NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
THE DIAGNOSIS AND TREATMENT OF STERILITY IN THE
STALLION AND THE BULL
(A Resumé of the literature).
BY
CAPTAIN S. C. A. DATTA, B.Sc., M.R.C.V.S. ,
Temporary Veterinary Research Officer, Imperial Institute of Veterinary Research,
Muktesar.
[Received for publication on the 14th July, 1932.]
Of the many problems of importance that the animal clinician has to grapple
with, the determination of the cause of cessation of reproduction or reduced fertility
in the living animal is one of the most perplexing. Variability in the fertility of the
best known thorough-bred stallions and pedigree bulls or their absolute sterility has
inflicted a considerable loss to the breeding industry, but the majority of the
pioneers in this field, notable among whom have been Zschokke, Hess, Albrechtsen,
Wester, Williams, Richter and Quinlan [1929], have occupied themselves almost
exclusively with aspects of sterility in the female animal, and facts about the rôle
played by the male are less familiar. With regard to unproductive marriages in
man, that the male is as important as the woman has only recently come to be
recognised. At the present time, increasing demands for scientific veterinary
knowledge for help against sterility are being made and the problem is also increas-
ing in its scope due to certain recent developments in endocrinology. For the
reasons stated above and because the published literature on sterility in the male
animal is in an unsatisfactory state, the present article has been prepared. It will
be realised that further research and enquiry are urgently required for the elucida-
tion of this problem and it is hoped that this resumé, without any pretension to
being an elaborate or complete one, may lead to this end amongst workers in this
country.
Practical breeders have observed from olden times that all male animals are
not equally effective in impregnating their females and begetting healthy offspring.
Some animals are nearly perfect in this respect while others may require numerous
repetitions in service, even when mated with healthy females, and may even then
produce weak offspring, abortions or retained membranes wherever they are
employed. Sterility in the male may be due to a variety of causes. As Gilman
[1922] has stated environment, diet, endocrine secretions, impediments to coitus,
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excessive sexual use, infection and disease of sexual organs have all got a bearing
on sterility. It is known that animals that are closely confined, those that are
overfat as well as those fed on a deficient ration very frequently fail to bring forth
their young. Although the immediate concern of this resumé is what is termed as
functional sterility in the male, some of the factors are so interrelated that a few of
the more obvious causes, such as pathological lesions, anatomical deformities,
infections, metabolic disturbances of dietetic, endocrinal or genetic origin may be
briefly touched upon with profit.
The optimum condition for fecundation is that a normal spermatozoon should
meet a normal ovum in a normal environment. Any deviation from the optimum
condition leads to either temporary or permanent impairment of the reproductive
health and fertility of the sires, the diagnosis of which can usually be arrived at
from the breeding record, and a careful clinical or laboratory examination either
singly or combined. The ultimate value of a breeding sire is estimated by the
record of his performance. A clinical examination shows whether his general
behaviour, sexual desire, and ability to copulate freely are those of a normal and
vigorous male and it is to be expected that given good general care and mated only
to healthy females, the usefulness of the efficient sire will be maintained.
INFECTION.
Conditions such as obesity, muscular weakness or lameness, etc., may act as an
impediment to fertilisation apart from actual macroscopic and minute lesions
involving the genitalia or accessory organs. But infection appears to be the
greatest single factor. According to Williams [1923], "the failure of sixty per
cent. of the copulations to produce living young is referable to prenatal death
resulting from infection. If the infection kills or mortally injures the spermatozoa
in the seminal tubules or elsewhere in the male genitalia, if the infection is added
to the semen when ejaculated or later kills the spermatozoa or fertilised ovum, or
if the infection exists in the ovary, oviduct or uterus in the female the principle
remains the same ; it is death from genital infection ". Specific lesions of genital
infections like dourine, vesicular veneral disease, the veneral granuloma of dogs are
transmitted readily between the two sexes in coitus. Cultural examination of the
external genitalia of the sire is rendered difficult owing to the risk of contamination
with extraneous micro-organisms. The specific organisms of equine and bovine
abortion, streptococci, staphylococci, B. coli, B. typhosus, B. tuberculosis and
aspergillus have been recovered by workers from the testis, epididymis and seminal
vesicles and Williams [1926] records a case where a stallion so thoroughly and
uniformly infected his mares that of 19 only 3 conceived, of which one aborted, one
foaled a weakling and another produced an apparently healthy foal. Local inflam¬
DIAGNOSIS AND TREATMENT OF STERILITY IN STALLION AND BULL
187
matory conditions such as orchitis, epididymitis as well as infection elsewhere in
the body may inhibit or even abolish normal spermatogenesis.
HEREDITARY FERTILITY FACTOR.
That sterility may be due to structural malformations has already been men-
tioned. Gross imperfection of the genitalia, severe hernia and improper descent
of the testicles may be the expression of genetic action. According to Crew [1924]
grades of fertility are definite racial and breed characters and are transmitted in
inheritance and imperfections of the external genital organs are a part of the
general conditions of intersexuality and of hermaphroditism, both of which are
definitely genetical in nature. Richter [1926] and Wester [1921] lay great emphasis
on heredity in the causation of sterility of male goats and bulls. Crew points out
that chromosome aberrations lead to complete sterility and offers this as an expla-
nation of the common sterility seen in the offspring of an inter-specific cross, such
as a mule. He also brings forward cytological evidence in support of this con-
tention. In the case of another species cross, Bos americanus × Bos taurus, however,
there is probably a lethal factor as this cross is followed by the occurrence of
hydramnios during pregnancy resulting in maternal or foetal death.
ENDOCRINE FACTOR.
The correlation of function between the reproductive organs and other glands
of internal secretion are well known. Among the endocrines that bear a special
relation to sexual development and function are the anterior lobe of the pituitary,
the thyroid, the prostate and the adrenal cortex. Disease of the pineal gland may
involve premature sexual development. The thymus gland has an inhibitory
action on the growth of the sexual organs and becomes markedly reduced at
puberty. There is little doubt that some cases of sterility are due to a derange-
ment of this correlation. Hormones have now been extracted from many tissues.
Evidence is available to show that the anterior lobe of the pituitary contains at
least three hormones—a growth-hormone, a gonad-stimulating hormone and a lacta-
tion hormone. Chemically they have not yet been separated. The testicular
hormones are complementary to the pituitary hormones and induce sexual excite-
ment and secondary sexual characteristics even in the abnormal absence of the
testes.
ENVIRONMENT.
This is a minor factor associated with deficiencies in soil and fodder but seasonal
and climatic changes present certain stimuli to sexual instinct. Todd and Reynolds
[1931] consider that advancing the covering season for getting foals earlier in the
year, as has been done in England, has resulted in less fertility of stallions. It is
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stated that difficulties have been experienced by most breeders in getting mares in
foal until grass is available and this, in Todd's view, is due to the beneficial effects
of vitamins and sunlight in stabilising the endocrine balance. Further Sanders
[1926] showed that a stallion's fertility varies according to the district of the
country in which he stands or travels, being higher in the north and west of
England and Wales than in the south and east and very low in Scotland.
DIET.
There is ample evidence that nutritional deficiencies will modify the sexual
activity of the parent and of the spermatozoa, thus affecting fertility. Paul [1906]
was perhaps the first to show that fertility is affected by diet. Osborne and
Mendel [1919] noticed that although animals fed on artificial diets grew vigorously
to adult size, they were, with few exceptions sterile. Mason [1925] observed that
an increase in breeding capacity is brought about in stalled cattle by turning them
out on to green grass. It is known that lack of vitamins B and E in the diet
results in the degeneration of the germ cells and the seminal epithelium, although
growth and development may proceed in the normal way. With regard to mineral
deficiencies of phosphorus and calcium as a cause of sterility, low fertility and reten-
tion of placenta in cattle, Kelley [1932] refers to the experience of several colonial
and foreign authorities, in particular to Hindmarsh and Hopkirk. The former had
experience of a herd in which cattle were frequently sterile ; oestrum was exhibited
but conception did not take place. During the following year, they were given
a regular ration of bone meal with the result that practically all bred on to time.
Hopkirk has shown that the so-called Waihi Disease which is characterised by the
absence of oestrum is a deficiency condition being amenable to bone meal feeding.
Experimental evidence is available from Germany and elsewhere that sperm pro-
duction is greatly influenced by the feed. A basal ration of 15 pounds of oats and
15 pounds of hay resulted in a sperm production of 2,885,701,420 per ejaculation.
When the basal ration was supplemented by 10 hens' eggs and 5 lbs. of wheat bran
daily, the sperm production was approximately three times as great. A supplement
of dried peas and linseed cake increased the production over that seen with the
basal ration to about 50 per cent. only. Other proteins and lipoid substances
gave results varying between those obtained with the oil cakes and with the eggs.
Further experiments show that rats were inactive sexually when fed on whole
milk until copper and iron were added in small quantities. Deficiency of iodine
also has been proved to act detrimentally on sexual life and fertility. In Australia
potassium iodide is therefore added in small quantities to the ration. Another
agent which has been found useful in the female is wheat germ oil, but no record
of its use in the male has been found. From what has been said above, it will be
DIAGNOSIS AND TREATMENT OF STERILITY IN STALLION AND BULL
189
seen that a careful examination of the diet of a sterile animal is warranted although
he be apparently normal in condition.
SEMINAL PATHOLOGY.
Apart from the above factors, examination of the seminal fluid is of great value
in arriving at a correct diagnosis of sterility since the spermatogenctic function of
the testicle is very sensitive to outside influences. The influence of the frequency
of coitus on sperm formation has received considerable attention in Germany.
Studies of the quantity and quality of spermatozoa produced by stallions with
varying intervals between service indicate that the rest period between services
for normal spermatozoa production is 48 hours. Daily matings caused an increase
in the percentage of immature sperms. Matings after intervals of more than
two days did not result in an increase in the number of viable sperms. Sexual
stimulation did not appear to influence sperm production. Complete absence of
functional sperms may be due to atresia of the seminiferous tubules, non-develop-
ment of the interstitial tissue of the testis as in cryptorchidism. Williams and
Savage [1925] have published a comprehensive article on the micropathology of bull
semen, and by means of the head length measurement of the sperms projected
at 3,000 diameters, as recommended by them, Conklin [1930] has been able to
detect changes in the spermatozoa, referable to disease of the genitalia, long before
a clinical examination would show pathological changes.
COLLECTION OF SEMINAL FLUID FOR EXAMINATION.
It is more convenient and easier to collect semen from sires after service than
before. It is necessary to observe cleanliness, otherwise presence of smegma,
masses of epithelial debris, bacteria, pus, blood cells, and catarrhal discharge may
make the examination more difficult. The penis and preputial folds should be
thoroughly washed with soap and water and the vaginal cavity douched out with
a mild solution of salt or bicarbonate of soda before service is permitted. The
seminal fluid may be collected from the vaginal floor of the female with a spatula
or glass rod. It may not be necessary to use a vaginal speculum for the pur-
pose. Semen on emission may be caught direct into a beaker or test tube from
the tuft of hair at the ventral commissure of the vagina or from the penis by
pressure on the urethra of the sire.
PREPARATION AND STAINING OF SMEARS.
Wet.—The vaginal mucus or a drop of the semen from the glass vessel may be
smeared on a glass slide and another glass slide or cover slip put on it and exam-
ination made straightway under the high power of the microscope. If the
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semen is thick it is advisable to mount it in 0.9 per cent. saline solution or in
water only.
Dry.—The specimen smear is allowed to dry and it is fixed by passing it over
the flame a few times. Care should be taken not to char the specimen by bring-
ing it too near the flame or by holding it too long over it.
(i) The specimen is then stained with methylene blue for 20 minutes,
washed rapidly and counter-stained with eosin, washed thoroughly
and dried. The film may then be examined under the oil immersion
lens of the microscope.
(ii) Another useful stain is carbol fuchsin. It is used hot and placed
on the dried and fixed specimen for 10 minutes. The stain is poured
off and the slide was hed with water and dried and examined as be-
fore. This method stains the tail very well but at the expense of
some detail in the head and middle part.
(iii) Williams' modification. —The smear is fixed with heat and then
the mucus is removed by placing the film in a 0.5 per cent. chloro¬
zene solution for 8—10 minutes. The slide is now washed with
clear water (excess water removed by shaking) and stained with
carbol fuchsin with heat for 1 to 2 minutes. The carbol fuchsin
being washed off with water, the film is stained for 8 minutes with
alkaline methylene blue. Then wash off the methylene blue and
dry with filter paper. The head of the healthy cell is thus brought
out in clear detail, the nucleus remains red and the cytoplasm stains
a light blue.
(iv) Jenner's method requires no previous fixation and consists of only
a combined stain and fixative. It is a mixture of methylene blue,
eosine and methyl alcohol. The specimen may be mounted in xylol¬
balsam.
EXAMINATION.
The seminal fluid, besides spermatozoa, consists of secretions of epididymis,
seminal vesicles, prostrate glands and glands of Cowper. The spermatozoa are
present in enormous numbers in every ejaculation. Many millions are present
in a single ejaculation of a bull or a stallion.
A fully formed spermatozoon consists of an (i) egg-shaped head, which repre-
sents the cell nucleus, (ii) a middle piece or a short cylindrical body—the all-
important bright spot, the centrosome, is on the body, (iii) a long tapering tail—it
tapers to a point—moving from side to side—the greater the undulation of the tail
the greater the vitality of the spermatozoon. Spermatozoa are almost immobile
DIAGNOSIS AND TREATMENT OF STERILITY IN STALLION AND BULL
191
in the generative tract of the male, they become motile in the secretion of the
accessory glands and also in Ringer's solution. Their motility is most vigorous
in the normal fluids of a female generative tract.
Spermatozoa in the male passages or female generative tract may retain their
vitality and their power of fertilising ova for 30 days or more (rabbit), for 21
days (man). Recently it has been found possible to keep the semen of the male
in tubes in a fertile condition outside the body for 40 hours or more, and use it
for inseminating females at the end of this period.
To a person familiar with spermatozoa, the appearance is quite certain and de-
finite, but to distinguish a healthy spermatozoon from a weak and diseased one
and to distinguish a perfect one from a malformed one, requires considerable
experience and skill.
A simple determination of the presence or absence of sperms in the semen is
not enough. The secretion of the vagina is normally acid and is inimical to sper-
matozoa. If their motility is weak they are not able to continue their progressive
movement to reach and enter the cervix uteri. The rate of movement, morphology,
structure and staining reactions of the sperm have to be considered for a rational
diagnosis.
The popular impression that if the presence of a few motile spermatozoa is
demonstrated in the specimen of semen, fertility may be expected is not based on
scientific experience [Walker, 1929]. When one recollects the process of impregna-
tion of the ovum as observed microscopically one realises clearly that the fertility
of a given animal should be judged not merely by the numerical frequency of
spermatozoa and of the motility present, but by a further study of (a) duration and
(b) quality of motility, (c) the percentage of the motionless to the actively motile
sperms.
Specimens of semen may be collected at different periods after service and
the change in the characters of the sperm noticed for judging the vitality of the
sperms.
VITALITY OF THE SPERMATOZOON.
(a) Duration of motility is determined by—
(i) noting the number of hours the motility persists in unmixed semen,
(ii) by the number of hours motility persists in natural media (several
secretions of the female tract),
(iii) by the number of hours motility persists in various artificial media-
(b) Quality of motility of spermatozoa is, however, a more important criterion
for judging the vitality and efficiency of semen [Popa, 1929]. The following is a
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brief description of the three different kinds of motility—which follow each
other in natural sequence :—
(i) Progressive vibratile motion—is the motion that is first seen in fresh
semen under favourable conditions. It consists of a lashing of the after-
part of the tail from side to side so rapidly as to constitute a vibra-
tion—the undulation of the tail being almost imperceptible. It
produces a rapid forward motion in practically a straight line.
In the presence of a flow of current this motion takes place against
the current. It is particularly in evidence in the vaginal canal.
(ii) The second normal motion differs from the first only in degree of speed.
The undulations are plainly perceptible—the direction of motion
being determined by the surroundings.
(iii) The third is a slight burrowing motion, as if seeking a mooring place.
These kinds of motility are not unlike the movement of the caudal fin
of the fish.
In studying the motility of a specimen of semen, there are several other factors
which should be considered:—
(a) the time that has elapsed since the semen was ejaculated,
(b) the condition under which it has been kept,
(c) the viscosity of the semen.
Determination of sterility is easier by the character of motility and takes much less
time. After the vitality of the sperm has been estimated the defects in their struc-
ture and form have to be examined.
(c) Hydrogen-ion concentration of semen is another important factor. Even
when all other factors are ideal a mere change in the pH of the semen brings
about diminution or entire stoppage of the motility of the spermatozoa. Anderson,
Peter and Healey [1922] have shown that the pH of normal horse semen varies from
6.94 to 7.5 and that the average is pH 7.3. The pH from horses known to be
sterile varied from 7.49 to 7.76 and the average was 7.58. Nordby has recorded a
case of partial sterility in a boar on account of adverse hydrogen-ion concentration
in its semen. For the determination of the hydrogen-ion concentration of the
seminal fluid, this should be collected direct from the male animal [Donham, Sims
and Shaw, 1931].
DEFECTS IN THE SPERMS.
Numerous defects in the sperms are met with. Motility may be reduced
or be practically absent, duration of motility may be materially shortened from
a few hours to a few minutes, the character of motility may be changed from a
DIAGNOSIS AND TREATMENT OF STERILITY IN STALLION AND BULL
193
progressive vibratile motion to a to and fro lashing movement and the morphology
may be altered in the following ways:—
(a) The heads may be twice as large as normal and may take the pink of
Jenner's stain and frequently the neck and tail may stain blue. The
contents of the nucleus on the head may present defects.
(b) Sperms with a " U " shaped tail and normal head but always motionless.
(c) Wry-neck sperm with considerable motion.
(d) Large head stained blue with a very thick neck piece, a short tail with
slight motion.
A proper examination of the semen can only be carried out in the locality.
There is no satisfactory method for the despatch of semen for examination purposes
to distant laboratories. Motility tests are the most important of all in the diag-
nosis of sterility in the male and the available methods for transporting semen are
yet too undependable to maintain the proper motility of sperms in vitro. Expos-
ure to light and variation of temperature are inimical to the survival of the
spermatozoa in vitro. Dewar flasks and thermos flasks maintained between 20°-30°C
have been found the best for keeping spermatozoa suspended in physiological saline
active and protected from light. Variation in temperature alters the composition
of the fluid.
TREATMENT.
The local or general cause of sterility having been determined, treatment is
prescribed accordingly. A perusal of the literature shows that most workers have
advised elimination of sterile sires from the herd on the apprehension that such
sires may transmit their undesirable breeding qualities to the progeny. Bulls
suffering from low fertility or sterility have been castrated or sent to the slaughter
house. The available methods of treatment of sterility are therefore appli-
cable in the case of females only [Kohn, 1930; Stalfors, 1930], and no
helpful reference to the practical application of endocrinology in cases of male
sterility exists. Further it seems that no reliable standardised product for veteri-
nary use has yet been put on to the market.
A number of preparations have been described which, given by injection or in
some cases by the mouth, stimulate the sex glands. The principal sources of the
active principle are the anterior lobe of the pituitary [Evans, 1923], and the urine
of pregnant women. Zondek and Aschheim [1927] have also demonstrated that useful
effects can be produced by the use of the urine of pregnant cows and since then
this work has been extended to include other animals of economic importance
[Crew, Miller and Anderson, 1931; Kust, 1932]. Several workers have observed the