Pregnancy failure/problems Flashcards
What is conception failure?
- not getting pregnant
What is resorption?
- loss of the embryo
What is abortion?
- loss and expulsion of the foetus
What is stillbirth?
- expulsion at term but dead foetus
Causes of conception failure in the bitch
- inappropriate timing of mating
- male factor infertility
- abnormal mating
- mating induced endometritis (a consequence of CEH)
- abnormal uterine environment (a consequence of CEH)
Causes of conception failure in the queen
- inadequate mating, inappropriate time
- male factor infertility
- abnormal mating
- abnormal uterine environment (less common as lower exposure to progesterone than in bitches as most cycles are anovulatory)
What can bitches with CEH develop?
- mating-induced endometritis
Mating-induced endometritis - aetiology
Assumed to be similar to that seen in the mare
- commensal bacteria enter the uterus at the time of mating
- bacteria are rapidly cleared by immune response and uterine contractions
– if there is an abnormal uterus (i.e. CEH) or a poor uterine response this may allow commensal bacteria to persist -> endometritis / mating-induce endometritis
Mating-induced endometritis - tx
- some bitches respond to post-mating antibiotic
– 5d of potentiated amoxicillin starting on the last day of mating
BUT this should only be considered in properly diagnosed cases of CEH.
How can mating-induced endometritis cause pregnancy failure?
- mating-induced endometritis which doesn’t resolve and persists into the (pregnant) luteal phase may result in pregnancy failure
– these dogs resorb the entire litter in the early luteal phase
Embryonic resorption - spontaneous isolated resorption
- resorption of 1 of the embryos (within continuation of the pregnancy) is seen in 10% of pregnancies
- possibly to reduce abnormal embryos or embryo number
- doesn’t appear to be infectious
Causes of resorption/abortion
- canine herpes virus 1
– general pathogen
– viral recrudescence at subsequent pregnancies - brucella canis: important in most countries and now in UK
- canine parvovirus
- canine adenovirus
- canine distemper virus
What should you do when a bitch aborts/resorbs?
Most cases should be examined assuming an infectious cause
- send unfrozen foetus and membranes for investigation
- collect swabs of discharge for PCR
- collect serum to evaluate rising antibody titre
Canine herpes virus 1 - prevention
- vaccine (Eurican Herpes) is available for bitches and is given 2x during pregnancy to protect the litter
Canine herpes virus 1 - what does it cause?
- venereal pathogen causing vesicular lesions in the genital tract of dogs and bitches
- in bitches it may cause resorption, abortion, stillbirths; depending on when infection occurs
Adults
- inapparent infection (carrier)
- re-activates during periods of stress
- repro problems include: infertility in females (& males?), genital lesions, abortion, placentitis (leading to weak puppies)
Neonates (<3w/o):
- acutely fatal dz
- sudden death
- haemorrhage
- v+/d+
- weight loss and failure to suck (‘fading puppy’)
- constant complaining
- neurological signs
- ocular disorders
Canine herpes virus 1 - prevalence
- appears to be increasingly common but no studies on prevalence in UK
Canine herpes virus 1 - transmission
- can be venereally or via the resp tract
Non-infectious causes of resorption/abortion
- abnormal uterine environment
- foetal abnormalities (likely based on other species but not well investigated in dogs)
- low progesterone (GSD breeds)
– but, progesterone will decline after pregnancy loss, so is the fall of progesterone cause or effect this cause or effect?
– if you use progestogens you may
-> increase the incidence of pyometra
-> result in foetal abnormalities
-> impair or delay parturition
Resorption/abortion in the queen - what to do?
Most cases should be examined assuming an infectious cause
- send unfrozen aborted foetus and membranes for investigation
Resorption/abortion in the queen - causes
Infectious:
- feline leukaemia virus
- feline herpes virus
- feline panleucopaenia virus
- GIP
- chlamydia psittaci
- toxoplasma gondii
Non-infectious
- abnormal uterine environment
- foetal abnormalities
- low progesterone
Management of resorption/abortion
Tx of the dam at the time of resorption/abortion
- isolation
- systemic antimicrobials (for secondary infection)
- ecbolic agents (oxytocin) to aid expulsion
- general/specific nursing care
O may want you to try to stop an abortion but this is unlikely to be successful and if the ongoing abortion is infectious it is not a good idea to give progesterone to close the cervix.
General/specific nursing care:
- expulsed material is likely to be small so obstructive dystocia not likely
- but expulsion may take some time
- bitch may be or become debilitated
- IVFT may be required
- if subsequent metritis develops then more intensive supportive care will be required
- encourage eating, etc
Dystocia - history q’s
- has the dam given birth before: if so where there complications and what were these?
- what has recently been observed in this dam?
- has there been recent vulval discharge?
- have uterine/abdominal contractions been noted and if so, when?
- have any foetal membranes/fluid been expulsed?
- have any foetuses been delivered?
- any other relevant info (inguinal hernia etc)
Normal length of pregnancy in the bitch
- 63 ± 1d from ovulation (but time of mating around ovulation is variable)
- the apparent length of pregnancy can vary from 58-72d
– this is bc there is a large window when mating may result in a pregnancy. e.g. mating slightly before ovulation can still result in pregnancy if sperm survive
Methods of assessing possible dystocia
Clinical hx
- mating 58-72d before onset parturition
63d from ovulation
Decline in plasma progesterone
- 1.5d before onset parturition
Decline in rectal temp
- 24h before onset parturition
- progesterone is thermogenic
Onset of uterine contractions
- 2-4h before onset parturition
Onset of abdominal contractions
- 30-120mins before onset parturition
Dystocia - CE
- BAR or dull?
- clinical parameters
- body condition
- able to stand and walk?
- can any foetal parts be seen at the vulva?
- what is the identify of foetal part?
- is there any vulval discharge and if so what colour is it?
- is there evidence of foetal life?
Dystocia - digital exam
- is the vestibule/vagina dilated?
- what is the state of lubrication of the tract?/
- any foetuses present? are they alive? what is there presentation/position/posture?
- any foetal membranes present? are they intact? are they detached?
- what is the relative size of the birth canal and the likelihood of foetuses being delivered?
- any lacerations present?
Dystocia - endoscopic exam
- is the cervix open?
– can’t
Dystocia - US exam
- are the foetuses alive? what is their size?
- what is the foetal heart rate?
Dystocia - radiographic exam
- number & size of foetuses
- signs of foetal death: change in posture, overlapping skull bones, foetal/uterine gas
Foetal heart rate
- normal
- <150bpm
- <130bpm
- <100bpm
Normal foetal hr at term 170-230bpm
- or at least 4x maternal hr
- transient increases with foetal movement
Foetal hr less than 150bpm
- indicates stress (hypoxia)
- immediate intervention required
Foetal hr less than 130bpm
- poor survival if not delivered within 2-3h
Foetal hr less than 100bpm
- immediate (medical or surgical) intervention to hasten delivery before demise of pups
What is dystocia?
- failure of uterine contractions to push pups into birth canal so doesn’t progress to 2nd stage parturition
What is the most common cause of small animal dystocia?
- almost 3/4 of small animal dystocia cases are maternal
- most common is primary uterine inertia
Dystocia tx
Correction of foetal orientation
- retropulsion, correct position/posture
- traction
Oxytocin admin
- after correction of obstruction
- T1/2 is short
- doses are often too high and cause tetany not coordinated contractions
- 0.04IU/kg is appropriate given q30mins for 3 doses
Calcium admin
- 1.0mg/kg SC of 2.5% solution
Likely outcome of manipulation/medical tx
- successful in 28% of bitches
- successful in 30% of queens
- overall approx 70% ultimately undergo c-section
Likely outcome for all tx
- 6% incidence of foetal death when presented within 5h of onset of 2nd stage
- 14% incidence of foetal death when presented between 5-24h of onset of 2nd stage
