Infertility in male animals

1. INFERTILITY IN MALE ANIMALS

2. Mating behaviour
 Fertility or reproductive capacity of the individual bull is a crucial factor in
determining the reproductive performance of cows, i.e., a plentiful supply of
normal spermatozoa is essential, as is the sexual desire (libido) which ultimately
leads to the ejaculation of the spermatozoa into a real or artificial vagina.
 The act of copulation consist of sexual excitement, courtship, erection,
mounting, intromission, ejaculation, withdrawal and dismounting.
 There is greater variation in the duration of these components between species
and individual males within a species.
i) Stallion 1- 3 min. ii) Boar 4 - 6 min.
iii) Dog 5 - 45 min. iv) Bull 5 -10 sec
v) Tom 10 sec. vi) Ram /Buck 3 - 5 sec

5. INFERTILITY IN MALE ANIMALS
 Reproductive abnormalities causing absolute or relative infertility in male
animals are divided into three main classes;
a) conditions causing failure of normal service (impotentia coeundi)
b) conditions causing failure of conception after normal service (impotentia
generandi).
c) Miscellaneous diseases affecting the reproductive organs.
 Potency is the physical capability of the entire body to coordinate and perform
the male’s normal role at coitus including erection, mounting, intromission and
ejaculation.
 A lack of potency is observed in males of all species and is characterized by
complete lack of sexual interest, inability to copulate, exhibit libido, mount
and copulate.

6.  Libido is the sexual desire or sex drive.
 Libido is primarily dependent upon androgenic steroid hormones, which allow mating
and aggressive behaviour to occur, as well as maintaining the function of all parts of the
male reproductive system.
 Although sex drive or libido is largely genetic in nature, it is subjected to great
modification by many environmental or physical factors including;
1. Nutrition - deficiency of protein, vit. A, zinc, phosphorous, cobalt and obese reduce libido!
2. Systemic diseases- any chronic of acute severe disease will cause loss of sexual desire
3. Age - very young males and old males frequently exhibit reduced –to-complete lack of libido.
4. Management practices - for semen collection, the presence of other males near the mount
animal or in sight of the breeding males increases libido and thus volume of semen.
5. Cognitive /mental factors – interfere with normal coitus resulting into impotency.

7.  Inability to copulate is a relatively frequent cause of infertility in domestic
animals.
 Conditions that cause failure of copulation include failure of the penis to become
turgid (i.e. failure of erection), abnormalities of erection that prevent
intromission, and lesions of the penis and prepuce that prevent protrusion of
the penis.
 Failure of erection is due to either abnormal venous drainage of the corpus
cavernosum penis (CCP), occlusion of the longitudinal canals of the penis or
rupture of the corpus cavernosum penis.
 Abnormalities of erection are caused by either persistence of the penile
frenulum, congenital abnormalities of the penis preventing protrusion or causing
deviation of the penis.
Failure of normal service: impotentia coeundi

8.  Lesions of the prepuce and/or penis include preputial injuries, Balanoposthitis,
Phimosis, Paraphimosis and penile neoplasia.
a) Phimosis; stenosis / stricture of the preputial orifice that prevents the penis from being
protruded.
o Stenosis of the preputial orifice is usually acquired following injuries, wounds and
infections in bulls.
o Congenital stenosis of the external preputial orifice is common in dogs and is
surgically corrected by a dorsal incision of the orifice.
b) Paraphimosis is the inability to withdraw the penis into the prepuce results into
edema, swelling and balanoposthitis.
o It may arise either from congenital or acquired strictures of the prepuce, paralysis of
the penis and, occasionally, from balanoposthitis.

9. c) Penile neoplasia. These are common in dogs, bulls and horses.
o Penile tumors in bulls are virus- induced fibropapillomata of the skin, genitalia and
alimentary tract and are common in young cattle.
o Penile Squamous cell carcinomata of the glans penis or preputial ring are common in horses.
o In the dog, the most common penile tumour is the transmissible venereal.
o Clinical effects vary according to the size and the morphology of the lesions; Haemorrhage,
ulceration and pain are common sequelae, and these may impair libido.
o Treatment, where this is possible, is by surgical removal of the tumour. Also the use of
chemotherapy (Vincristine) has been advocated.

10.  Fertility in bull is defined as the normal functioning of the testes, accessory glands
and ducts to deliver sperm of normal quantity and quality.
 Impotentia generandi is caused by many factors including; acquired diseases or
pathological lesions of testes, and congenital or hereditary diseases of testes (e.g.
hypoplasia) .
 Fertilisation failure, despite normal copulation, may be caused by diseases of the
testis, epididymis and accessory glands resulting into sperm defects/spermatozoa
morphological defects, reduced sperm concentration and motility.
 Common sperm defects that may cause infertility include acrosome defect
(knobbed sperm), decapitated sperm, pear shaped head, stump tail, proximal
droplet and strongly folded/coiled tail (Dag defect)
Conception failure after normal service:
impotentia generandi

11.  Abnormal spermatozoa are produced mainly as a result of defective
spermatogenesis and, this may be genetic in origin or may be due to
disease or adverse environmental conditions.
 For example, high environmental temperatures have been reported
to cause an increase in the proportion of sperm abnormalities.

12. Pear-shaped head
‘knobbed sperm’ defect
detached normal heads
Defects of the sperm head

13. Defects of the sperm midpiece and tail
Coiled-tail’ – a defect of
formation of the midpiece,
Dag’ defect, Fractured neck,
Accessory tail Terminally coiled tail Tail-stump defect.

14. a) Umbilical and ventral hernia.
b) Short penile bone in dog associated with a long flaccid cranial portion of the penis
causing difficult to direct into the vulva at coitus.
c) Loss of sensory innervation of the glands penis.
d) Vascular shunts causing failure of erection.
e) Urinary calculi lodging in the urethra.
f) Pain caused by infection of the genital organs or peritoneum may cause impotency
or refusal to copulate.
Miscellaneous causes for loss of libido or
inability to copulate

15. Testicular hypoplasia.
 Testicular hypoplasia implies an incomplete development of the germinal
epithelium of the seminiferous tubules, due to inadequate numbers of germinal
cells within the testis.
 It is a congenital and hereditary condition and can be unilateral or bilateral, partial
or total.
 Lack of germinal cells may arise through partial or complete failure of germinal
cells to develop in the yolk sac, failure to migrate to the gonad or failure to
multiply in the gonad.
 Noted at the time of puberty or later in all domestic animals, most commonly in
bulls, rams, boars and stallions.
 The symptoms of testicular hypoplasia in bulls vary greatly. In most cases sexual
desire is excellent and coitus is prompt.

16.  Mild cases may exhibit moderate oligospermia or poor sperm morphology, but
severe cases may be aspermic.
 Diagnosis of the condition is by measurement of scrotal circumference, a value
below acceptable limits for the species and breed being diagnostic.
 Palpation of the testes reveals one or both to be small and flabby, but regular in
outline and freely movable in the scrotum.
 Semen analysis may reveal aspermic or oligospermic ejaculates, sometimes with
markedly abnormal morphology or motility characteristics.
 Histologic section may reveals one-half to two third of the seminiferous tubules
are underdeveloped
 Because of the probable inherited basis of testicular hypoplasia, castration and
(for meat animals) slaughter for recovery of the carcass value should be
recommended.

19. Testicular degeneration.
 Testicular degeneration occurs in response to raised intratesticular temperature,
toxins, endocrine disturbances and infection.
 The seminiferous epithelium of the testis is highly susceptible to damage, with a
wide variety of agents causing reversible or irreversible degeneration including
temperature , toxins and infections
 Raised temperature in the testis can itself emanate from many causes.
o Raised ambient temperature
o Abnormalities of the testicular circulation
 Toxic causes of testicular degeneration include heavy metal or radiation
contamination leading to testicular damage.
 Many infectious causes of degeneration such as Brucellosis, IBR

20.  Major clinical signs of degeneration are infertility and oligospermia usually
appearing 4–8 weeks after the onset of the cause of the degeneration.
 The ejaculate volume is unaffected, but the number and motility of spermatozoa
fall, while the proportion of sperm exhibiting abnormal morphology is high.
 In more severe cases, the ejaculate may become virtually aspermic, permanent
loss of seminiferous tubules occurs, with fibrosis and calcification of the testis.
 The semen picture will show a low concentration of spermatozoa and the
possible presence of few giant cells.
 Severely affected testes are small (one-third to two-third normal size), shrunken,
firm, or occasionally softer, with irregular outlines.

21.  Affected bulls will have small firm epididymis especially in the tail region
indicating reduced spermatogenesis and low gonadal sperm reserve.
 Spermatic cord of hypoplastic testicles are shorter and the testes are less heavy
and the scrotum smaller than in normal bulls.
 Histologic section:
o Will reveal one-half to two-thirds of the seminiferous tubules are
underdeveloped.
o There will be varying degrees of spermatogenesis; few spermatogonia,
spermiocytes, spermatids and abnormal to normal mature spermatozoa.

22. Normal testicle
Degenerated testicle

23. Semen changes during testicular degeneration
 The initial changes in semen quality during testicular degeneration are a
decrease in motility and an increase in the percentage of abnormal
sperm, particularly sperm with proximal droplets and primary defects
(head and midpiece defects).
 If the semen is being cryopreserved, a quick decline in post-thaw motility
may occur.
 Sperm numbers generally decrease, although ejaculate volume is usually
unaffected.

24. Sperm morphology from a bull with severe testicular degeneration. Many abnormal
cells are present, including sperm with abnormal heads, detached heads, defects of
the midpiece and sperm with proximal droplets

25. Male intersexes
 Intersexuality may arise from aberrations of genetic or chromosomal origin
and aberrations of gonadogenesis.
 Male pseudohermaphroditism is found in the caprine, porcine and
occasionally the bovine and equine.
 True hermaphroditism is seen in goats, dogs, pigs and cat and characterized by
ovotestes, no scrotum, an underdeveloped penis, uterine tissue and vesicular
glands.
 True hermaphroditism in goats is caused by a single recessive sex-linked gene,
and characterized by intra-abdominal testes, and external genitalia of
intermediate type.
 Intersexes in pigs are common with affected animals being genetically females,
have intra-abdominal testes, and externally have small vulva with prominent
clitoris.

26. Cryptorchidism.
 Cryptorchidism occurs when the normal process of testicular descent is disconcerted, such
that one or both testes fail to complete their descent into the scrotum.
 Spermatogenesis is generally markedly impaired or absent in testes that are not scrotal, due
to high intratesticular temperature.
 Animals that have a single cryptorchid testis are usually fertile, although the inhibition of
spermatogenesis in retained testes means that the sperm density is often below expectation
for the species.
 Where both testes are cryptorchid, the ejaculate is either aspermic or very severely
oligospermic.
 Testosterone secretion is unaffected by a cryptorchid position, so the libido of affected
animals is normal.
 Cryptorchidism occurs most commonly in the stallion, boar, in some breeds of dog, and
occasionally in bulls and rams.
 Testes may be retained in the abdomen or inguinal canal.

28. Orchitis and epididymitis.
 Orchitis ranges from a mild infection of the testis, through to gross suppurate or
necrotic destruction of the organ.
 Orchitis can arise from a primary infection or by haematogenous spread of
bacteria into the testis superinfecting pre-existing traumatic viral or parasitic
damage.
 Primary testicular damage can arise from infection caused by Brucella species,
Mycobacterium tuberculosis, Arcanobacterium) pyogenes etc.
 The infection may be purulent, with large, coalescent abscesses occupying much
of the testicular parenchyma, or it may be necrotic, when the substance of the
testis is almost entirely destroyed.
 If bilateral orchitis occurs, the prognosis for future breeding is hopeless, and
castration should be performed as soon as it is safe to do so.

29.  Epididymitis can also occur as a primary infection or by spread from an infected
testis.
 The general signs of epididymitis are similar to those of orchitis: namely, heat,
swelling and pain of the affected organ.
 Any inflammation of the epididymis causes obstruction of the single, highly
convoluted tube of which the organ is composed, so a loss of normal function.
 Unilateral epididymitis therefore results in reduced fertility, whereas bilateral
obstruction results in sterility.
 As with orchitis, unilateral epididymitis causes temperature - induced
degeneration in the contralateral testis, so early removal of the affected
epididymis and its associated testis should be recommended.

30. ABNORMALITIES OF SEMEN
 Semen can be collected by either artificial insemination,
electroejaculation, rectal massage of the internal genitalia or digital
manipulation, and assessed so as to provide information about the
fertilizing potential of the ejaculate.
 The assessment involves the numbers of sperm (concentration), motility,
morphology, and the presence of extraneous material in the ejaculate.
 Some sperm cell defects in cattle are inherited and these include, Dag
defect, tail stump defect, acrosomal defect or knobbed spermatozoa.