This document summarizes canine reproduction, including the anatomy of the reproductive tract in bitches, the estrus cycle, signs of estrus, ovulation and breeding. It discusses pregnancy in dogs from fertilization through parturition, including typical gestation length and stages of labor. Pseudopregnancy is also summarized briefly. Key details provided include typical cycle lengths, hormone changes, vaginal cytology patterns through the cycle, and behaviors associated with each reproductive stage in dogs.

1. THER 608
Physiology of Reproduction
Prof. Dr. Nasim Ahmad
Canine Reproduction
Puberty, anatomy, estrus cycle, vaginal cytology,
ovulation, breeding, pregnancy, parturition
1

2. Reproductive Tract of the Bitch
Ovary Oviduct
Uterine Horn
Uterine Body
Cervix
Vagina
Vulva
Clitoris
Fossa
Clitoridis
Urethral
Opening
Constrictor
Vestibuli

3. http://www.goddardvetgroup.co.uk/images/anatomy_physiology_6.jp
Bulbis
glandis
Clinically important, BPH,
abscess
Seminal vesicles (absent)

4. Puberty
• Occur at 6-24 months. Vary due to size,
nutrition, breed, social factors.
• First estrus tends to be irregular (split heats).
Seasonality
• Breeders believe that there are two breeding
seasons a year. However kennel club data do
not support it.
• Monoestrus (March April May), One cycle per
year
• Interestrus consists of diestrus (60 days) plus
anestrus (a variable time).
• Average duration is 7 months vary due to age,
breed
Interestrous intervals

5. Stage Dur. in days External signs
Proestrus 4-14
(9 days)
Enlarged Vulva w/ bloody
discharge, restlessness, no
courtship w/ male
Estrus 4-21
(10 days)
Clear to pink vulva discharge,
female turns hindquarters
towards him, raises pelvic
region, waves tail, male
acceptance and courtship
Diestrus 60 Vulva shrinks, no discharge,
non-acceptance of male,
terminates with parturation
Anestrus 100 + Inactive ovaries, no vulva
discharge, low steroids
Canine Estrous Cycle

6. Proestrus
9 days
Estrus
9 days
Pregnancy/Diestrus
60 days
Anestrus
90 days

8. Changes During Estrus of Bitch
-8 -4 0 +4 +8 +12
Proestrus Estrus
Aggressive
towards Male
Passive Provides sexual posturing
to male for copulation
Bloody discharge
from vulva Copulation
Vulva Swollen and Enlarged
Indicates Day of
Peak in LH

9. S

10. Ova is released prior to
the formation of first polar
body (primary oocyte)
Sperm longevity is uptil 6
days
2 Cell embryo stage vary
from 2-7 days
Hatching 13-15 days
Fertilizing ability of sperm in
female tract is 9-11 days

11. GnRH Ovulation
Corpora lutea
Progesterone
Ovulation-Estrus
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
LH
Estrogen
Proestrus
1 92 3 54 6 7 8
Estrus
1 92 3 54 6 7 8
LHSurge
Progesterone initial
rise starts with LH
peak and rises
during estrus (not
diestrus)
Ovulationover24hours

12. Vaginal Epithelial Cells
• Parabasal cells
round, small, large
distinct nucleus
• Superficial Intermediate
borders irregular,
folded
• Superficial (cornified,
anucleated) largest cell,
nuclei faded or absent

13. Early proestrus with a mixture of nondegenerate
neutrophils; parabasal, intermediate, and superficial
epithelial cells, erythrocytes, and mucus (Wright-
Leishman stain).

14. Estrus characterized by superficial cells that are
keratinized, largely anucleate, and have angular,
folded cell margins (Wright-Leishman stain).
Greater than 90% of the cells are cornified.
Most of the cells are usually anuclear cells.

15. Diestrus characterized by a decrease in superficial cells,
increase in smaller intermediate cells, and presence of
neutrophils. Cytologically, diestrus may appear similar to
early proestrus (Wright-Leishman stain).

16. Copulation in Dogs
The male and female
remain “tied”
together because the
bulbus glandis of the penis
remains engorged with
blood after the turn.

17. Ejaculation:
Semen Characteristics:
Three Fractions:
Characteristic Volume
(sperm rich fraction) occurs with 80
seconds.
Tie can last 5 to 30 minutes.
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

18. Pregnancy
• 63 days (58-68)
– Range due to dating from breeding not
fertilization
• Hormonal Changes
– Similar to not mated
– Progesterone maintained higher
– CL required to maintain pregnancy
• No placental progesterone
– Placental relaxin
– Drop in progesterone triggers parturition
• Detection
– Adominal palpation at 3 - 4 weeks
– Ultrasound after day 16

20. Canine Pregnancy
(days relative to LH surge)
• Ovulation (day 2)
• Fertilization in the oviduct (day 3 – 8)
• Maturation of ova (day 5)
• 4- 8 cell embryo (bred early and late) in
oviduct (day 9)
• Uterine horns (day 12)
• Migration (day 13-17)
• Implantation (day 22)
• Palpation (day 25-35)

21. Canine Pregnancy Contd.
(days relative to LH surge)
• X-rays of skull and spine (day 46)
• Beginning of progesterone decline and
nesting behavior (day 62)
• Decline of progesterone to below 2
ng/ml (day 64)
• Decline of body temp by 2.5 degree C
(day 64)
• Parturition (day 65)

22. Pseudopregnancy
• Each time a bitch enters estrus she is
designed to become pregnant, so she goes
into a luteal 'pseudopregnancy’
• Progesterone concentrations remain
elevated
• Female will have nest building, mothering
behavior adopting inanimate objects
• Enlarged mammary glands and lactation

23. Parturition
First Stage of Labor
• Visible straining of bitch in the sitting position
• Placental membrane will break and there will be
fluid discharge from vulva.
• Membrane will rupture spontaneously or through
licking of dam.
Second State of Labor
• Averages 4 hours but can last 6-12 hours
• Period in which the cervix dilates
• Bitch will be uneasy, refuse food, pant, vomiting and
frequently looking at flank

24. Parturition
Second State of Labor; Contd.
• After the start of labor first fetus cannot be
expected to survive more than 6 hours in the uterus.
• Fetuses should be delivered within 2 hours of
each other.
• Usually interval between puppies is about 30
minutes.
Third Stage of Labor
•Passage of fetal membranes should take 5
to 15 minutes.

25. Parturition
Preparation for Parturition
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.
Thanks