Breeding & pregnancy diagnosis

Question 1

Why is the absence of oestrus not always a reliable pregnancy indicator?

Answer 1

Some animals may not return to oestrus due to dioestrus ovulation

Dams with young offspring may suppress oestrous signs due to protective behaviour

Oestrus-like signs can sometimes occur during pregnancy, esp in later stages

Question 2

What are the key approaches to diagnosing pregnancy?

Answer 2

Absence of oestrus after mating (except in bitches)

Protein/endocrinological changes

Detection of fetus or fetal membranes

Physical changes in the dam (e.g. uterine enlargement & uterine artery)

Detection of maternal changes secondary to endocrinological changes (e.g. absence of oestrus, change in cervical mucus, vaginal wall thinning)

Question 3

What hormonal markers indicate pregnancy?

Answer 3

Pregnancy-associated glycoproteins (species-specific)

Progesterone (sustained levels post-mating)

Placental oestrogens (measurable in urine or blood)

Relaxin (used in bitches & queens)

Equine chorionic gonadotropin (eCG) (mares)

Question 4

How can the fetus or fetal membranes be detected?

Answer 4

Ultrasound examination
Rectal palpation
Radiographic examination
Abdominal palpation

Question 5

Label the mare hormonal profile

Answer 5

Question 6

What are the major hormonal changes during pregnancy in mares?

Answer 6

1. Early pregnancy: Primary corpus luteum (CL) produces progesterone
2. Day 35-40: Endometrial cups form, secreting eCG, which stimulates secondary CLs
3. Day 100-120: Placenta takes over progesterone production, leading to decline in CL-derived progesterone
4. Late pregnancy: Oestrogen increases, supporting fetal growth & placental development

Question 7

What is the earliest day at which you can detect pregnancy in mare via ultrasound?

Answer 7

Day 12

Question 8

What is the earliest day at which you can detect pregnancy in bitch via ultrasound?

Answer 8

Day 18 but more commonly from day 28

Question 9

How does the oestrous cycle differ in pregnant and non-pregnant bitches?

Answer 9

There is no difference in progesterone profile between pregnant & non-pregnant bitches, making progesterone unreliable marker for pregnancy

Question 10

What is the most reliable hormonal indicator of pregnancy in bitches? When can it be detected?

Answer 10

Relaxin, which increases significantly in pregnancy & can be detected from day 25 post-mating

Question 11

From what day can you see fetal mineralisation in bitches via radiography?

Answer 11

Day 45

Question 12

How is Pregnancy diagnosed in cows?

Including days

Answer 12

Failure to return to oestrus (day 18-24)

Transrectal ultrasound (day 28)

Transrectal palpation (day 35)

Membrane slip (palpation) (day 35-90)

Ballottement of fetus (day 50)

Transrectal palpation of caruncles/cotyledons (day 80)

Transrectal uterine artery fremitus (day 105-210)

Question 13

What is the best PD method in cows for:
1. Early testing
2. Positive diagnosis accuracy
3. Negative diagnosis accuracy

Answer 13

1. Milk progesterone
2. Transrectal ultrasound
3. Transrectal ultrasound & rectal palpation

Question 14

How is Pregnancy diagnosed in ewes?

include days

Answer 14

Failure to be raddled (day 16-19)

Transabdominal ultrasound (day 30)
- Detection of fluid filled uterine horn
- Later detection of cotyledons/caruncles
- Slightly later examination increases accuracy & enables determination of no. of fetuses

Question 15

How is Pregnancy diagnosed in sows?

Answer 15

Failure to return to oestrus (day 18-24)

Transabdominal B-mode ultrasound (day 20)
- Detection of fluid filled uterine horn
- Later detection of embryo

Question 16

How is Pregnancy diagnosed in mares?

Include days

Answer 16

Transrectal ultrasound (day 12)

Transrectal palpation (day 21)

Plasma eCG (day 60-120)

Transrectal fetal ballottement (day 80)

Question 17

How is Pregnancy diagnosed in bitches & queens?

Answer 17

Transabdominal ultrasound (day 25)

Plasma relaxin (day 25)

Question 18

How does pregnancy diagnosis protocol vary in production systems?

Answer 18

Cows: Ultrasound 4 weeks post-AI for early detection

Mares: Stud management requires ultrasound at days 14, 21 & 35 post-mating

Question 19

What is oestrus? What are the key signs? What is the timing?

Answer 19

Oestrus: Period when female is sexually receptive to male

Key signs: Pro-oestrus precedes it; classic sign is standing to be mated

Timing: Varies by species in length, intensity & ovulation timing

Question 20

When does oestrus occur in females?

Answer 20

During late follicular phase, driven by rising oestradiol

Question 21

To what species does this hormonal profile belong?

Answer 21

Ewe, cow, sow

Question 22

To what species does this hormonal profile belong?

Answer 22

Mare

Question 23

To what species does this hormonal profile belong?

Answer 23

Bitch

Question 24

How does the timing of ovulation vary across species?

Answer 24

Ewe, Cow, Sow: Ovulation occurs after oestrus ends

Mare: Ovulation occurs towards end of oestrus

Bitch: Ovulation occurs several days after oestrus begins

Question 25

What factors affect the optimal time to mate?

Answer 25

Male factors: - High-value males may be introduced at a specific time - Controlled mating/artificial insemination requires oestrus monitoring Female factors: - Requires pre-ovulatory follicle growth - Oestrus doesn't always predict ovulation timing - Oocytes are short-lived (<1 day) in most species (days bitch)

Question 26

What is the difference between the fertilisation period and the fertile period?

Answer 26

Fertilisation period: When oocytes are available for fertilisation (hours to days depending on species) Fertile period: broader window where mating can result in pregnancy

Question 27

What tools are used to determine the best breeding time?

Answer 27

Hormone monitoring (progesterone, LH, oestradiol, GnRH) Ultrasound to track ovarian structures Rectal palpation (e.g. in cows, mares) Vulval softening & vaginal cytology (dogs) Pharmacological induction of ovulation

Question 28

How does progesterone indicate oestrus and ovulation timing?

Answer 28

Decreases after luteolysis, marking start of follicular phase Must be low for oestrus to occur In dogs, rising progesterone level indicates luteinisation, meaning ovulation is imminent

Question 29

What is the role of oestradiol in predicting ovulation?

Answer 29

Elevated during follicular phase, often mirroring oestrus (Only used in research setting)

Question 30

What is the role of GnRH in ovulation?

Answer 30

GnRH surge triggers LH release, leading to ovulation Has a short-lived effect No commercial kits available for routine clinical use

Question 31

How is LH used to predict ovulation?

Answer 31

LH surge directly triggers ovulation Tightly regulated time frame from surge to ovulation Commercial kits available for cats & dogs Frequent sampling required, optimal window day 4-7 post-surge in dogs

Question 32

How does the reproductive tract feel under oestrogen dominance (during oestrus) in mare and cow?

Answer 32

Mare: - Broad & soft cervix - Large, oedematous (soft) uterus Cow: - Narrow & tense cervix - Oedematous uterus with increased tone

Question 33

How does the reproductive tract feel under progesterone dominance in mare and cow?

Answer 33

Mare: - Hard & narrow cervix - Small uterus with increased tone Cow: - Flaccid and soft cervix - Flaccid uterus with reduced tone

Question 34

Why is it important to check for the corpus luteum (CL) on ultrasound?

Answer 34

Active CL means high progesterone, preventing ovulation If regressing, it becomes smaller with increased echogenicity

Question 35

What are the typical follicular sizes for ovulation in different species?

Answer 35

Cows: Follicle must be ≥10 mm, typically 16-20 mm. (>20 mm may indicate pathology) Mares: Follicle typically reaches 30-50 mm before ovulation Ovulation when follicle stops growing

Question 36

How does follicular morphology change before ovulation?

Answer 36

Follicle loses turgidity & becomes irregular in shape Mare-specific: follicular wall thickens (luteinisation) before ovulation In horses & high-value cattle, precise monitoring helps time breeding optimally

Question 37

Why is vaginal cytology used in dogs?

Answer 37

Helps determine oestrous stage by analysing vaginal epithelial & blood cells Used alongside progesterone testing to optimise mating time

Question 38

How do vaginal cells change during the oestrous cycle in the bitch?

Answer 38

Proestrus: - Increasing epithelial layers under oestrogen influence - RBCs present → responsible for bloody vaginal discharge Oestrus: - Large cornified (anuclear) cells appear - Peak cornification = optimal mating time Metoestrus: - Influx of neutrophils → indicates ovulation has passed & it's too late for mating

Question 39

How can ovulation be induced for controlled breeding?

Answer 39

GnRH: Induces LH surge → ovulation within ~1 day hCG: Mimics LH, directly triggering ovulation OvSynch protocol (cattle): Synchronises ovulation for timed AI

Question 40

When is the optimal time for mating in the bitch?

Answer 40

Peak fertility occurs 1d before to 5-6 days after LH surge Best determined by: - Plasma progesterone measurement (rises post-LH surge) - Vaginal cytology (≥80% cornified cells) - Serial LH measurement (daily testing needed)

Question 41

What phase of the oestrus cycle is this?

Answer 41

Anoestrus: Small parabasal cells, majority of cells are circular, occasional neutrophils

Question 42

What phase of the oestrus cycle is this?

Answer 42

Proestrus: Small intermediate cells, majority of cells are irregular in shape, large number of RBCs, occasional neutrophils

Question 43

What phase of the oestrus cycle is this?

Answer 43

Oestrus: Large intermediate and anuclear cornified cells, irregular shaped cells, some RBCs, no neutrophils

Question 44

What phase of the oestrus cycle is this?

Answer 44

Metoestrus: Return of neutrophils, fewer cornified cells

Question 45

How do plasma progesterone and anuclear cells change around the LH surge in bitches?

Answer 45

Before LH surge: - Low progesterone, increasing anuclear (cornified) cells. At ovulation (~2 days post-LH surge): - Progesterone rises sharply due to luteinisation - Anuclear cells peak, indicating optimal mating time After ovulation (~7 days post-LH surge): - Progesterone remains high, supporting pregnancy - Cornified cells decline, neutrophils may appear (metoestrus)

Question 46

How do oestrogen and progesterone affect the vaginal epithelium?

Answer 46

Oestrogen (Proestrus & Early Oestrus): - Thickens vaginal mucosa → keratinised squamous epithelium (protects against mating trauma) - Increases oedema, causing red to pink/white mucosa - Leakage of RBCs (serosanguinous discharge) seen in early proestrus Progesterone (Post-LH Surge & Luteal Phase): - Reduces oedema - Causes mucosal shrinkage & wrinkling - Leads to shedding of epithelial surface at end of fertile period