dog reproductive anatomy and physiology

Reproduction in the Dog

OviductOvary

Vagina

Cervix

Vulva

Uterine Horn

Uterine Body

FossaClitoridis

Clitoris

UrethralOpening

ConstrictorVestibuli

Reproductive Tract Anatomy of the Bitch

Oviduct

Uterine Horn

Uterine BodyMesometrium

Cervix

Vagina

Vulva

Ovary

Reproductive Tract Anatomy of the Bitch

OvaryOpening of Ovarian Bursa

MesovariumOvarian Bursa

Uterine Horn

OvaryCompletely enclosed with a fat covered peritoneal lining that is called the ovarian bursa.

Uterus During Estrus

Cervix and Vagina

Cervix

Vagina

Vagina, Vestibule and Vulva

Vestibule

Vagina

UrethralOpening

Clitoris

Vulva

FossaClitoridis

ConstrictorVestibuli

Reproductive Tract Anatomy of the Male

Rectum

Bladder

Vas Deferens

ProstateUrethralisMuscle

Glans PenisBulbus Glandis

Penis

ScrotumTestis

Epididymis Os Penis

Reproductive Tract Anatomy of the Male

BladderProstate

Vas Deferens

UrethralisMuscle

BulbocavernosusMuscle

Penis

Scrotum

Bulbus Glandis

CruraGlans Penis

Scrotum, Testis and Epididymis

Scrotum

Testis

CaputEpididymis

CorpusEpididymis

Spermatic Cord

Pampiniform Plexus

Tunica Vaginalis Parietal

StratumSubdarticum

ExternalCremaster Muscle

Testis, Epididymis & Spermatic Cord

Vas Deferens

Pampiniform Plexus

Testis

CaputEpididymis

CorpusEpididymis

CaudaEpididymis

Testis Anatomy

Vas Deferens

CaudaEpididymis

CorpusEpididymis

Testis

Bulbus Glandis

Bulbus GlandisPenis Glans Penis

• Vascular shunting allows swelling of penis for erection.

• Glans penis swells (Bulbus glandis) for locking penis in the vagina of female.

Os Penis and Bulbus Glandis

Os Penis

Vascular area of Bulbus Glandis

Penis

Os Penis

Bone

Os Penis

Groove

I. Ejaculation

a) Occurs within 80 seconds (sperm rich fraction).

II. Semen Characteristics

a) Three fractions

1) Clear fluid (Urethral Gland): 0.1 - 3.0 ml

2) Milky fluid (Sperm Rich): 0.5 - 4.0 ml

3) Clear fluid (Prostate Gland): 1 - 30 ml

Canine Physiology and Reproduction: Male

Canine Physiology and Reproduction: Bitch

I. Physiologya) Puberty

1) 6 to 7 months (range 4 to 22)2) Breed dependent® Smaller breeds earlier than larger

b) Oestrous cycle1) Type: mono-estrus® Indication of seasonal: Feb to May® Cycle randomly throughout year

2) Length between cycles

2) Length between cycles

® Mean: 7 months (range 4–13)

3) Stages

® Proestrus: 9 days (range 2–27)

• Physical turgid swelling of vulva and appearance of a bloody discharge

• Vaginal cytology will change with very early non-cornified epithelial cells increasing towards end ofproestrus.


• Behavior - bitch is restless and secretes pheromones but is aggressively negative towards male becoming more passive towards start of estrus

® Oestrus: 9 days (range 3–21)

• Bitch accepts male

• Vulva swelling will soften and discharge will be slightly pink to straw-colored.

• Vaginal cytology will have a high concentration of cornified epithelial cells with little debris.



• Discharge is straw colored rather than blood stained

® Metoestrus: 90 days

• Non-acceptance of males

• Loss of vulva swelling and no discharge. Vaginal cytology is nocornified cells and high numbers of White Blood Cells.

® Anoestrus: 75 days

• Period of ovarian inactivity and no vaginal discharge

• Breed dependent


® Pseudo-pregnancy:

• Extension of metestrus period in which progesterone concentrations remain elevated.

• Female will have nest building behavior and enlarged mammary glands

Behavioral Changes During Estrus in the Bitch

-8 -4 0 +4 +8 +12

Proestrus Estrus

Aggressivetowards Male Passive Provides sexual posturing

to male for copulation

Bloody dischargefrom vulva Copulation

Vulva Swollen and Enlarged

Indicates Day of Peak in LH


c) Ovulation1) Associated with LH peak ® Ovulation: 48 hours post LH peak® Oocyte maturation

• 4-5 days post LH peak• 2-3 days after post ovulation

® Peak fertility• 0-5 days

2) Detection of ovulation® Vaginal cytology

• Only accurate for detecting oestrus

Cell Type Para basal Small Large Anuclear Red NeutrophilsIntermediate Intermediate Keratinised Blood

Proestrus Early +++ +++ +/- - + +Late + ++ ++ ++ +++ -

Estrus Early - - +++ ++++ ++ -Late - - +++ +++ - +

Metestrus Early - + - +/- - +++Anestrus ++ + - - +/- +

Vaginal Cytology in the Bitch

Vaginal Cytology - Early Proestrus

SmallIntermediate Cells

Parabasal Cell

Vaginal Cytology - Proestrus

Red Blood Cells

Vaginal Cytology - Proestrus

LargeIntermediate Cells

Parabasal Cell

Red BloodCell

Vaginal Cytology - Early Estrus

Vaginal Cytology - Estrus

Large Intermediate

Anuclear Keratinised

Vaginal Cytology - Diestrus

Neutrphils

Neutrphils

Small Intermediate-Parabasal

Vaginal Cytology - Anestrus


2) Detection of ovulation (cont)® Progesterone concentrations

• Progesterone concentrations rise prior to ovulation

• Follicles start to luteinizebefore ovulation

• Progesterone concentrations can be measured to determine day of ovulation and breeding, but concentrations are highly variable

• Baseline Progesterone = 1 ng/ml

• Day Preceding Ovulation = 3-4 ng/ml

• Day of Ovulation = 4-8 ng/ml

-10 -6 -4 -2 0 2 4 8 12 14

Hormonal Patterns During Estrous Cycle of BitchA

rbitr

ary

Pla

sma

Con

cent

ratio

ns

Days from LH Peak

Estrogen

LH

Progesterone

Ovulation

Fertile Period

Completionof Meiosis I

Fertilization

Arb

itrar

y P

lasm

a C

once

ntra

tions

0 10 20 30 40 50 60 70Days of Pregnancy

MatingParturition

ProgesteroneProlactin

Corticosteroids

Total Estrogens

Hormone Concentrations During Pregnancy and Parturition

d) Mating – only when Bitch is in standing heat1) Dog achieves intromisssion by vigorous

thrusting of hind quarters2) Bulbus glandis swells (6x4 cm) in vagina3) Male dismounts, but remains connected

and facing away from Bitch, penis bent at a 180° angle

4) Vulva sphincter muscles contract around penis forming “ copulatory tie”® Ejaculation of seminal fluid (2-30 mL)® 20 minute average (range 5–60)® Not essential for conception


Mating in dogs

First Stage of Coitus

The “Turn”

Second Stage of CoitusThe “Tie”

Semen Collection of Male

Extension into AV

Ejaculation

The Turn

e) Pregnancy

1) Duration: 63 days (range 58 – 68)

2) Diagnosis

® Abdominal Palpation: day 21-28

® Radiography: day 45

® Ultrasonography: day 24-28

f) Parturition

1) Signal for initiation

® Maturation of fetal pituitary-adrenal axis via cortisol secretion


2) Impending signs of parturition

® Behavior: nest building, restlessness and seeking quiet, out of sight areas

® Vulva becomes swollen, edematous and may have some vaginal discharge

® Relaxation of pelvic and abdominal muscles

® Presence of milk in mammary gland is not an accurate sign

® Decrease in body temperature from 38 to 37oC just before parturition.


3) Stages of parturition

® First: mean 4 hours, last up to 36

• Period in which the cervix dilates

• Bitch will be uneasy, refuse food, pant, vomiting and frequently looking at flank.

® Second:length variable

• Visible straining of bitch in the sitting position

• Placental membrane will break and fluid discharged from vulva


® Second: cont

• Amnion covering the pup will be visible as it passes through the cervix, vagina and out the vulva

• Membrane will rupture spontaneously or by licking of dam

• Start of labor (active contractions) first fetus cannot be expected to survive more than 6 hours in the uterus

• Fetuses delivered within 2 hours of each other


® Second: cont

• Usually interval between puppies is about 30 minutes

® Third:

• Foetal membranes expelled 5-15 minutes

4) Dystocia- difficult birth

® Symptoms

• Abnormal fetal presentation, position or posture


4) Dystocia- difficult birth® Symptoms (cont)

• Strong and persistent labor for 20 minutes without delivery of fetus

• Weak and infrequent contractions for 2 to 3 hours

• > 4 hours from delivery of last fetus (if not last one)

® Causes• Most common is uterine inertia

(weak contractions), size of fetus and birth canal


Preparation for Parturition in the bitch

Bitch should be placed in a whelping box at least one week prior to parturition. Whelping box should be raised above the floor and large enough for the bitch to move freely. Bottom of box should be covered with newspapers for easy cleaning. It is necessary to have rail along the inside of the box to prevent puppies from being laid on.

Whelping BoxClean bedding and light source for heat

Picture courtesy Dr. Joseph McCann, RockErin Kennels

Side Rail protect pups from being laid on by bitch


Whelping BoxEasy access by bitch to nurse


dog reproductive anatomy and physiology

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