On the Significance of Bovine Tuberculosis and 
Its Eradication and Prevention in Canada* 
By 
J. GEORGE AD AMI, M.A., M.D., 
Professor of Pathology, McGill University, Montreal, and Pathologist to the 
Agricultural Department, Dominion of Canada. 
The Canadian Journal of Medicine and Surgery, 
Reprinted from 
December, 1899 ON THE SIGNIFICANCE OF BOVINE TUBERCULOSIS AND 
ITS ERADICATION AND PREVENTION IN CANADA.* 
J. GEORGE ADAMI, M.A., M.D., 
Professor of Pathology, McGill University, Montreal, and Pathologist to the Agricultural 
Department, Dominion of Canada. 
In determining the significance of bovine tuberculosis so as to 
arrive at adequate conclusions—adequate, that is, from all points of 
view—three main questions have to be asked and answered. 
These are: 
1. Is tuberculosis in cattle a source of danger to other cattle so 
as to seriously affect their well-being, and to be a source of loss to 
their owners ? 
2. If infectious from animal to animal, is it infectious from 
animal to man, and thereby a grave source of danger to the human 
race ? 
3. If infectious from animal to man, what are the commonest 
modes of infection, and, as a sequel to this, how are we to diminish 
the danger ? 
If even the first of these only can be answered in the affirma- 
tive, then it becomes necessary to inquire how the disease can be 
arrested, and it is for our profession, as interesting itself in disease 
in general, to take a leading part in agitating for this arrest. If 
both the first and second, then are we not only indirectly but 
directly affected, and to allow tuberculosis in cattle to gain a 
headway without ourselves employing all the means in our power 
to arrest its progress, is little less than criminal. 
To-day I propose briefly to consider in order, first, the signifi- 
cance of the disease, next its frequency in our country, and finally 
the steps necessary to stamp it out. 
1. Is tuberculosis in cattle a source of danger to other cattle ? 
To this the answer is an unqualified affirmative. We have abund- 
ant evidence here in Canada that the introduction of an infected 
bull, as again of infected cows, into a herd previously free from the 
disease, has been followed within a short time by symptoms of the 
disease in members of the old herd. 
* Being a paper read at the meeting of the Canadian Medical Association, Toronto, 
August 28th 1899. 2 
The ravages which this disease creates among the cattle of 
civilized communities is something appalling. Here in Canada, as 
I shall proceed to point out, we are in a relatively very favorable 
condition, and most of us in our profession see very little of the 
disease and of its results. It is otherwise in the Old World; there 
the steady spread of this plague among the dairy herds is creating 
widespread alarm. That it is extending there is no doubt. The 
following table of slaughter-house statistics, which I take from an 
article by Professor Conn, gives some idea of the rate of this 
spread: 
1877 1.62 per cent. 
Bavaria. 
1888 . . 2.7 
1895 5 
Saxony. 
1888 4.90 “ 
1890 15.7 “ 
1895 27.48 “ 
Berlin. 
1883 2.86 “ 
1885... 2.10 “ 
1895 15.45 “ 
1888 11.1 “ 
Leipzig. 
1889 14.9 “ 
1890 22 3 “ 
1891 26.7 “ 
1895 33.3 “ 
It may be objected that this increase is only apparent, that the 
veterinarians and the officials at the slaughter-houses have of late 
years learnt to recognize the disease with increasing accuracy, a 
single tuberculous gland being now often detected, whereas it was 
passed over in earlier years. It may also be objected'that other 
factors have to be taken into account, namely, the experience of the 
inspectors, the attitude of the inspectors towards the disease—a 
desire to find little resulting in little being found, and vice versa; 
that, further, the age of the animals slaughtered affects the results 
(tuberculosis being a disease showing itself especially in older 
cattle),* But all through the period indicated by the above table 
great attention has been paid to the subject by veterinarians; their 
eyes have been opened to the existence of the disease, and to 
methods of gross anatomical diagnosis in the carcase. At Leipzig 
more especially, as Conn points out, the inspection has been most 
* According to RoekI (I quote from a report of Dr. Bryce to the Provincial Board of 
Health, Toronto), from a consideration of some 51,000 animals slaughtered in German 
abbatoirs in 1888-89, according to the age of the animal the infection was found : 
6 weeks old 0.6 per cent. 
6 weeks to 1 year 0.6 “ 
Ito 3 years... 11.4 “ 
3to 6 years 33.1 “ 
Over 6 years 43.4 “ 3 
careful. It lias been under the same management during the whole 
period, so that the results of successive years may more safely be 
compared with each other than in most cases, and Leipzig affords 
the strongest evidence of the increasing frequency of the disease. 
This rise in percentage of tuberculous cattle seen in the slaughter- 
houses at Leipzig from 11.1 per cent, to 33.3 per cent, in seven 
years is veritably appalling, and no other explanation can be 
afforded than that the disease, in Germany at least, is spreading 
with terrible rapidity. So much indeed is this the case that 
competent authorities there are of opinion that in a few years there 
will be no breeding herds left unaffected. If, in place of the 
slaughter-house statistics, we take those afforded by the tuberculin 
test, the percentage of cases found in animals other than yearlings 
is yet higher than those afforded by the slaughter-houses. In 
Germany and Denmark veterinarians have come to the conclusion 
that the amount of tuberculosis is over 50 per cent, of all the 
animals in the land, many large farms being found without a single 
sound animal. In other words, about half the animals in northern 
and western Europe would seem to be afflicted with tuberculosis. 
Corresponding statistics for Britain do not exist, nevertheless 
the conditions there, it would seem, are scarcely if at all more 
favorable. Thus in the County of Midlothian, abbatoir statistics 
show the existence of the disease in 22 per cent, of the animals 
slaughtered, in Yorkshire a percentage of 22.8, Durham 18.7, and 
in London 25 per cent. These, be it remembered, are slaughter- 
house results and not those derived from the tuberculin test. In 
fact, tuberculosis among the most valuable and most highly bred 
herds is so extensive that extreme precautions should be taken and 
stringent contracts made by the buyer as well as stringent regula- 
tions framed and carried out by the Government to insure that, 
however great the cost of the individual cow or bull imported, the 
animal be found perfectly sound and unaffected by the disease 
before it is permitted to enter the country. 
Personally, though in this I speak in no official capacity, I am 
inclined to think that, taking into consideration the fact that if 
once an animal has been inoculated with tuberculin it may not give 
a second reaction until more than a month has elapsed, I would 
urge that all cattle imported for breeding purposes be kept in 
quarantine for six weeks at least, and only permitted to be 
delivered, to owners in this country if at the end of that period they 
fail to react. Otherwise, by any other course, there is a distinct 
danger that the disease may be introduced into herds previously 
quite free from the disease. 
Nor even in the Eastern and older populated States of America 
is the condition much more satisfactory. Certainly, in Massachusetts, 
where the most painstaking observations have been made, the dis- 
ease has been found very common. In their report for 1895, the 
Cattle Commissioners of that State show that in several large herds 
the percentage of animals reacting to tuberculin was as high as 4 
100 per cent. These are, it is true, extreme cases. Of 3,295 
animals examined by inspectors and others in various parts 
of the State, 810, or about 24.58 per cent, reacted. Of neat 
cattle examined at the Stock Yards, about 6.21 per cent, were 
condemned, while in the district of Nantucket, selected because 
of its position as an island on the coast upon which there 
were comparatively few cattle, and these fairly well isolated, 6 
of the 665 animals upon the island, or rather under I per cent, 
reacted to the test. This, while it shows considerable variation in 
the prevalence of the disease under varying conditions, shows also 
that it is far from infrequent, and that care must be taken with 
regard to importation of stock for breeding purposes, from the East- 
ern States as well as from across the sea. 
What are the results of and what the dangers from this extraor- 
dinary prevalence of the disease elsewhere ? 
First and foremost, there is the effect upon the animal itself, 
upon its value as a milker, a breeder, and a meat-giver. While 
for some months a cow reacting to the tuberculin test may remain 
sleek and give abundant milk, sooner or later the disease pro- 
gresses, she emaciates, dries up, becomes useless, and when killed is 
almost useless. What was once a valuable animal is finally a 
great loss to the farmer. I have met with cases of apparent healed 
or obsolescent tuberculosis in cattle, and it may be that such cases 
are not uncommon—in cattle, just as in man; but undoubtedly the 
danger is that the disease will extend. 
In the second place, though this matter I shall not discuss at 
the present moment, there is the danger to the community in 
employing the milk and meat from such an animal. In any case 
where this disease is at all frequent, the loss to the farming com- 
munity, and so to the country at large, is enormous. 
Even in Scotland, which cannot be called a large country, or 
one in which cattle-raising and cattle-breeding is the staple occu- 
pation of the inhabitants, Professor Wright, in 1893, estimated 
that tuberculosis in cattle caused an annual loss of dairy stock of 
about £440,000, or $2,000,000, and this apart, I take it, from con- 
siderations of loss in milk and butter, and loss as breeding animals. 
We may therefore conclude that, purely from the standpoint of 
the agriculturist, it is all-important that this disease be if possible 
eradicated. 
11. If infectious from animal to animal, is bovine tuberculosis 
infectiousfrom animal to man? The answer to this question is 
generally given as an unhesitating affirmative. I wish, however, 
to point out to you to-day that while we must accept the affirma- 
tive as the correct answer, and while it is the duty of the individual 
and of the State to act in full accordance with the belief that this is 
so, the amount of reliable evidence of direct transmission of tuber- 
culosis from cattle to man is singularly slight. For let us consider 
the means at our disposal for determining this point. Could we make a direct experiment the determination would be easy 
and straightforward; but this is just what we cannot do. To 
inoculate the human being with tuberculous material, or expose 
him to infection from a diseased cow, would be a criminal act; it 
would differ in no sense from attempted murder. We can, it is true, 
perform the opposite experiment, that of inoculating cattle with 
phthisical sputa or other tuberculous material from man. If we do 
this, as Theobald Smith has pointed out, we discover the remark- 
able fact that cattle are relatively insusceptible, or are but slightly 
susceptible to human tuberculosis. Whereas tubercle bacilli 
obtained from cattle introduced into other cattle induce a relatively 
virulent disease, those obtained from man either set up mild chronic 
disturbance tending to be localized or lead but to transient results, 
what tubercles are formed undergoing absorption and disappearance. 
Our own observations in Montreal fully confirm Theobald Smith’s 
statement. That, because for cattle bovine tubercle bacilli are very 
virulent, therefore they are also very virulent for man, more than 
are the human bacilli, we know from comparative bacteriology to 
be an absolutely unsound deduction. This may be so, but it 
may not. We have fairly abundant evidence that passage 
of pathogenetic germs through a series of animals of one species, 
leads to those germs attaining their maximum virulence for that 
species—but not by any means necessarily for other species. In- 
deed at times the virulence for other species is distinctly lessened 
by such passage, and in connection with tuberculosis we have dis- 
tinct evidence that the bacilli obtained from fowls suffering from 
tuberculosis differ even more widely in properties from those 
obtained from man than do the bovine tubercle bacilli. Despite 
some earlier observations to the contrary, it is now generally found 
that fowls may, with impunity, be fed with human phthisical sputa 
without becoming infected. Kruse has, it is true, obtained in a 
few cases tubercle bacilli of the avian type from the human body, 
indicating that man may be infected from birds. But we cannot 
legitimately and by analogy apply these observations to the case 
of bovine tuberculosis and man. We are forced, therefore, to fall 
back upon evidence of another type. 
Do the bacilli gained from the human and bovine species possess 
a morphological and cultural identity ? They do not. The bovine 
grow more freely in the ordinary glycerinated media; they are, I 
find, of greater relative breadth, while again, as already indicated, 
pathogenetically they exhibit different degrees of virulence, and 
this when inoculated not only into cattle, but into guinea-pigs and 
the small animals of the laboratory. Koch, it is true, in his classi- 
cal experiments held them to be identical, but later research has 
shown them to be so distinct as to make some observers consider 
them distinct species. But to classify them as distinct is to pass 
beyond what is right and reasonable. We are accumulating more 
and more facts to show that pathogenetic bacteria may undergo 
extensive modification according to the nature of their environ- 
ment, and that within certain limits bacteria may show more or 6 
less permanent variation of common properties as a result of varia- 
tion in environment. And in this matter of tuberculosis we have 
the most important observations by Nocard and Roux that avian 
tubercle bacilli, which differ more widely from the human than do 
bovine, can be shown not to be a distinct species, but what may be 
termed a race:— 
While under ordinary conditions, human tubercle bacilli inocu- 
lated into birds are destroyed, and lead to no organic changes, if a 
pure culture of such bacilli be placed in celloidin capsules, and those 
be then hermetically sealed and introduced into the abdominal 
cavities of birds, when thus protected from the body cells but fed 
by the body humors which diffuse through the celloidin, they will 
grow, and in the course of weeks assume all the characters and all 
the pathogenetic properties of the avian bacilli. We can only from 
this conclude that the races of the tubercle bacilli spring from a 
common stock, and have undergone material modifications accord- 
ing to their surroundings. So far, however, bacilli having all the 
morphological and cultural characteristics of the bovine “ race,” 
have not been isolated from the human organism, nor do I know 
that, so far, by placing protected human bacilli in the abdominal 
cavity of the cow, these have assumed the bovine characters. It is 
in this last experiment, I believe, that the solution of the question 
is to be found. For if we can show that under favorable condi- 
tions the human bacillus can become highly pathogenetic for cattle, 
the converse would also seem to hold that there are conditions 
under which bovine tubercle bacilli can be pathogenetic for man. 
Failing direct experimental and bacteriological evidence of the 
absolute identity of bovine and human tuberculosis, we are for an 
answer to this question driven back yet further, and this time to 
casuistic evidence. Have we any evidence or absolute proof that 
by natural means tuberculosis has been conveyed from cattle to 
man ? We generally teach that we have such positive proof, and 
at first thought it would seem easy to collect case after case in 
which, for example, butchers, and those dealing with tuberculous 
animals, have become infected through wounds, and so on; or 
again, of children and other human beings fed upon the infected 
milk of tuberculous cattle developing tuberculosis. But when we 
come to examine into these cases, we must be struck by the lack of 
indisputable evidence afforded. To prove the case we must be able to 
absolutely exclude every other possible mode of infection, and with 
human tuberculosis so common a disease, such exclusion is a matter 
of extreme difficulty. It must be shown that the individual has 
not come into contact with any other human being actively suffering 
from the disease. In the case of butchers it has to be proven that 
they have dealt with tuberculous cattle, and no other infected ani- 
mals : previous cases of human tuberculosis in the neighborhood 
have also to be excluded, for we know that in dwelling-houses the 
virus may linger for long in the dust and in hangings of rooms. 
Thus, to obtain an uncomplicated case is a matter of the greatest 
difficulty. 7 
Upon broad principles, it is true, the frequency of tuberculosis 
among children and its increasing frequency during the period 
when they have a diet largely of cow’s milk, would appear to be a 
strong argument in favor of believing that the milk of cows affords 
the most likely source of infection. Only in this last week’s 
British Medical Journal, in an able paper by G. F. Still of the 
Great Ormond Street Hospital for Children, the matter is brought 
forward very clearly. He considers a series of 769 consecutive 
necropsies on children under twelve years of age; in these no less 
than 269, or more than one-third of the total number of cases, 
showed tuberculous lesions. We find of these 269 cases, 117 or no 
less than 43 per cent, occurred at the milk-drinking period of life, 
namely during the first two years of life, and 56.5 per cent, 
occurred in the first three years. Undoubtedly the main incidence 
of tuberculosis in the young corresponds more or less exactly 
with the period in which milk forms, or should form, the chief 
article of diet, and as Still quotes from a report on tuberculosis, 
presented to the Council of the British Medical Association, “ the 
mortality from tuberculosis in early childhood is not decreasing as 
it is at other ages in the United Kingdom, and the opinion that 
this great prevalency of the disease in childhood is due to infection 
through the alimentary canal by milk from tuberculous cows, 
appears to be well founded.” ■ 
But now let us analyse Dr. Still’s very careful studies upon the 
sequence of infection. To determine such sequence is a difficult 
matter, because tuberculosis in children so rapidly tends to become 
generalized, and it is difficult to make out which are the oldest and 
which the more recent lesions. But a study of the lymphatic 
glands affords material aid; thus, large cheesy or caseous masses in 
a mesenteric gland with scattered tubercles in the peribronchial 
glands indicates that the intestinal lesion is the older, and conversely, 
if the peribronchial glands be the more affected, infection has been 
more probably through the respiratory tract. Tubercular adenitis 
of the larynx and tubercular ear disease would also appear to be 
mainly due to infection through the air rather than the food. Thus 
of the 269 cases above referred to the channels of infection were as 
follows : 
Respiratory ; 
Lung 
.. 1051 
\ 1S8J 
[ 153 = 57.2 per cent. 
[ 15 J 
Probably Lung 
Ear 
.. 33 j 
.. 91 
Probably Ear 
.. 6 
Alimentary : 
Intestine 
Probably Intestine . 
.. 531 
.. 10| 
j- 63 = 23.4 per cent. 
Other Cases : 
Bones or Joints .... 
.. 5 
Fauces 
.. 2 
Uncertain 
.. 46 
269 8 
It thus follows that respiratory rather than alimentary infection 
is the commoner in children in about the ratio of 57.2 to 23.4. 
While this is the case it must also be admitted that the proportion 
of cases of alimentary infection is relatively high, so high as to 
make it very probable that the staple food of children, namely, 
milk, does play a part in the spread of the disease. 
When now we come to examine the individual cases there are 
some which it is very difficult to explain unless we assume that 
infection has been through the milk. But while admitting this 
we have to confess that with scarce an exception the evidence 
afforded is not absolutely exclusive of possibility of infection by 
other means. 
Demme records a case of four infants in the Children’s Hospital 
at Berne, issue of sound parents, without any tuberculous ancestry, 
who died of intestinal and mesenteric tuberculosis as the result of 
feeding on the unsterilized milks of tuberculous cows. These were 
the cases in which he was able to exclude the possibility of other 
causes for the disease and was satisfied that the milk alone was to 
blame. 
The Cattle Commissioners of Massachusetts give reference to a 
case of an infant, son of a college mate of one of their body, a 
comparatively strong healthy child of twenty-one months, who, 
visiting a relation for a week, drank unsterilized milk of a cow 
which was soon after condemned and killed in a state of generalized 
tuberculosis; this child died three months later with mesenteric 
tuberculosis. Only distant relations had died of this disease and 
the child had seen but one of these and that for short intervals. A 
second child of the same family brought up on sterilized milk 
remained in robust health; the parents were free from the disease 
Even in a case like this, convincing as it seems, more information 
is required with regard to the nurse and servants of the household, 
the possible existence of any case of tuberculosis in the house of 
the relation visited, and so on. 
Ernst quotes similar cases. Olliver’s well-known case, quoted 
in the Semaine Medicate of February 25th, 1892, is also not quite 
perfect. The case was that of a girl of apparently healthy parent- 
age and previous surroundings, who died of meningeal tuberculosis. 
She was educated at a boarding school where thirteen pupils had 
been ill with, and then had died of, tuberculosis within a few 
months. The milk supplied to the school was from cows kept on 
the premises; these animals upon examination were found to have 
tubercular disease of the udders and to suffer from general tubercu- 
losis. Here, for example, it might be urged that under school 
conditions one girl might easily convey the disease to the other. 
The swiftness, however, with which the disease affected simul- 
taneously a large number of individuals, is on the whole, in favor 
of regarding the disease as having been brought about through the 
milk. Thus the evidence, while not absolutely convincing, is 
strongly in favor of the view that tuberculosis can be conveyed 9 
through the milk of animals extensively diseased, and this being 
the case, we cannot sit with hands folded and regard the extension 
of bovine tuberculosis with indifference, but must make such 
regulations as will diminish the possibility of such infection. 
’3. What are the more frequent modes of Infection ? Naturally 
apart from actual contact with the diseased animals and their 
products, the commonest modes of infection are by the animal 
products used as food, namely, the meat, milk and milk products. 
There are but a few words that I wish to say in this connection. 
The infectiousness of meat may be rapidly dismissed. Sims 
Woodhead and the British Royal Commission have shown that 
while the ordinary cooking of meat is sufficient to destroy tubercle 
bacilli, and while thus in English-speaking countries the danger of 
infection from this source is reduced to a minimum, it nevertheless 
may happen that the portion of a large joint in the centre may not 
be subjected to a temperature sufficient to kill the bacilli. At the 
same time the report from the same Royal Commission shows 
clearly that even in fairly well advanced cases of tuberculosis the 
bacilli are present but in small quantities in the meat itself; in fact, 
muscle is one of the last tissues to become the seat of the tubercular 
process. They show that the great danger is not from the existence 
of tubercles within the meat but of contamination of the surface in 
the process of dressing, by the knives and hands of the operators 
becoming smeared with material from other regions which are 
the seat of extensive disease. 
When such susceptible animals as guinea-pigs, fed directly with 
the expressed juice of raw meat, do not thereby become infected, it 
is, to say the least, little likely that cooked or even partially 
cooked meat can set up infection in man. Where the disease is 
so far advanced that the meat may become dangerous to humanity 
there is little likelihood of such meat being exposed for sale or 
employed as a food. 
With milk, the problem presents several difficulties. Accepting 
it as a fact that this can convey infection, the conditions under 
which it does so are, I think, not generally recognized. Thus the 
British Royal Commission lays it down that only when the udder 
is diseased does the milk become infectious, and would suggest that 
the withdrawal from the dairies of cows having any disease what- 
ever of the udder, would form some approach to security against 
the serious danger incurred to man by the use of tuberculous milk ; 
“ but it would not be an adequate security.” The report further 
states, “ if the expert finds tubercle bacilli in the milk, the cow has 
dangerous tuberculosis of the udder; if he does not find them, he 
may apply a further test by inoculating some susceptible animals 
with the milk and thereby learning the nature of the udder 
disease. By this test he will rarely be misled.” 
In this conclusion the British Commission strongly supported 
Nocard’s opinion upon this subject. But this view that the tubercle 10 
bacilli only pass into the milk when there is disease of the udder, 
I feel convinced is founded upon imperfect knowledge. This 
conviction is based upon the results of observations conducted by 
Dr. C. F. Martin and myself for the Dominion Government during 
the course of last year.* 
On ten cows placed at our disposal by the Minister of Agricul- 
ture necropsies were made, and we could not tind a trace of a single 
tubercular focus in any one of the udders, and that notwithstand- 
ing very careful study and examination. Any part that upon section 
looked to us the least suspicious, was subjected to examination 
under the microscope. Yet in the milk of two of these cows we 
detected bacilli in fair numbers, in four others on certain occasions 
we saw forms which we were compelled to describe as undoubted 
bacilli, and what is more, two of the guinea-pigs inoculated with 
milk from the cow which showed the greatest number of bacilli, 
undoubtedly succumbed to tuberculosis. It is true that the 
majority of the animals inoculated with this same milk remained 
perfectly free from the disease, i.e., of twenty-nine guinea-pigs 
and twenty-six rabbits inoculated intraperitoneally with varying 
quantities, only two guinea-pigs succumbed, while again a calf, fed 
solely with the milk from this cow, remained in perfect health 
although fed for five months. Had only this cow shown no sign 
of tuberculous disease of the udder we might have thought that 
our failure to recognize it was due to insufficient examination, 
but the same absence of udder disease was seen in the case of the 
other cows which afforded the bacilli. 
Since publishing our report Rabinovitch and Kempner have 
contributed to the Congress of Tuberculosis at Berlin a paper in 
which, by inoculation into guinea-pigs, they came to a similar con- 
clusion. Taking fifteen cows which had reacted to tuberculin, 
receiving the milk direct into sterilized glasses and inoculating 
guinea-pigs with a mixture of the precipitate and creamy layer 
after centrifugalization, they obtained the following results ; 
From ten of the animals (66.6 per cent.) they obtained a posi- 
tive result, but of those animals only one showed clinically definite 
tuberculosis of the udder, and one other showed udder tuberculosis 
under the microscope. Of the remaining eight cases three were 
found at necropsy to present advanced generalized tuberculosis 
without tuberculosis of the udder, one showed slight tuberculosis, and 
the remaining four only presented either dubious or absent clinical 
signs of the disease. They thus come to the conclusion that tubercle 
bacilli can pass into the milk even in the early stage of tubercu- 
losis in which there is no recognizable disease of the udder as also 
in cases in which the disease can only be detected by the 
tuberculin reaction. 
It has been objected in results of this nature that the bacilli in 
these cases are not truly tubercle bacilli, but are contaminations of 
* Report of the Minister of Agriculture of the Dominion for the year 1898. Ottawa, 1899. 11 
a relatively non-pathogenetic form. Thus, as has been pointed out 
recently, there may be present in milk a bacillus which micro- 
scopically is undistinguishable from the true tubercle bacillus, and 
which, when inoculated into guinea-pigs, produces a disease and fre- 
quently death with symptoms very similar to those of true tuber- 
culosis. But to animals other than guinea-pigs, this bacillus is not 
harmful, and probably it has no effect on man. Only by fuller 
experimentation is it possible to distinguish between these two 
forms of organism, and it is urged that, recognizing the presence 
of this false bacillus in milk and butter, experiments such as those 
above described are open to serious question. Indeed, some go so 
far as to claim that nearly all the fatal results obtained from inocu- 
lating butter into guinea-pigs, have been due to this false bacillus 
and not to the true one. 
Such a bacillus has been isolated from ordinary Timothy grass, 
and undoubtedly resembles very closely the tubercle bacillus, but 
herein comes the difficulty in accepting this explanation for our 
experiments and those of Eabinovitch. In our case the udders 
were carefully washed with creolin before milking, and whereas 
the milk was first passed through a sterilized funnel into sterilized 
bottles which we brought immediately to the laboratory, later the 
milk was received direct from the cleansed udder into the sterilized 
bottles. There was here practically no chance for contamination 
of the milk, unless indeed it be held that this false tubercle bacillus 
is a normal inhabitant of the larger milk ducts. Rabinovitch and 
Kempner took similar precautions. It is also interesting to note, 
in the second place, that we found a relationship between the num- 
ber of bacilli present in the milk and the extent of the tuberculous 
process in the animals. The two animals in whose milk we found 
the bacilli most extensively present were those showing most 
extensive disease of the lungs. Such a relationship would be impos- 
sible were we dealing with contamination. Thus I can only fall 
back upon the belief, that just as I have recently shown that the 
gland cells of the liver and of the kidney take up and discharge the 
colon bacilli, so the cells of the actively working milk gland in cattle 
have a similar power; and just as I find that the colon bacilli tend 
to be attenuated in their passage, so would I ascribe the somewhat 
altered appearance of these tubercle bacilli in milk of animals 
not suffering from udder tuberculosis to direct action upon them 
in the process of excretion, and would recognize that their lowered 
infective powers are due to the same result. At the present moment 
at the Experimental Station at Outremont, Dr. Higgins and I are 
putting this view to the test. 
For myself, therefore, I cannot but come to the somewhat 
unsatisfactory conclusion, that whereas, in the first place, the milk 
of animals not suffering from udder tuberculosis may contain bacilli, 
nevertheless such milk is not of high infective power, and that, 
therefore, the frequency with which the bacteriologist may by 
inoculation into the very susceptible guinea-pig find the milk to 12 
be infectious, it is not absolute indication of its danger when 
employed as a food for man. Only when there is recognizable 
udder tuberculosis and active tubercle bacilli are discharged into 
the milk in enormous numbers in consequence of ulcerative changes 
occurring in the tubercles, is there real danger. For practical 
purposes, therefore, I agree with Nocard, that as regards the milk- 
supply local tuberculosis of the udder is what has to be most espe- 
cially guarded against, and this, not because the evidence at our 
disposal affords absolute proof of the transmission of tuberculosis 
from cattle to man, but because the trend of the evidence is all in 
that direction. 
On the Extent of Tuberculosis in Canadian Cattle. 
So far as I can see there is no large tract of country in the 
North Temperate Zone in which cattle are so free from tubercu- 
losis as are our Canadian cattle, unless it be the Western States. 
During 1898 the testing of cattle was encouraged to the utmost 
possible degree by the Government, and as is natural, the applica- 
tions for inspection came more especially from those districts in one 
or other part of the Dominion where they had reason to fear the 
existence of the disease. In these “suspect” districts and “suspect” 
herds over ten thousand head of cattle were inoculated, and of 
these only 5 per cent, reacted. Further, of ninety thousand cattle 
inspected at Montreal during 1894 on the eve of debarkation, at a 
time when, in consequence of the active measures taken by the 
British Government against importation of Canadian cattle on 
account of suspected pleuro-pneumonia—a disease which I may 
add is absolutely non-existent here—at a period, that is, when great 
care was being taken not to export animals showing any infectious 
disease, only eighty animals were rejected by the inspectors, and of 
these eighty two were recognized as suffering from tuberculosis 
and even in them this was local. I do not mention these last figures 
as giving an absolute indication of the incidence of tuberculosis in 
Canadian cattle, but this I do say, that no other civilised country 
could now-a-days ship ninety thousand cattle under like conditions 
and have only two of the number rejected for clinically recognis- 
able tuberculosis. 
Similarly that same year the lungs of 2,504 animals were 
examined in the abbatoirs of Montreal, St. John, N. 8., and Halifax, 
N.S., and among these there were only fourteen cases of tubercu- 
losis or a percentage of 0.6. There is, I say, no other country which 
can show such low figures. One reason for this is that for now 
some years great care has been exercised in insuring that animals 
imported for breeding purposes are absolutely healthy. Another is 
that the keeping of animals within town limits, cooped up in dairies, 
is almost unknown, and yet another reason is that our animals in 
general have abundant pasturage and roam over wide areas; 
during the greater part of the year they live in most healthful 
conditions. 13 
Were any other indication needed with regard to the rarity of 
tuberculosis in our cattle, it is to he found in the following fact. 
For purposes of investigation of the Experimental Farm at Outre- 
mont, in order that Dr. Higgins and I could compare the infectious- 
ness of milk from animals with advanced disease of the udder, as 
compared with that from diseased animals not showing such udder 
trouble, it is absolutely necessary that we should obtain one or two 
cows showing udder disease. This most important portion of our 
investigations is at a standstill, merely because we cannot obtain 
such animals. We have only heard of one small collection of cases, 
which we could not utilize, as a matter of principle, because the 
owner, hearing that they were necessary to us, immediately 
demanded a ridiculous price. But Dr. McEachran, the Chief Inspec- 
tor, with the authority of the Minister, has sent detailed orders to 
all the inspectors over a large area of country, asking them to look 
out for and report any such advanced cases. That was some months 
ago, and still we are waiting to obtain these cattle. 
Prevention of Tuberculosis. 
The rareness of tuberculosis among our cattle makes it possible 
to hope for a complete eradication of the disease. In the Old World, 
where the disease is so common, such eradication appears chimerical 
—not only so, but is absolutely impracticable ; and there to begin a 
crusade of extermination and to slaughter every animal giving the 
tuberculin reaction would ruin the farmers—and would also ruin the 
Governments. To slaughter only animals showing clinical symp- 
toms would be but a sop in the pan; it would certainly not extinguish 
the danger of contagion and the slow spread of the disease. To 
restrict the movements of animals reacting to tuberculin would mean 
placing the whole country under the ban, and would absolutely 
paralyse the cattle industry.; while again, to compensate the 
farmers for the condemned animals would be found the cause of 
great dissatisfaction. The disease is so lingering and the eventual 
emaciation so marked that it is very difficult to arrive at any con- 
clusion as to what was the original value of the animal. The most 
that can be done there is to introduce what is known as Bang’s 
system, namely, that of separating the healthy from the diseased 
animals in separate byres, keeping them apart, and gradually, as 
the diseased animals die off, replacing them in the sound herd by 
animals which do not react, and also by adding to this sound herd 
the calves born to the diseased stock, it having been found that 
such calves, removed immediately from their mothers, show almost 
without exception no sign and no tendency towards the disease. 
Now, on the other hand, returning to Canada, the disease is so 
rare that Dr. McEachran calculates that probably throughout the 
Dominion but 10,000 animals show clinical symptoms, and this is 
probably an excessive estimate. Were there 10,000, and were these 
to be slaughtered, even at full value compensation would not exceed 
$250,000. Those reacting to tuberculin would be, of course, more 14 
numerous, but of these 70 per cent, at least, if not a much 
higher percentage, could be fed and slaughtered for beef under 
supervision, while in the case of highly bred cattle reacting to 
tuberculin, in which no clinical symptoms are discoverable, they 
could be kept in isolated buildings and treated and bred from under 
Bang’s system. 
1 cannot but cordially endorse Professor McEachran’s opinion 
that by the expenditure of an amount of money, trifling in itself, 
as compared with the enormous benefits that would accrue both to 
the live stock industry and to the people of Canada, the disease 
could be practically eradicated in the course of three or four years. 
Leaving out of account the hygienic importance of such eradica- 
tion, “ 45 per cent, of the population of Canada is engaged in rural 
pursuits ; the railways depend upon agriculture for one-fourth of 
the freight they carry, and the canals one-third. As regards the 
shipping industry, more than half of the total exports are agricul- 
tural products, the value of which for 1897 amounted, according to 
the Year Book, to the sum of $44,533,592. . . Surely no reasonable 
expenditure,” to quote Dr. McEachran, “ can be withheld to eradicate 
a disease that interferes with the development of an industry of 
such importance to the country’s prosperity.” And when, in addi- 
tion to this, we regard also possible danger to the health of 
humanity, surely it is our duty, as medical men, to support strongly 
any attempt on the part of the Government to bring about the pre- 
vention of this disease in cattle. 
I am most anxious that it be understood that I speak as a private- 
individual, but at the same time as one who has for the last two 
years continually studied the subject in its various aspects. If it 
seems overbold and too large a project to introduce this attempt to 
eradicate the disease simultaneously over the whole Dominion, at 
least, it seems to me, that the endeavor might he started in well- 
defined areas, Prince Edward Island, for example, Cape Breton, 
or Nova Scotia. And if what I have stated be correct—and our 
observations in Montreal entirely confirm those of Professor Theo- 
bald Smith—if cattle show but a transient and slight, and not an 
ulcerous and infective disturbance when inoculated with what are 
truly enormous numbers of tubercle bacilli obtained from man; if 
cattle thus are relatively insusceptible to the human disease; then 
the disease may be either eradicated or kept absolutely in check 
even although tuberculosis continue to prevail among the inhabi- 
tants of the districts mentioned, without adequate endeavors to 
arrest its spread among them. 
A corps of inspectors might be empowered to make a complete and 
perfect visitation, to kill off and compensate for all animals showing 
clinical evidence of the disease; to isolate or buy at full value, and 
place on Government reserves all animals reacting to tuberculin, 
according to the condition of their owners and their capacity or 
incapacity to undertake this work for themselves; to disinfect all 
byres in which infected animals have been discovered ; to prevent 15 
temporarily the entrance of animals into the areas visited after 
undergoing tuberculin test, and thereby to demonstrate whether 
these areas can be rendered absolutely exempt from bovine tuber- 
culosis. 
I believe that this can be done, and done at a cost relatively so 
small as to be incommensurate with the accruing benefit. For if we 
in Canada can establish herds absolutely free from the disease, this 
means that in a very few years Canada will become the great centre 
for the breeding of high-class cattle, and European countries will 
have to come to us to re-establish their herds. They cannot do it at 
home. We only, and only we, are in a position to make a fruitful 
endeavor to get rid of the disease in the course of three or four 
years. Possibly this statement is too sweeping, for there is a similar 
relative freedom from tuberculosis in the Western States, and by 
strict quarantine and rigorous inspection and regulations preventive 
of the entrance of untested animals, certain of those States might 
free themselves from this disease at a relatively small cost. But 
none of the States has the same favorable geographical position 
for testing the matter as we possess in our large islands and penin- 
sulas—Prince Edward Island, Cape Breton and Nova Scotia. The 
absence of natural boundaries must necessitate extreme care in the 
individual States as at any time the disease might reassert itself. 
In any case it is for Canada to make the endeavor.