AMHP Pregnancy & Parturition Flashcards
Pregnancy Diagnosis: Bitch (also cat)
- Abdominal Palpation • 21-28 days
- Small ‘golf balls’
- Not very reliable – false positives and false negatives (fat or tense bitches)
- Ultrasonography
- Identify vesicles from 17 days
- Generally done 21-30 days
- Differentiate pregnancy from pyometra
- Litter number less accurate with large litters and later in gestation
- Radiography
- Best from 47 days when foetal skeletons are obvious
- Litter number less accurate with large litters and later in gestation
- Relaxin assay
- (NB not progesterone as that is high in all bitches post oestrus)
Pregnancy diagnosis in production animals
• Important for management of the flock/herd
• Detection and management of non-pregnant animals is particularly
important
• Minimise ‘empty days’ (pigs, cows), ‘yeld’ or barren ewes • Treatment
• Investigation • Culling
Pregnancy Diagnosis: Sheep (1) Service and non-return to oestrus
- Use of raddle to detect non-return to oestrus
- Benefits:
- Early indication of fertility issues
- Tup is working
- Ewes are cycling
- Group and manage according to expected lambing date
- Either: harness and coloured crayon block • Check harness fit regularly
- Change crayon colour every 17 days
- start with light colour before darker ones
- Or: smear on raddle powder mixed with veg oil • Re-apply every few days
• Ultrasound scanning • Usually between 45-90 days of pregnancy • Benefits: • Detect fertility problem early • Identify and cull barren ewes • Manage ewes based on foetal numbers • Nutrition • Plan for artificial rearing if high % of multiple pregnancies
Pregnancy diagnosis: Pigs
• Return to oestrus (18-22 days) – not pregnant • Ultrasound scanning 21-25 days post oestrus
Pregnancy Diagnosis: Cattle (1)
Non-return to oestrus • But ~20% of cows thought to be pregnant are actually not • Observation of oestrus • Cows in oestrus are frequently mounted by other cows • Tail-paint • Rubbed off when mounted by another cow • e.g. KAMAR HeatmountTM Detector • Internal chamber ruptured when mounted • releases dye which shows as a colour change
Pregnancy Diagnosis: Cattle (2)
• Milk progesterone
• 24 days after service
• Single sample:
• Non-pregnancy: >95% of cows with low progesterone are not pregnant
• High sensitivity
• Pregnancy: 20-25% of high progesterone are actually not pregnant (false
positive) – similar to non-return rates • Low specificity
• Pregnancy-associatedglycoproteins
• From 28 days after service
• Detects foetal glycoproteins in blood or milk
• Accurate except when recent abortion or foetal loss • Relatively expensive (especially blood test)
- Detect foetus, fluid and foetal membranes, and ovarian structures
- Rectal palpation
- From20daysbutgenerally35days
- Noexpensiveequipmentorpowersupply
- Quickandconvenientforsmallnumbers,andlatepregnancies
- Ultrasound
- From26days,butgenerallydoneat40days.
- Expensiveequipment,andpowersupplyneeded • Set-uptimelonger,timetoexaminesimilar
- Quicker for large numbers of cows
- Calvescanbeagedmoreaccurately
- Experienced vet: both methods diagnose >95% of empty and pregnant cows
Pregnancy Diagnosis: Horse (1)
Several methods used: • Return to oestrus • Palpation per rectum • Ultrasound scanning per rectum (day 14) • Repeated at later date to check foetal loss not occurred
Hormonal blood tests:
• Progesterone (P4): 14 – 45 days
• eCG/PMSG:fromday45-100
• Oestrone sulphate: from day 90 until term presence of live foal, can test in mare urine
• Changes in weight / shape • particularly in last trimester
Pregnancy duration
Bitch 63 days (58-68) • Cat 63-67 days (61-72) • Sow 115 days • Sheep 143-147 days (144-152) • Cow 283 days (279-287) • Mare 330-345 (320-362) • Donkey 11-141⁄2 months • Mouse 20 days • Elephant 640-660 days (21 months)
Preparation for parturition
- In late gestation, change to oestrogen being dominant hormone (not progesterone)
- Promotesdevelopmentofcontractileproteinsinsmoothmusclecellsoftheuterus
- Musclesandligamentsofthebirthcanalrelax
- Vulva swells
- Mucusdischargemaybepresent
- Tailheadmusclesmayrelaxsotailappearslowerordepressed
- Mammary glands enlarge and may secrete a milky material (‘waxing up’)
- Animal may
- becomerestless
- seekseclusion
- Urinatefrequently
- Nestbuilding(sow,bitch,queen)
Triggers for normal parturition
• Initiation of parturition is under foetal control
• FoetaladrenalcortexbecomesmoresensitivetoACTHfromthefoetaladenohypophysis(anterior
pituitary gland)
• ↑ Foetal adrenal cortical glucocorticoids
• Affectplacentaandmaternaluterus
• + ↑ placenta oestrogen
• ↑PGF2a
• → luteolysis of corpus luteum (cow and sow)
• → stimulates contraction of uterine smooth muscle
• → moves foetus into birth canal
• → promotes relaxation/softening and dilation of cervix
• Foetusinbirthcanalstimulatesoxytocinreleasefromneurohypophysis(posteriorpituitarygland)
• ↑ oxytocin → enhances uterine contractions and promotes delivery
Physiology of Parturition
Increased in Cortisol, Oestrogen, PGF 2, Oxytocin
Three Stages of Labour
- Stage 1 (described previously)
- Uterine contractions gradually force the foetus and foetal membranes to the cervix
- Cow and ewe2-6hrs; sow2-12hours, mare 1-4hours (but can be delayed if watched)
Stage 2 delivery of the foetus
• Passage of the foetus through the cervix along with rupture of the ‘water bags’
• Initiates abdominal straining/contractions
• Variable time(e.g.foal15-30minutes)
Stage 3 delivery of the placenta
• Within a few hours (delay requires intervention and treatment)
Foetal position
- Single foetus:
- Normal is anterior presentation (diving position)
- In cattle, posterior presentation is common and also considered ‘normal’
- Litters:
- Pigs, bitches, cats:
- Anteriorandposteriorareequallycommonandnotproblematic
- Sheep:
- Firstlambusuallyanteriorpresentation
- Otherpositions,andsimultaneouspresentationofmorethanonelamb–problematic
Stage one of parturition in the horse
- Uterine contractions
- Dilation of cervix
- Restless behaviour, panting, pacing, off feed • Lasts1–4hrs
Stage three of parturition in the horse
• Expulsion of placenta • Completed within 3 hrs of end of stage 2 • Retention of membranes for more than 10 hrs requires veterinary attention
Foaling Problems
• Dystocia (difficult birth) can prolong or even halt parturition: • Feto-maternaldisproportion • Malpresentation • Fetal “monsters” • Uterine inertia • Uterine torsion • Uterine rupture In the mare dystocia is very serious and life-threatening
- Force of contractions means foal can die very soon if becomes stuck or is malpresented
- Foals have long limbs – can be difficult to reposition
- Can correct dystocia by:
- Manual manipulation per vaginum
- Caesarean section
- Oxytocin (uterine inertia only)
- Foal can cause perineal lacerations and rupture rectum
Mare Post-partum Problems
• Common post-partum mare problems: • Perineal or vaginal lacerations • Retained placenta • Retained foetus • Uterine prolapse • Uterine haemorrhage • Metritis • Mastitis
Calving
• Similar to foaling, but more interventions required
• However, cow and calf are often more resilient to delay and dystocia
• After correcting malpresentation, and in cases of maternal fatigue or uterine inertia
• Common to use a calving jack to aid delivery
Calving Jack
Farrowing
- Pigs(andotherlitter-bearing animals) require fewer interventions than those species that give birth to one large offspring
- Signs:
- reduced appetite
- Chewing on bedding
- Failure to settle
- Pigletsbornupto40-45minutes apart – if longer, may need intervention
Pigs – farrowing problems
- Farrowing problems • Uterine inertia
- Large foetus blocking cervix
- Small gilt
- Malpresentation
- Two foetuses presenting simultaneously • Dead foetus(es)
- Indications for Caesarian Section
- Uterine inertia
- “Out of Reach”
- Secondary to Dystocia, foetal oversize, malpresentation, etc
Lambing
• Ewes produce 1-4 lambs (varies with breed)
• Ewes may be lambed outdoors or indoors
• Most ewes deliver without assistance
• Some will require intervention by a
skilled stock-person
• Care before and after lambing is needed by all ewes and lambs
• Many sheep farms employ additional labour at lambing time
• Vet students are commonly employed in the Easter Vacation
Normal lambing behaviour
- First Stage Labour
- Ewe in first stage labour separates from main group.
- Abdominal contractions start, lasting 15-30 seconds
- Initially at 15 minute intervals, increasing to 2-3 minutes apart
- Straining becomes more frequent
- String of mucus may be seen at vulva
- Water bag (allanto-chorion) appears (if it bursts it may go unnoticed)
- Faster process in older animals than first lambers • Disturbance may delay progress
Normal lambing: Second stage labour
• Second stage typically takes about an hour
• Rupture of allanto-chorion • Rush of fluid
• Amnion and foetus are presented into the birth canal
• Powerful contractions every couple of minutes
• Parts of the lamb may be seen protruding from
the vulva
• Lamb usually delivered soon after
• After delivery, ewe should immediately lick and clean the lamb
• Multiple lambs: next follows within minutes or up to an hour later
Normal lambing: Third Stage Labour
- Expulsion of foetal membranes (Placenta)
- Usually within 2-3 hours of delivery of the last lamb
- If not delivered within three hours, should be investigated
