Principles of pregnancy diagnosis Flashcards
Why is the absence of oestrus not always a reliable pregnancy indicator?
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
What are the key approaches to diagnosing pregnancy?
Absence of oestrus after mating (except in bitches)
Protein/endocrinological changes
Detection of foetus or foetal membranes
Physical changes in the dam (e.g. enlargement of uterus uterine artery)
Detection of maternal changes secondary to endocrinological changes (e.g. absence of oestrus, change in cervical mucus, vaginal wall thinning)
What hormonal markers indicate pregnancy?
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)
How can the foetus or foetal membranes be detected?
Ultrasound examination
Rectal palpation
Radiographic examination
Abdominal palpation
Label the mare hormonal profile
What are the major hormonal changes during pregnancy in mares?
- Early pregnancy: Primary corpus luteum (CL) produces progesterone
- Day 35-40: Endometrial cups form, secreting eCG, which stimulates secondary CLs
- Day 100-120: Placenta takes over progesterone production, leading to decline in CL-derived progesterone
- Late pregnancy: Oestrogen increases, supporting fetal growth & placental development
What is the earliest day at which you can detect pregnancy in mare via ultrasound?
day 12
What is the earliest day at which you can detect pregnancy in bitch via ultrasound?
Day 18 but more commonly from day 28
How does the oestrous cycle differ in pregnant and non-pregnant bitches?
There is no difference in progesterone profile between pregnant & non-pregnant bitches, making progesterone unreliable marker for pregnancy
What is the most reliable hormonal indicator of pregnancy in bitches?
Relaxin, which increases significantly in pregnancy & can be detected from day 25 post-mating
From what day can you see foetal mineralisation in bitches via radiography?
day 45
How is Pregnancy diagnosed in cows?
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)
What is the best PD method in cows for:
1. Early testing
2. Positive diagnosis accuracy
3. Negative diagnosis accuracy
- Milk progesterone
- Transrectal ultrasound
- Transrectal ultrasound & rectal palpation
How is Pregnancy diagnosed in ewes?
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
How is Pregnancy diagnosed in sows?
Failure to return to oestrus (day 18-24)
Transabdominal B-mode ultrasound (day 20)
- Detection of fluid filled uterine horn
- Later detection of embryo
How is Pregnancy diagnosed in mares?
Transrectal ultrasound (day 12)
Transrectal palpation (day 21)
Plasma eCG (day 60-120)
Transrectal fetal ballottement (day 80)
How is Pregnancy diagnosed in bitches & queens?
Transabdominal ultrasound (day 25)
Plasma relaxin (day 25)
How does pregnancy diagnosis protocol vary in production systems?
Cows: Ultrasound 4 weeks post-AI for early detection
Mares: Stud management requires ultrasound at days 14, 21 & 35 post-mating
