3. approach to pregnancy diagnosis Flashcards
what is the clinical importance of early pregnancy diagnosis
- rapidly identify fertility thus any problems in males and females to acto on it, as often a narrow window to breed
- assist with production system (rebreed or cull, management change)
- it may also satisfy the curiosity of the keeper
when is pseudopregnancy in the mare irrelevent
pregnancy failure/loss
1. occurs between days 1 and 5
- embryo lost whilst in uterine tube
- never knew she was pregnant as no MRP
- normal oestrus cycle
- between days 5 and 15
- no MRP
- normal oestrus cycle unless associated with uterine inflammation
what is pseudopregnancy type 1 in the mare
failure between days 15 and 36
- MRP has occured
- no return to oestrus
- primary CL will persist for normal lifespan for about 40 days then naturally regress
- CL can be lysed by the administration of pgf2a
what is pseudopregnancy type 2 in the mare
failure between day 36 and 140
- endometrial cups have formed –> producing eCG that will maintain the accessory CLs
- no return to oestrus
- accessory CLs will persist for their normal lifespan (150 days)
- CL cannot be lysed by the administration of pgf2a
- as eCG is protecting the CLs from prostaglandin
- wait for cusps to disappear before admin pgf2a
outline approaches to pregnancy diagnosis
explain how progesterone is used to diagnose pregnancy and how false -ves/+ves occur
- no decline in progesterone in blood/milk 21 days from mating (exact date depends on species
- false positivies may be due to progesterone remaining high with no pregnancy (ovarian pathology) for example persistent CL
- false negatives due to confusing animals or poor sample storage
- ideally requires frequent sampling
how are pregnancy recognition factors used to diagnose pregnancy
limited
- IFNT largely stays in uterine lumen, not circulation. few tests that can detect IFNT
- mare: dont know what the signal is
- dog: doesnt need pregnancy recognition hormone so nothing to detect
how are feto-pacental oestrogens used to diagnose pregnancy
later on
- the fet-placental unit produces both progesterone and oestrogens
- oestrogens are often found mid-pregnancy onwards in both plasma and urine
- higher concerntrations of oestrogen mid-pregnancy than in oestrus
- no false positive diagnoses
- pregnancy specific oestrogens
- however ideally you want to detect the pregnancy earlier than this method permits
what other pregnancy specific hormones are used to diagnose pregnancy
relaxin
- produced by CL in some species
- but also produced in placenta (bitch/mare)
- used for PD in bitch and queen (cannot use progesterone in dog)
placental lactogens
- produced by the placenta in several species
- luteotrophic
- commercial tests
discuss rectal palpation for pregnancy diagnosis
- requires systematic appraoch
- look for one horn and travel along to find the other
- look for one being enlarged
- unpregnant will be soft but the pregnant will be notable fluid filled and doughy
- best done in monovular species
- detects ballottment (can just about feel the head as theyll be deep in the abdomen and membrane slip (signs of pregnancy)
what are you looking for in abdominal palpation for PD
- detection of enlarged uterus
- ballottement of the fetus
how do you diagnose pregnancy via ultrasound
2 methods:
- doppler applied transabdominally (less common in animals than human)
- B mode real time via transrectal or transabdominal (pigs, dogs, cats probe cranial to hind limb pointing caudal)
what can you see on ultrasound in the early stages of pregnancy
- detection of conceptus
- normally anechoic structure
- representing yolk sac
- early pregnancy is packed full of fluids
- amnion and allantois fluids as pregnancy moves forward but initially yolk sac
- i.e anechoic in nature as fluid
what is the clinical significance of eultrasound examination for migration of equine conceptus
- careful examination required to ensure the diagnosis of twins enabling remedial action as appropriate
- 2 embryos in image below: one must be popped therefore diagnosis must be made early to allow this to be done
- requires careful palpation as these embryos are migratin at this point and might not be ipsilateral with the CL ovary
what can you see on ultrasound at a slightly later stage of pregnancy
detection of an embryo and heartbeat
what can you see on ultrasound later on in pregnancy
bovine: see spinal cord and ribs. at the top, circles surrounded by anechoic area might be placentomes.
canine: limb bid development
why should you check ovaries while doing a PD ultrasound
demonstrate CLs or other likely confirmatory changes
how do you diagnose pregnancy via radiograph
- possibly detect uterine enlargement
- see mineralisation of the skeleton at the point where mineralisation occurs (depends on gestation length)
- common in dogs to count number of offspring but hard and never definitive
list physical changes associated with pregnancy
- increased appetite
- weight gain
- abdominal enlargement
- relaxation of the perineal tissue
what physical changes are indicative of pregnancy
- auscultation of fetal heart beats
- uterine artery enlargement and change in flow (turbulent buzzing feel called fremitus)
list external secondary changes in pregnancy
- no return to oesturs
- teat and mammary gland enlargement and reddening (not reliable in bitch or cow except first calving, dog will develop whether preg or not)
- secretion of milk in late pregnancy
- waxing up in the last few weeks prior to birth (sticks to bottom of teat)
list internal secondary changes in pregnancy
- cervial mucous: long period of elevated plasma progesterone –> mucus may become very dry and tacky (thick, opaque, pale yellow and rubbery)
- vaginal wall thinning: oestrogen increases layers of vaginal wall, prolonged progesterone = few layers in vaginal epithelium (detected by biopsy)
which methods are most commonly used for pregnancy diagnosis in the cow
blue = common
- failure to return to oestrus is a key marker in cows
- will be presented to vet for difinitive dx
- farmer might test milk
compare pregnancy diagnosis techniques in the cow and their relative levels of accuracy
- milk progesterone is earliest method we can use. pretty good at determining not pregnant, less good at saying yes is pregnant
- rectal palp cant be done reliably until later on
