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EDITORIAL ARTICLE. 33
(I). The infectivity of milk and its products, provided the contamination of these by means of the f;:eces and excreta of tuberculous animals has been excluded, is mainly referable to tuberculosis of the udder. Cows not affected with udder tuberculosis do not excrete tubercle bacilli, or at least not to any considerable extent.
(2). The transmission of tuberculosis is effected, in the first place, through the milk of cows with udder tuberculosis. In addition, the milk of clinically tuberculous animals, and of those in which the disease has reached an advanced stage, although the udder is not involved, are capable of causing infection; and this in no slight degree may be ascribed to a contamination of the milk with f;:eces and excreta. Contrary to what is the case with milk from tuberculous cows whose udders are not affected, the infectivity of which is nearly entirely abolished by dilution (as in ordinary mixed milk), the milk of cows affected with udder tuberculosis retains its pathogenic power after even the strongest dilution, and this warrants the conclusion that cows with udder tuberculosis are solely responsible for infection by means of such dairy products as butter, cheese, and butter-milk.
(3). Infection by milk and dairy products is particularly frequent in districts with a large dairy industry, especially in calves and pigs. In pigs it often leads in a short time to a 'progressive tuberculosis, and, since experience indicates that there are practically no other sources of infection for these animals, it acquires a great importance. Even in the case of calves and adult cattle the danger of the transmission of tuberculosis through milk and dairy products cannot be declared slight, although here it does not occupy a place of the first importance, as it does in the case of pigs.
(4). There is also a danger of the transmission of tuberculosis through milk and dairy products (butter, butter-milk, etc.,) to human beings, but at the present time it is impossible to say what is the extent of this danger.
(5). To avert the danger it is necessary to eliminate all cows with udder tuberculosis and all otherwise clinically tuberculous cattle, and to observe the greatest care and cleanliness in order to prevent contamination of the milk with the discharges of tuberculous animals. As a further precaution, milk and dairy products, before they are issued from the creameries, ought to be heated to 85 0 C.
E D ITO R I A L ART I C L E.
SEWAGE POLLUTION OF DRINKING WATER AS A CAUSE OF DISEASE IN ANIMALS.
A T a later part of this number there will be found the bulk of the evidence offered for the plaintiff and the defendants in an action which was recently tried in one of the Sheriff Courts in Scotland. It is possible that some of those who read it may be inclined to think
34 EDITORL\L ARTICLE.
that only a dearth of material suitable for publication, and not the intrinsic importance of the case, can have induced us to give so much space to it. In truth, however, the case is one of no little interest from a strictly professional point of view, since it brought to light the most remarkable differences of opinion with regard to certain important pathological questions among men who occupy prominent positions in the veterinary world. We therefore think it unnecessary to offer any apology for the amount of space we have devoted to the evidence, or for here discussing the validity of the opinions expressed by some of the profe'3sional witnesses.
The action was tried, in the first instance, before the Sheriff-Substitute in Ayr, and the decision was given in favour of the plaintiff, who was awarded £200 damages and expenses. Against this the defendants appealed to the Sheriff-Principal, but the appeal was dismissed with additional expenses. The facts of the case, by which we mean the circumstances that were admitted by both sides, were briefly as follows. The plailltiff, or, in Scottish legal phraseology, the pursuer, is the tenant of a farm on which is kept a dairy of from thirty to thirty-five cows. Throughout 1903 the health and general condition of the cows gave no cause for complaint, but during the following year they began to fall off in condition, exhibited symptoms of general unthriftiness, and yielded a smaller quantity of milk than they ought to have done. The cows had been put to grass about the middle of May, and their condition first became unsatisfactory about the end of July. Early in September one of the cows aborted, and six others cast their calves between that date and the 7th October. On the 19th November another cow aborted, but the seventeen remaining pregnant cows carried their calves to full term, while five proved to be barren. The cows which aborted had a good deal of discharge afterwards, suffered more or less in their general health, and failed to come into milk. During the summer of 1904, prior to the occurrence of the cases of abortion, the cows drank from a burn which had its source in the Heart Loch, a sheet of water about an acre or an acre and a half in extent, and varying in depth from three to five feet. The Town Council of Maybole, who were the defendants in the action, used this loch as a place of deposit for rubbish collected by carts from the town of Maybole, which has a population of about 6000 inhabitants. About the 18th October the cows were removed to another pasture with a different water supply, and the only cow that aborted after that was the one which slipped her calf on the 19th November.
A.pparently these are the only circumstances in connection with the case which were not disputed. Regarding everything else, whether a so-called fact or an interpretation of a fact, the evidence for the two sides revealed the most conflicting opinions. This applied to the extent to which the health of the cows had suffered, and to the degree
EDITORIAL ARTICLE. 35
of pollution of the water which they drank, but the most important difference of opinion touched the cause of the cases of abortion. The contention of the pursuer was that the whole of the mischief was attributable to the town refuse which had been deposited in the Heart Loch; while the case for the defenders was that the farmer had been the victim of an outbreak of contagious abortion, to which, directly or indirectly, all the depreciation of the health of the cows could be traced. It is with regard to this point only that we wish to examine the evidence of the principal professional witnesses for the pursuer.
Turning, in the first place, to the evidence given by Professor Wil!iams, it will be noticed that this witness expressed the opinion that water containing a large quantity of animal or vegetable matter is dangerous to pregnant .cows. He told the Court that if the organisms which cause decomposition" get into the animal economy they cause what is commonly known as blood poisoning. In addition the organisms secrete a poisonous fluid which is called toxine, and the drinking of water containing toxine gives rise to what is called toxine intoxication or sepsine intoxication. Both of these cause such a serious depression in the animal's economy that in many cases the animal gets what is commonly called typhoid or low fever; and as a result of this low fever pregnant animals are almost certain to abort and other animals to become seriously ill." Apparently in order to impress the court with the deadly character of impure drinking water, the witness stated that a few days previously he had inoculated a guinea-pig with a very small quantity of sewage water, with the result that it was dead next day. He had no doubt whatever that the injury to the cattle was caused through their drinking contaminated water. He did not believe that the cows had been affected with contagious abortion, which was" such a contagious disease that it spreads through a whole herd without exception."
Professor M'CaIl's evidence shows that he shares Professor Williams' views with regard to impure water as a cause of abortion. He thought that" if a pregnant cow drinks this impure water it would injure her blood, and through her blood vessels it would injure the fcetus. Her blood would be injured through indigestion." He also had no doubt that the abortion and illness of the cows had been caused by their water supply. He thought that the cows had been the subjects of septic poisoning, and that t!J.e state of affairs could not be traced to contagious abortion. He had previously had cases of abortion in cattle arising from drinking contaminated water.
The evidence given by these two witnesses appears to have greatly impressed the Sheriff, and there can be little doubt that it was mainly instrumental in securing the decision in favour of the plaintiff. Nevertheless, we do not hesitate to say that the opinions held by these two gentlemen regarding the r6le of contaminated water as a cause of
abortion among cows are absolutely devoid of scientific support. There is no really trustworthy evidence to show that impure water, or water highly contaminated with sewage, is capable of causing abortion, or that it is in any way injurious to cattle or other animals by reason of the organic matters, bacteria, or bacterial products present in it. The contrary opinion appears to be a survival from the dark ages of pathology, and it has not yet become extinct, partly because of the loose and inaccurate notions which are still current with regard to the pathogenic powers of the common putrefactive bacteria, and partly because it has unjustifiably been assumed that since sewagecontaminated drinking water is dangerous for human beings it must also be dangerous for farm animals. TakIng the last of these points first, it may be pointed out that in this country the only human bacterial disease which deserves to be called "sewage-borne" is typhoid, to which cattle and other domesticated animals are not susceptible. Besides, the bacillus of human typhoid has no claim to be called a putrefactive microbe, and its occasional presence in sewage-polluted water is solely attributable to the circumstance that where it is possible for human excrement to gain access to water there is always a chance that some typhoid patient may contribute to the pollution. There is not the least reason to suppose that sewage or any other form of impure water can ever become capable of infecting human beings with typhoid without the dejecta of a typhoid patient having been added to it.
N ow, it is no doubt possible that in precisely the same way drinking water, even although it were not charged with decomposing organic matter, might serve to distribute the germs of animal diseases. It might, for instance, carry the infection of contagious abortion. But that would be a very different thing from the role which, according to Professors Williams and M'Call, impure water plays in causing disease among cattle. It was not alleged that there was any disease in Maybole, either among the human beings or the animals there, which was likely t6 be conveyed, through the medium of the refuse deposited in the Heart Loch, to the cattle o(the plaintiff. On the contrary, it was implied that any material which is undergoing putrefactive decomposition is dangerous. Indeed, Professor Williams explained that it was doubly dangerous, for putrefactive bacteria when they gain access to what he calls the animal economy, meaning, no doubt, the alimentary canal, cause blood poisoning, while their products or toxines when taken in with drinking water are likely to induce septic intoxication. And the Sheriff appears to have been actually induced to believe that the entire water of the Heart Loch was charged to a dangerous degree with these deadily bacterial products!
It is unfortunate that Professor Williams was not asked where the pathogenic bacteria which infected or poisoned the cows belonging to the plaintiff came from, and that he was not reminded that the ali-
EDITORIAL ARTICLE. 37
mentary canal of cattle and all other animals normally contains hosts of putrefactive organisms capable of killing guinea-pigs by inoculation. The theory which he and Professor MCCall put forward implies that animal or vegetable matters undergoing decomposition in water either generate harmful microbes de 'NOVO, or endow harmless bacteria with pathogenic powers. At the present day the first of these suppositions cannot be seriously advanced by any educated person, and' the second is almost equally discredited. It is possible that unknown circumstances in the outer world occasionally intensify the virulence of bacteria, but there is no evidence whatever that putrefactive processes have any special tendency to act in this way. Not only is there no proof that the common putrefactive bacteria are dangerous "when they get into the animal economy," but it is easy to show that the opposite must be the case. Even under the utmost refinements of hygiene human beings cannot avert the entrance of putrefactive bacteria into their bodies, and a considerable variety of these are not only admitted every day but mUltiply to a large extent in the alimentary canal without entailing any harm. To a still greater extent this is true of cattle and the lower animals in general, for the simple reason that either in a state of nature or under domestication they are compelled to ingest immense numbers of putrefactive bacteria with their food and water. The continuance of the bovine species under the conditions of ordinary farming is proof positive that the common putrefactive bacteria are not pathogenic for cattle when taken in by the mouth. As to Professor Williams' guinea-pig experiment, we need say nothing except that, while it could not have been intended utterly to mislead the court, it was bound to have that effect if any attention was paid to it.
The harmlessness of the common putrefactive bacteria for animals when taken in by the mouth involves the innocuity of sewage in similar circumstances, but it may nevertheless be worth while to consider separately the question of sewage poisoning of cat.tle and other farm animals. In the first place, it may be asked, What is sewage? As ordinarily employed, the word refers to water carrying human excrement, and it is in that sense that sewage has on many occasions been accused by veterinary surgeons of causing more or less vague diseases among animals. Here again there is no scientific evidence in support of the opinion, and there is a large body of evidence against it. It is, of course, generally admitted that human excrement may contain the eggs of tapeworms and such specific bacteria as tubercle bacilli, and that sewage might be the means of introducing these pathogenic agents into the bodies of susceptible animals. But that is not what is meant by sewage poisoning when cattle are alleged to be the victims of it. Those who believe in its occurrence never seem to be able to give a clear account either of the symptoms or the lesions. The description given by Professors Williams and MCCall
is fairly typical-diarrhcea, loss of condition, typhoid or low fever, and abortion in pregnant animals. But all these, with the exception of this so-called "typhoid or low fever," are common enough among animals that have not drunk water contaminated with human sewage, and, what is equally to the point, they are not' more common among cattle kept on sewage farms. The truth appears to me that this belief in the evil effects of sewage-contaminated water on cattle and other domesticated animals has arisen from a slo\'enly habit of investigation on the part of those who have been called in to discover the cause of such symptoms as those previously mentioned. The man who approaches the question with the conviction that human sewage is capable of causing such symptoms is likely in many cases to find what he regards as conclusive evidence; on inquiry he discovers that the diseased animals have had access to water which is not pure according to. the chemical standard, or is known to receive a certain amount of sewage, and the whole matter is then supposed to be settled. But that is not the sort of evidence that will place this theory of sewage poisoning of animals on a scientific footing. Laymen may be ready enough to accept the general statement that the polluted water has caused blood poisoning in the animals that drank it: but pathologists will want to be told what were the characters of the bacteria that thus invaded the blood, and they will also require satisfactory evidence that they were derived from the sewage and experimentally capable of producing the evil effects attributed to them.
What has just been said applies to water contaminated with human sewage, and we have next to examine the alleged role of what may be called animal sewage in causing disease. That, however, calls for little consideration after what we have said regarding the importance assigned to putrefactive bacteria as a cause of disease among animals. I t seems passing strange that intelligent men should seriously endeavour to account for such diseased conditions as abortion, diarrhrea, and fever, whether low or high, on the view that the f<ecal bacteria of cattle are pathogenic to animals of the same species. To show the absurdity of such an opinion one only requires to ask those who uphold it to explain the harmlessness of farmyard manure as applied to grazing land, or to call attention to the thousands of wateringplaces in which cattle with impunity drink a liquid thick with their own excreta.
\Ve are not sure that Professors Williams and M'Call wiII thank us for having given publicity to their evidence in a professional journal. Much of it was of the kind likely to carry conviction to the lay mind, but, -as we have already said, their principal contentions with regard to the role of putrefactive bacteria in the causation of abortion and other diseases of cattle are behind the times and devoid of scientific support.
We have submitted their opinions to a reasoned refutation, not because we expect them to recant, but in the hope that the younger generation of veterinary surgeons will avoid the habits of careless observation, loose reasoning, and hasty generalisation of which these erroneous opinions are the product.
Itvitw.s. Surgical Diseases of the Dog and Cat and Amesthetics. By Frederick T.
Hobday, F.R.C.V.S., F.R.S.E. Second Edition. Revised and enlarged. London: Bailliere, Tindall, and Cox, 1906.
THAT the, first edition of this book was extensively used and widely appreciated is certain, and the great improvements in the present edition should ensure for it an even greater measure of success, The addition of symptoms and means of diagnosis, together with suggestions for general treatment, although not intended to be too exhaustive, is likely to prove useful; and the great number of good illustrations will serve to make clear and emphasise the text. The author has done much for canine surgery in the past, and this latest work of his should make the application of improved methods both in surgery and amesthetisation much more general, to the advantage both of the practitioner and his patients.
Whilst appreciating the general excellence of the work, there are several errors which should be avoided in a book for students, where exactness and accuracy in the use of terms are so necessary. Contrary to what is stated (p. 26), cocaine and eucaine (probably f3 eucaine) do not possess the same formula, nor have they the same constitution. Again" ranula" is due to an obstruction of a sublingual salivary duct or follicle. "Septicremia" should be reserved for cases where there are numerous organisms present in the blood, and not used for septic intoxication due to absorption of toxins (pp. 316-31;). Again, in a " compound" fracture the ends of the broken bone are not necessarily in communication with the air (p. 332), they may be completely cut off from the air by deep fascia. The advice to puncture the bladder in the linea alba, behind the brim of the pelvis (p. 245) may well puzzle a student. Salt solution injected to promote recovery after chloroform anresthesia is not likely to benefit unless the animal has lest a good deal of blood, and why a 5 per cent. solution? Surely normal physiological saline (about '9 to I per cent.) solution is best. Then, in using adrenalin as an intra-thoracic injection after tapping the chest (p. ISS), there does not appear any reason to suppose its action is different from that seen after its intravenous injection, viz., quickening of the heart'S action, ard great constriction of all vessels under the control of the vaso-motor nerves, and these actions are only of very short duration. In describing the chir f symptoms of choking, salivation and the dribbling of saliva from the mouth ought to be mentioned. The advice to puncture the stomach" on the ri;;1tt side, about an inch behind the last rib," does not very clearly define the position even when the word lift is inserted in place of riglzt.
There are a few obvious printers' errors, such as "muscular" for "vascular" (p. 165) under treatment of tumours; the reference" see p. 106" (p. ISO)