References to, and investigations relating to, the part played by the
bull in the process of reproduction in the herd, and in the spread of
genital infections, have been limited largely to those phenomena caused
by _Bact. abortum_. Bang (1) originally called attention to the
possibility of the male transmitting the organism discovered by him, but
he reached no definite conclusion on the subject. James Law (2) writing
on contagious abortion in cows, early suspected this possibility when
stating under “casual infections,” that—“In a case which came under the
observation of the writer recently, a family cow, kept in a barn where
no abortion had previously occurred, was taken for service to a bull in
a herd where abortion was prevailing, and though she was only present at
the latter place for a few minutes, she aborted in the sixth month.”
Jansen, as quoted by Sand, reports the case of a cow from an aborting
herd having been taken into a herd that had been previously quite free
from the disease. Soon after her arrival she aborted, and later cow
after cow of the original herd aborted. The owner kept the matter a
secret, and sent his cow to a neighbor’s bull for service, with the
result that for two years abortion prevailed among cows served by this
bull. McFadyean and Stockman (3) later, in experimental work, attempted
but failed to infect cows by using a soiled bull for service. Hadley and
Lothe (4) state: “A large number of stockmen hold that the bull is an
important factor in the transmission of contagious abortion in herds. A
smaller number believe that the bull merely acts as a passive carrier of
the abortion disease and is not actively concerned in the transmission.”
In a subsequent bulletin, Hadley (5) remarks: “The abortion organisms
may enter the body ... during sexual intercourse.” In an experiment
carried on by the same author and co-workers, abortion-free virgin
heifers were mated to abortion-infected bulls, infection being evidenced
by positive reactions to the complement fixation and agglutination
tests. His results indicate, he believes, “that the bull is not so
important a factor in transmitting abortion as many believe.” The
conclusions are: “Bulls may become infected with abortion bacilli. Bulls
that reacted to the blood tests were incapable of disseminating the
abortion disease to the abortion-free heifers with which they were
mated. Bulls appear to possess a sexual or individual immunity to
abortion infection that renders them less susceptible than cows and
induces a milder form of the disease. The resistance appears to be due
to certain anatomic and physiologic differences in their sexual organs
which make them less favorable places for the growth of the abortion
germs than those of the opposite sex.”
Buck, Creech, and Ladson (6) applied the agglutination test to 325
mature bulls, of which 288 were negative and 37 positive. _Bacillus
abortus_ was isolated from five animals, of which three showed marked
lesions, two in the seminal vesicles, and one in the left testicle. They
conclude: “_B. abortus_ may involve organs of the generative apparatus
of bulls, producing chronic inflammatory changes. Of the generative
organs, the seminal vesicles appear to furnish the most favorable site
for the lodgement and propagation of abortion infection.”
Schroeder and Cotton (7) cite the case of a bull which reacted to the
abortion test and, on post mortem, _Bact. abortum_ was isolated from an
abscess of one epididymis. They state: “Our attempts to produce a
similar case of infection artificially failed, and, in agreement with
the difficulties many investigators have had to obtain incriminating
evidence against bulls, we have thus far failed to infect bulls in any
way that justifies the assumption that they are important factors in the
dissemination of abortion disease.” Further, they conclude: “Regarding
the dissemination of abortion disease by bulls, we may say, however,
that it would be foolhardy in the dim light of our present knowledge to
take liberties with reacting bulls, or bulls from infected herds, or
promiscuously used bulls.”
Cotton (8) failed to demonstrate the presence of abortion bacilli in the
genital organs of the bull used to serve aborting cows, or in the
testicles of two bull calves, one of which had been fed and the other
injected with the cultures of the abortion bacillus. He concludes that
the bull does not harbor the organisms in the testicles. Carpenter (9)
injected both _streptococci_ and _Bact. abortum_ into the scrotal sacs
of young calves, and intravenously in others. In no case was he able to
recover the organisms from any part of the genital canal, except for a
_streptococcus_ in one instance. Rettger and White (10) were unable to
obtain evidence of the presence of _Bact. abortum_ in three bulls
slaughtered after repeated reactions to the complement fixation and
agglutination tests. The three bulls had been under observation for
three years, with no conclusive evidence to indicate that they were a
source of danger to the herds in which they were a part. They believe
that the bull transmits the infection as a passive carrier.
Attempts at artificial inoculation by natural channels have failed, with
the possible exception of McFadyean, Sheather, and Minett (11) who were
able to infect the bull by the prepuce in two cases and by the mouth in
one case. The results, however, are by no means conclusive. They
conclude, nevertheless, that cattle of any age of either sex may be
infected by natural channels with the bacillus of epizootic abortion.
Schroeder (12) carried out investigations to ascertain the frequency
with which bulls react to abortion tests, and the frequency with which
lesions chargeable to abortion bacilli occur in the reproductive organs
of reacting bulls. Studies were also pursued which he states
conclusively prove that bulls with infected reproductive organs may
expel abortion bacilli with the seminal fluid. In the first two
mentioned investigations 325 bulls from a Washington abattoir were
tested, and slaughtered upon reaction. “Approximately ten per cent of
the bulls reacted, and approximately ten per cent of the reacting bulls
showed lesions of the reproductive organs from which abortion bacilli
were isolated.” The value of these studies, he emphasizes, lies not in
“that they give us a measure of the proportion of bulls that react
positively to abortion tests or the proportion of reacting bulls that
are carriers of abortion bacilli,” but in “the fact that they show that
abortion bacillus disease of the bull’s reproductive organs is not a
wholly unique affection which practically may be ignored, but an
important condition that must be taken into account in our efforts to
combat infectious abortion, since it has been proved to be associated
with contamination of the seminal fluid.” In discussing the method by
which infected bulls transmit the organisms to cattle, he believes that
leakage of semen from the penis, or vaginas of cattle after service,
contaminates the food which subsequently gains entrance to their
digestive tracts. As the result of a series of experiments, he states:
“... the results fail to justify in the least degree the assumption that
cows are infected with abortion bacilli via their vaginas or uteruses at
the time of copulation, or that the bull, through copulation, is an
agent in the spread of abortion disease.”
The work so far alluded to, has been limited to infection with, and the
transmission of, _Bact. abortum_ and the lesions associated with such
infection. The last mentioned author, however, states: “A search for
other specific causes of abortions among cattle has not been neglected,
and bureau investigators could relate at great length stories similar to
those which investigators have told about microorganisms isolated from
the products of abortions and the uteruses of cows that have aborted.
Bacilli of various kinds, different types of micrococci, and spirilla or
vibrio have been found repeatedly; but when their pathogenicity has been
tested in accordance with widely recognized and accepted and required
bacteriological standards, not one shred of evidence has been obtained
to prove them true etiological factors of bovine abortions. What role
such microorganisms may have as causes of the sequellae of infectious
abortions, and of other, possibly, independent, abnormal processes in
the reproductive organs, is far from clear and merits careful study.”
Hadley (5) mentions the fact that: “Unquestionably the male often
becomes infected with the germs that produce the various secondary
diseases in the female, which are properly classed under the more
inclusive term ‘abortion disease.’” Also, speaking of the rarity with
which the bull acquires abortion infection, he alludes to the fact that
he may act as a “mechanical carrier of various disease germs from an
infected to a healthy cow.” Carpenter (9) working on the female genital
tract, comes to the conclusion that, in all probability, the genital
organs are normally free from bacteria. Barney (13) quoting Huet finds
that bacteria may be present in the seminal vesicles of healthy animals
(horses, cattle, pigs, and laboratory animals). This, he states,
corresponds with the well recognized findings in other parts of the
genito-urinary tract, not only in animals, but in man. He (Huet) has
further found that in animals dying of acute septicemia, the specific
organism (anthrax, pneumococcus) is to be found in the vesicular
secretions. Furthermore it was definitely shown that an infection could
be transmitted to the female during the act of copulation.
Williams, W. L. (14), calls attention to the lack of veterinary
literature relating to the pathology and bacteriology of the male
genital tract, except as related to infection with _Bact. abortum_.
Infection with other types of bacteria is emphasized, the clinical
recognition of such, with the accompanying pathological changes, and of
the numerous phenomena involved in the process of reproduction in the
male. The semen and its essential germinal elements are taken up with
reference to the entire lack of study devoted to them, and some of the
abnormal changes are described. In a later contribution (15), he takes
up the part played by the bull in the dissemination of genital
infections and states: “Clinical studies now indicate with great
clearness that the bull is an active spreader of that group of genital
infections which cause sterility, abortion, and related phenomena.”
Williams, W. W. (16), studied the semen with reference to sterility,
emphasizing the importance of its examination in the diagnosis, giving
methods for collecting samples, staining of sperms, and some of the
abnormalities encountered. The work is fundamental, and should be of
great practical importance to all interested in the problem. In a later
paper (17), he brings out a more extended discussion of the question. He
concludes that the clinical examination is of vital importance, and that
the efficiency of the semen depends not only upon its physical
properties but upon the number of spermatozoa that are motile, the
degree of motility, degree of obligospermia, and the percentage of
imperfect spermatozoa, either deformed or immature. Of forty bulls
examined, he finds that twenty, or fifty per cent, showed lessened
fertility, and others, aside from this, showed minor changes in the
genital organs or semen. The same author subsequently takes up the
subject of reproduction from the viewpoint of both sexes, but
emphasizing infection in the male, and the frequency with which lowered
vitality of the germinal cells occurs. Hopper (18) states: “A diseased
bull may manifest non-fertility or decreased potency in different
ways—by repeated service to apparently normal females without
conception, by a high abortion rate in females that have been apparently
normal, by characteristic infections following the use of any particular
sire, or by abnormalities in the breeding tract noted by rectal or
physical palpation.”
The observations of Williams (19) in a pure bred dairy herd bring out
quite clearly the relation of the bull to the dissemination of genital
infections. The bulls in this particular herd were abnormal in many
respects, as demonstrated by pathological changes in their genital
organs, bacterial invasion of the parts, abnormalities of the semen and
spermatozoa, and the probable transmission of infection to the females.
Several of the sires from this herd furnished much of the material for
the early basic work of this investigation. Since then the tracts of
other sires have been worked upon with quite similar or identical
results.
To summarize the work already done, most investigators have considered
the bull as merely a mechanical carrier of _Bact. abortum_ infection,
though all are more or less suspicious of his ability to become an
active spreader. Schroeder, however, states that the organisms are
eliminated with the semen, but infection of the female occurs
secondarily through the digestive tract by contamination of the food
with the semen. Other investigators bring out fundamental points
demonstrating the importance of other organisms than the Bang bacillus
and call attention to the need of a more thorough study of the anatomy,
physiology, and pathology of the male genital tract.
Any study of the genital organs must of necessity rest fundamentally
upon a thorough knowledge of the anatomy and physiology of those parts.
Too few of us have stopped to consider these questions thoroughly, with
the result that our ideas on the problem are more or less vague. It is
much easier to understand why abnormal spermatozoa occur so frequently,
or changes take place in the semen with death or weakening of the
germinal elements, if we realize or stop to consider the highly
differential process of spermatogenesis, and the various structures
which contribute to the formation of the semen. We must come to realize
that each part of the genital tract is essential to the normal
functioning of the whole, and that the genital tract and reproduction
are in turn dependent upon the proper functioning of the entire body.
Walker (20) emphasizes the importance of a thorough knowledge of
physiology in stating, “Although the subject of sterility has attracted
the attention of the medical profession; and although much has been
written on its causes and treatment, it cannot be claimed that the
practical results obtained up to the present time are satisfactory, or
that when consulted for sterility, the medical man of today can hold out
to his patient much more hope of successful treatment than the medical
man of fifty years ago. Our failure in this respect is in the main due
to an ignorance of the physiology of reproduction.”
To bring out some of these points, the anatomy of the tract will be
reviewed briefly, together with the physiology of reproduction, and the
various factors which should be considered in a study of the problem.