Veterinary
Gynaecology
VCT 502
S.’Tona Olurode
DVM,MVSc.(Theriogenology)
Dept.of Vet.Public Health&Reprod.
College of Vet.Medicine,UNAAB
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Learner’s objectives
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Define the basic concepts and terminologies in Theriogenology
Review the normal anatomy and physiology of the female
domestic species
Carry out comparism of the reproductive features
Define and Describe placentation
Define pelvimetry and conceptualize its importance
Discuss female reproductive hormones
State the various hormones of female reproduction and their
functions
Define steroidogenesis
Define Puberty and explain factors associated with its onset
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INTRODUCTION TO
THERIOGENOLOGY
Definition: term derived from 3 Greek
words- Therion beast
Genan
- to produce
Logus
- study of
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Introduction contd’
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Theriogenology can be defined as
that branch of Veterinary Medicine
which deals with reproduction, including
the physiology and pathology of male
and female reproductive systems and
the clinical practice of veterinary
obstetrics, gynaecology and
semenology.
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Veterinary Gynaecology
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that branch of medicine which treats
diseases of the genital tract in the
female.
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Veterinary Obstetrics
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It is that branch of veterinary science which
deals with the necessary or advisable aid
during the act of parturition in all animals
coming under the purview of the veterinarian.
It is the art of managing cases of animal
birth. It is that branch of surgery which deals
with the management of pregnancy, labour
and puerperium (the period from the end of
the 3rd stage of labour till completion of
uterine involution).
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Anatomical review of female
reproductive tract: The Pelvis
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The pelvis is the smallest and most posterior of the
three great cavities of the trunk, and is of
considerable importance to the obstetrician on
account of its rigid wall, and the resulting resistance
which it presents to the passage of the fetus as a
result of any variation from the normal.
The attachment of the vulva to the pelvis constitutes
the only fixed base of support for the vagina, cervix,
and the uterus. This attachment enables the uterus
at the time of parturition, to contract longitudinally in
a manner which aids in dilating the birth canal and
forcing the foetus towards the vulva.
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Review contd’
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Pathologically, the pelvis is of limited interest in
veterinary obstetrics as compared with human
obstetrics. The quadrupedal position of the domestic
animal largely relieves the pelvis of weight-bearing,
thus preventing deformities from pressure upon
diseased pelvic bones, and as such renders pelvic
deformities comparatively rare.
The pelvis is formed by both bony and ligamentous
structures.
The bony pelvis is bounded at the sides and below by
the two coxae and above by the sacrum and first
three coccygeal vertebrae.
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Review contd’
The os coxae each consists of an
ilium, ischium and pubis. These paired
bones form the chief boundary of the
pelvis and the framework of the
uppermost segment of the hindlimbs
which it connects with the spine.
 The Sacrum: Consists of a series of
five fused vertebra in the horse and
ruminants, four in the pig, and three in
carnivora.
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Review contd’
The ligamentous portion of the pelvis
consists of:
(i) The dorsal and lateral sacro-iliac
ligaments
(ii) The sacro-sciatic ligament
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Functions of the Sacro-Sciatic
Ligaments:
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furnish attachments for the vulva and gluteal
muscles
prevent the posterior portion of the pelvis or
ischia from rescinding from the sacrum.
form a strong, flexible, and yielding wall to
the pelvic cavity.
Under pressure of parturition, they yield
sufficiently to allow the constricted pelvic
outlet to equal in dimensions the larger bony
inlet of the pelvis.
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Articulation of the Pelvis
There are five (5) pelvic articulations:
1.
Sacro-lumbar
2.
Right sacro-iliac
3. Ischio-pubic symphysis
4. Sacro-coccygeal
5. Left sacro-iliac
These articulations are important in
obstetrics because they become flexible at
the time of parturition.
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Pelvimetry
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In all species, the pelvic inlet is roughly
oval in shape with the sacro-pubic
diameter being the largest. The sow
and cow have the most elliptical pelvic
inlets while the mare and some dogs
have inlets that are nearly rounded.
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Pelvimetry contd’
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The term pelvimetry refers to the measurement of
the dimensions of the pelvic cavity. In human
obstetrics, pelvimetry has been a routine part of the
prenatal management of the expectant mother to
determine ease of delivery. This procedure was given
very little attention in veterinary obstetrics until the
last decade. At the present time there is a great deal
of interest in pelvimetry and the information obtained
is being utilized to reduce the incidence of dystocia in
heifers of beef breed.
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methods used in determining the
dimensions of the pelvic cavity:
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1. External or indirect pelvimetry is
carried out by calculating the pelvic
diameter based on measurements taken
between the angles of the ilia, the
distance between the ischia and the
height from the hip joint to highest
point of the croup. In general, this
method has been shown to be
inaccurate and is no longer used.
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Methods of pelvimetry
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2. Internal or direct pelvimetry
refers to the measurement of the
interior of the pelvis through the rectum
with a pelvimeter.
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Pelvimetry procedure
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The general procedure is to restrain the
animal in a chute with light squeeze. A
comfortable normal standing position is
the best. Faeces should be removed
from the rectum and the instrument
carefully inserted into the rectum with
the hand and arm to the pelvic inlet.
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FEMALE REPRODUCTIVE
SYSTEM
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The female reproductive system
consists of the ovaries and the female
duct system. The duct system includes
the oviducts (fallopian tube/uterine
tubes), uterus, cervix, vagina and vulva.
The ovaries originated from the
secondary sex cords of the genital ridge
while the duct system arose from the
mullerian ducts (a pair) which appear
during early embryonic development.
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Ovarian shapes in female animals
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The ovary of the cow is almond-shaped, but the
shape is altered by growing follicles or corpora lutea.
The average size is about 35 x 25 x 15mm which is
larger in cows with active ovaries than those with
inactive ovaries.
The ovaries of ewe and doe are almond-shaped and
less than half the size of that of the cow.
The ovaries in the mare are kidney (or bean)-shaped
and are two or three times larger than those for
cows.
The ovaries in the sow are slightly larger than those
found in the ewe and appear as a “cluster of grapes”.
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UTERUS
Four basic types of uteri are found in
animals viz:
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Bicornuate
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Duplex
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Simple
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Bipartite
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Placentation
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The endometrium provides a mechanism for
attachment of the extra-embryonic membranes. This
union forms the placenta through the process called
PLACENTATION which aids in the transport of
nutrients from the maternal blood to embryonic or
foetal blood as well as waste product removal from
the foetal blood through the maternal systems.
The nature of the placental attachments differs
among species.
Chorionic villi from the extra-embryonic membranes
penetrate into caruncles which are button-like
projections on the endometrium. This union forms
the PLACENTOME.
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Placentation-classification
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The placental attachment of the mare, sow,
doe, ewe and cow is classified as
epitheliochorial.
In humans and monkey, it is haemochorial.
In dog and cat, it is classified as
endotheliochorial whilst
in rat, rabbit and guinea pig, it is classified as
haemoendothelial.
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Placentation
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FEMALE REPRODUCTIVE
HORMONES
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Hormones are molecules that function
as a message carrier within an
organism, its only function is to convey
information. Hormones are chemical
agents which are carried by the blood
to cells within a target organ of other
target cells where they regulate a
specific physiological activity.
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1) Endocrine glands:
Don't have ducts.
Secrete hormones internally into blood stream.
2) Exocrine glands:
Have ducts.
Secrete externally into ducts.
Definition of Hormones:
Chemical agents which are carried by the blood to cells within a target
organ or other target cells where they regulate a specific physiological
activity.
Definition of Receptor sites:
1) Recognition units in cells that have a high affinity for a particular
hormone
2) Chemically: Protein
3) Hormone + receptor site: initiates reactions within cell which bring about
the specific physiological response within that bound hormone.
4) Location of receptor sites in a cell:
Cytosol receptor: For steroid hormones
Membrane receptor: For peptide or protein hormones
5) Concentration of receptor sites in a target organ:
increase or decrease depending on the endocrine status of the animal.
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Hormone - Chemical messenger produced by
a ductless gland or tissue and carried in the
blood to a target organ where it effects a
change in cellular activity.
Functionally; reproductive hormones are
classified into:
Primary hormones: regulate the various
reproductive processes
Metabolic hormones: which indirectly influence
reproduction.
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Classification According to their
Chemical Structure
Proteins:
*Are Polypeptide hormones,
*M.W=300-70,000 Daltons.
*Because they are easily digested by enzymes, they
cannot be given orally, but must be administrated by
injection.
Steroids:
*M.W.=300-400 Daltons.
*Natural steroids are not effective by oral administration,
but synthetic or plant steroids can be administrated
orally and by injection.
Fatty Acids:
*M.W.= 400 Daltons
*Can be administrated only by injection.
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Hormones that Regulate
Reproduction: Hypothalamus
Hormone
Gonadotropin
Releasing Hormone
(GnRH)
Chemical Class
Principal Functions
Peptide
FSH & LH release
Prolactin Inhibiting
Factor (PIF)
Peptide
Prolactin Retention
Prolactin Releasing
Factor (PRF)
Peptide
Prolactin Release
Corticotropin Releasing
Hormone (CRH)
Peptide
ACTH release
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Hormones that Regulate
Reproduction: Anterior Pituitary
Hormone
Follicle Stimulating Hormone)
(FSH
Chemical Class
Protein
Principal Functions
Follicle Growth
Estrogen Release
Spermiogenesis
Luteinizing Hormone (LH)
Protein
Prolactin
Adrenocorticotropin (ACTH)
Posterior Pituitary Oxytocin
Synthesis in Hypothalamus
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Protein
Ovulation
CL formation & function
Testosterone Release
Milk Synthesis
Polypeptide
Release of Glucocorticoids
Peptide
Parturition
Milk Ejection
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STEROIDOGENESIS
The two cell steroid production theory
states that:
 Theca cells produce androgens under
the influence of Luteinizing hormone
while
 Granulosa cells convert the androgens
to oestrogens under the influence of
FSH.
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PUBERTY IN FEMALE ANIMAL
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It is defined as the achievement of the
ability to reproduce or attainment of
sexual maturity. It is the ability of an
animal to release gametes and manifest
complete sexual behaviour sequence.
Irrespective of the mechanism, the
attainment of sexual activity is a
gradual process which is not a single
event and occurs over a period of time.
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Puberty contd’
The onset of sexual activity is
associated with decreased sensitivity of
the hypothalamo-hypophyseal axis to
negative feedback control of the
gonadal steroids.
 In the prepubertal animal, the
hypothalamo-hypohyseal axis is very
sensitive to low levels of the gonadal
steroids
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Puberty contd’
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This decrease in sensitivity to negative
feedback of gonadal steroids i.e.
allowing higher levels of
gonadotrophins (FSH and LH) required
for cyclicity results in the initiation of
PUBERTY – this is termed “GONADO
STAT” theory.
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Age of puberty
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Bitch:
Cow:
Dow:
Ewe:
Mare:
Queen:
Sow:
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7
4
6
1
7
6
–
–
–
–
–
–
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20 months
18 months
8 months
15 months
2 years
12 months
8 months
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FACTORS AFFECTING THE
TIME OF ONSET OF PUBERY
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Genotype
Nutrition
Season of the year
Proximity of the male animal
Environment
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Nutrition
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Very important factor especially in the
ruminants
Generally occurs when 55-65% adult
body weight is attained
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Thank you all for your attention and
patience
Do you have question (s)?
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