms which you perhaps investigated before the post-mortem, you find that here again they run on the same lines. You get colic, lying-down weakness, scouring and then death, and it does not tell you which particular class it is.

These symptoms and appearances are consistent with those related to metallic poison, of which arsenic may be cited as an example, and are manifested in the animal as inflammation of the bowels in particular. Then we have "toxic" diseases, which are caused by the poisons of microbes. The "toxic" diseases are produced by virulent poisons that circulate through the system and set up a set of symptoms and a set of post-mortem appearances which are more or less related and consistent one with the other. Let us look, for instance. at Black Disease, which is caused by a microbe located in the liver and which produces a virulent poison which circulates through the system, and on post-mortem we find fluid in the bag around the heart and in the abdominal cavity and an inflamed liver. People living in Black Disease country say the animal has died of Black Disease because he has fluid around the heart and because we have fluid in the peritoneal cavity, generally of a yellow nature. Black Disease is the cause because they have that particular appearance. Then you go through the various organs and you lay open the inside lining of the pericardium, the outside covering of the heart and you will find the blood vessels full of blood and minute blood clots under the tissue. The examination of the intestines very often shows only slight appearances as regards diseases when one compares the appearancem determined in connection with metallic poisoning described above. Yet there are appearances of inflammation, especially in relation to the blood vessels of the part. Another factor which carries coneiderable weight in the lay mind is that the animal swells and that the wool falls off. None of these symptoms are specific of Black Disease alone. They occur in more or less degree in the same organs and same tissues in all diseases which are created by "toxins." You will find the same thing when sheep of any size die of Pulpy Kidney.

Then again, in diseases like Anthrax, the post-mortem appearances of this does not show any fluid to any great extent in the peritoneal cavity or very much around the heart. The reason for this is that it is not a toxin; it is purely a bacterial disease affecting the blood. Just why Anthrax kills has never been discovered. There are many theories as to its killing power, but nobody has ever been able to determine definitely just why and how it kills, except that it fills the blood stream with bacilli.

Let us look at acute fluke. This creates an appearance almost identical with that of toxic absorption, and here again it is a type of toxic absorption of a protein, a nature foreign to the tissues of the sheep; that is to say, a protein that belongs to another type of animal will create a reaction in the tissues of the animal into which it is introduced, and when further doses are introduced into the host animal, symptoms arise known as "anaphylaxis" or shock. In cases of acute fluke, first of all one or two get in and set up a reaction in the tissues, then larger and more rapidly, numbers appear in the system, burrow their way through the intestines, get into the peritoneal cavity and the lungs, and this in turn causes death and inflammation of the tissues. The symptoms on post-mortem appearences produced by acute fluke are closely in sympathy with that produced by Black Disease or Pulpy Kidney. You have fluid in the peritoneal cavity, fluid around the heart, engorged vessels, etc., and that same type of congested appearance throughout the system. That is why I suggest that acute fluke disease is a type of toxic poisoning, and this is reflected in the fact that the post-mortem appearances in the animal are consistent with those produced by toxic diseases in general.

The differentiating feature between Black Disease and Acute Fluke is the presence of blood in the peritoneal cavity. This does not interfere with the idea or suggestion that toxic diseases and diseases created by conditions which in themselves create toxic absorption will produce a train of post-mortem appearances quite identical. The general appearances are similar, but imposed on these are usually some special appearances particularly dependent and characteristic of the specific disease. Other types of disease create anaemia. As soon as you see a sheep with a bottle jaw or soft, puffy swelling underneath the jaw, you know that this is produced by anaemia, but the causes of the anaemia may be many. If you are an inhabitant of areas where fluke are very prevalent, you will say that the sheep has fluke. If you were to transport that sheep where they had no fluke to where stomach and hair worm were prevalent, you would be told the cause was hair worms. The point I wish to convey is that the swelling under the jaw is not significant of the cause but simply a symptom of a certain set of conditions more or less related and associated with anaemia. The mucous membrane of the mouth becomes pale, together with a bottle neck and lack of condition. Animals run a short instance and they lie down. This is not significant of worms; it signifies anaemia and weakness. Worms may be, and usually are, the cause, but so might other conditions, and in finding the presence of a few worms in the animal you could not necessarily say that they were the cause and circumstances which killed the sheep. The real cause is anaemia. In West Australia there is a disease producing these symptoms and which is typical of anaemia, and similaily in New Zealand there is a disease which is purely anaemia and which shows the same set of symptoms and appearances on post-mortem, and in these areas there may be no worms at all in the stomach.

In anaemia the blood is very thin and watery; it has not got a good red colour and does not stain the tissues and appears to be a streaky light pink. The muscular tissue appears weak and the connective tissue is streaky and very white. The heart is limp and the colour of the muscle of the heart is pale. All of these appearances occur in severe worm infestation, but can occur without the presence of worms. However, in almost every case in New South Wales the possible condition is caused by worms.

You should not arrive at the conclusion that because you see anaemic sheep that they must have died of worms. I have seen sheep die without any worms but with chronic cirrhosis of the liver, being devitalised through repeated attacks of fluke, mostly occurring in ewes of seven or eight years of age who have lived in hilly country where they have been bred and raised and lived their lives. When you open them up the liver is completely covered with white streaks and often are without any fluke at all. This is cirrhosis of the liver. So that in general we obtain post-mortem appearances running in groups, and so we commence to differentiate our findings into lines such as these: poisons, toxins, bacteremias, cyanoses (such as Hoven, strangulation. H.C.N.) and by having determined the "group" we then look for the differentiating conditions to assist us in determining the exact disease such as the yellow patch on the liver in Black Disease, the black gassy muscle in Blackleg, and the blood in the peritoneal cavity in Acute Fuke, etc.

 


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