Pregnancy diagnosis in large animals Flashcards
Why do you need to manage non-pregnant animals? 2
to get them pregnant
to cull them
Why do you need to detect pregnancy? 2
stage of pregnancy - drying off and parturition time predictions
number of foetuses - feeding
What are methods for PD? 3
- Non-return to oestrous in polyoestrous spp
- Hormone measurement and other substances
- Detection of gravid uterus - manual palpation, ultrasound, radiography
- Identification of changes in gross and microscopic structure of genital system related to pregnancy
When is bIFNtau produced by bovine embryo?
From day 13 -> prevents luteolysis of CL
When does embryo loss occur in cows?
Before 21 days - 22%
21-42 days - loss 6%
42 days + = 5%
What time frame is a non-return to oestrous defined as?
18-24 days after service
When can you start accurately PDing with B-mode real time radiography?
from 30 days (because this is when the foetus moves away from uterine wall and is more free/visible in lumen)
When is P4 present in pregnant cow’s plasma and milk?
21-24 days
What are the 2 best ways of PDing cow rectally after 30 days?
- Membrane slip (Chorioallantois, from 33 days)
- Horn size disparity - unilateral cornual enlargement with fluctuation, thin uterine wall from d35
Other than membrane slip and horn size disparity how else can you PD a cow rectally? 5
- Presence of placentomes - from 80 days
- Palpation of foetus - 45-60 days (risk of miscarriage)
- Fremitus (hypertrophy of middle uterine artery from d 85 in broad ligament)
- Palpation of foetus (120 days)
- Oestrone sulphate - in milk/plasma, from d105, better at d120
What care needs to be taken when doing a P4 analysis for PD?
When should you do it?
Low P4 = not pregnant
High P4 = pregnancy or other possibilities (i.e. false positive)
Therefore it is a non-pregnancy test.
Do at d18-24 post oestrous/service
What is used as a preservative for the milk P4 assay?
Potassium dichromate tablet
What sample should you use for a P4 test?
Milk > plasma (milk has a higher concentration)
What are reasons for false positive PD milk P4 results? 7
Luteinised cysts CL persistence Error - ID/labelling Shorter than normal oestrous cycle Incorrect AI timing Inadequate sample mixing Embryo mortality
What type of head is used on a transrectal ultrasound probe? Why?
- 5 MHz and later 5 MHz
i. e. low penetration - uterus is right below the rectal wall
