Group 3- set 3/3 - Pregnancy Complications - revision period COMPLETE **** Flashcards
State the 3 possible types of embryonic loss
early embryonic death
late embryonic death
abortion
Early Embryonic Death: When does this occur?
- What does this mean?
pre-implantation
before maternal recognition of pregnancy
the life of the corpus luteum has not been extended
Early Embryonic Death: What classes as early embryonic death in a cow?
- what percentage of loses are early embryonic in cows?
embryo loss before day 21
75%
Late Embryonic Death: When can this occur? 2
peri-implantation
after the life of the corpus luteum has been extended
Abortion: When does this occur? 2
post-implantation
after organogenesis
When might pseudopregnancy occur following pregnancy loss?
- What happens as a result? 3
- Which species can this occur in?
if the pregnancy loss occurred after maternal recognition of pregnancy
the corpus luteum fails to regress
progesterone is secreted
leading to pseudopregnancy
mare, sow, goat, queen
Pregnancy Loss in Mare: State the 2 types of pregnancy loss in the mare and give dates
type 1 is early embryonic death after maternal recognition of pregnancy so after day 15
type 2 is foetal death after endometrial cup formation at day 36
Pregnancy Loss in Mare - Type 1: What happens after the pregnancy loss?
- How can you treat this?
the corpus luteum will persist, prolonging the luteal phase
prostaglandin
Pregnancy Loss in Mare - Type 2: How long does the Pseudopregnancy last?
- Why can’t you treat this with prostaglandin?
until the demise of the endometrial cups between days 90-150
because the loss occurred after the formation of the endometrial cups which are secreting ECG to increase progesterone production
Pregnancy Loss in Goat: Why might you get pseudopregnancy in the goat after pregnancy loss post maternal recognition of pregnancy? 2
- What phenomenon can happen in goats, making the goat look very pregnant?
- What is this called clinically?
because the corpus luteum will persist
so progesterone will still be produced
the accumulation of sterile secretions into the uterus in the absence of an embryo
hydrometra or cloudburst
Pregnancy Loss in Goats: Why can you get Pseudopregnancy in cyclic non-mated does?
the corpus lutes persists for an unknown reasons
so progesterone will still be produced
Give and explain some causes of embryonic and foetal loss 7
chromosome abnormalities
nutritional deficiencies
environmental factors - climate, stress, pollutants
infectious agents
trauma by rectal palpation during PD
insemination - poor semen quality or given in error during pregnancy
physiological factors like uterine environment or ovulation rate
Why could insemination during pregnancy cause pregnancy loss?
semen contains prostaglandins which could induce luteolysis
Which factor is the most common cause of abortion in Ruminants?
infectious agents
Infectious Agents: What are the 3 main routes for entry of infectious agents during pregnancy?
- What about before pregnancy?
the cervix
the blood
pathogens affecting the corpus luteum
with the sperm
Infectious Agents: Which cervixes can be affected by ascending infections?
both an incompetent cervix and competent cervix
Infectious Agents: How can systemic (in the blood) infectious agents cause abortion?
could affect the endometrium
could affect the placenta
could cross the placenta and affect the foetus
Infectious Agents: Give an example of a pathogen which can affect the corpus luteum
infectious bovine rhinotracheitis
Infectious Agents: State the 4 most common ones
bacterial
viral
parasitic
fungal
Manifestations of Pregnancy loss: What happens following -
- Early Embryonic death
- Death following infection
tissues are normally reabsorbed and animal returns to oestrus
pyometra may follow
Why in cattle might a Pyometra occur following death by infection?
because the corpus luteum persists, so the cervix remains closed and pus can accumulate
Manifestations of Pregnancy loss: What happens following -
- Later gestational loss
expulsion of aborted foetus or foetal mummification
Why might expulsion of aborted foetuses occur following later gestational death, if not all the foetuses are dead?
death of some of the foetuses in the first half of pregnancy may cause lysis of the corpus luteum and immediate expulsion
What is Papyraceous mummification? 3
where foetal fluids and reabsorbed
foetal membranes are shrivelled
and the uterus contracts
What happens with mummification of a foetus in polytocus species?
mummified foetus might be expelled at parturition with no harm to the live foetuses
Which species are more likely to expel aborted foetuses fresh?
- Why? 4
species that are not dependent on the corpus luteum throughout pregnancy
because foetal death leads to cessation of the foetal contribution to the placenta
so placental progesterone declines
and the foetus is expelled in a fresh state
Which species are more likely to expel an aborted foetus in a state of autolysis?
- Why?
species that are dependent on the corpus luteum throughout pregnancy
because there will be a delay between the time of death and lysis of the corpus luteum
Infectious Agents: Does the time of infection have an impact on the effect of the infection?
- Give an example of such an infectious agent for-
- Sow
- Cow
-Ewe
porcine parvovirus
bovine viral diarrhoea virus
border disease virus
What does SMEDI stand for?
- What can it be used to do?
stillbirths
mummification
embryonic death
infertility
to characterise a number of viral infections in the sow
How does SMEDI work? 2
it reflects the different stages of development at the time of infection
the stage at which the sow is infected determines which one of SMEDI will manifest
SMEDI: What is a classical sign of a SMEDI infection? 2
- What is often the cause?
a full term litter consisting of small mummified foetuses ranging up to full grown still born or live weak piglets
it reflects a progressive infection in utero
porcine parvovirus
What type of causes is responsible for the most equine abortion?
non-infectious causes
What is the impact of twins on -
- Mares
- Cows 2
it reduces the surface area for nutrient exchange
it reduces foetal growth and calf birth rate
causes freemartinism in mixed sex pregnancies
Equine Twinning and Pregnancy Failure: Why is it so important that we dont get twins?
- What happens if we do get twins that causes loss?
because the placenta is epitheliochorial so the conceptus is reliant on nutrition from the entire surface area of the endometrium
as the placentas grow they abut each other and the placental interface cannot absorb sufficient nutrients
Equine Twinning: What are the potential outcomes that can happen if twins occur? 3
one foetus may be resorbed at an early stage
or one foetus may be mummified at an early stage
or both twins are aborted in mid to late gestation
Freemartinism: Why does this occur?
placental fusion permits the exchange of foetal cells and foetal hormones between foetuses
the male hormones androgenise the female foetus producing a sterile XX/XY chimeric female
Define Intra-uterine growth restriction
impaired growth and development of the mammalian embryo or its organs during pregnancy
What can cause IUGR?
it can be naturally occurring
or it can be environmentally induced
Give a few examples of environmental factors causing IUGR 4
temperature and stress
insufficiency of the uterus endometrium or placenta
ingestion of toxic substances
maternal nutrient deficiencies
IUGR: A placental insufficiency can be the cause of IUGR.
- What are the different causes of placental insufficiency and how do they lead to placental insufficiency? 4
multiple foetuses causing reduced placental blood flow in ruminants
impaired by uteroplacental blood flow, placental size or surface area
poor placental growth due to over or under nutrition
gynaecological immaturity where the mother and foetus compete for nutrition
Schmallenberg Virus: What are its possible effects? 2
- How is it transmitted?
late abortion
birth defects in newborn sheep, cattle and goats
insect vectors
Schmallenberg Virus: Does it cause the same types of deformities in all infected animals?
no the foetal deformities vary depending on when in the pregnancy the infection occurred
Schmallenberg Virus: Mid-gestation Infection
- What does the virus affect at this stage?
- How would this manifest in the offspring? 3
CNS development
very minimal brain development
permanently flexed joints
surviving animals would have major mobility issues
Schmallenberg Virus: Mass immunity was achieved due to widespread infection in recent years.
- However, why are we expecting to see it re-emerge every 3-5 years?
because ewes are being replaced at a rate of 20-25% per year, so naive flocks are generated every 4 years
Schmallenberg Virus: What other disease should be considered in malformed calves and lambs?
blue tongue
Chlamydial Abortion: This is the main cause of Ovine abortion in UK
- When in the pregnancy would the abortion occur?
- Why is this?
in the last 3 weeks of pregnancy
due to placental damage from day 90 from colonised bacteria and inflammation
Chlamydial Abortion: Describe some of the pathological features 2
thickened areas of tissue between the cotyledons on the placenta
brown exudate over the surface of the placenta
Chlamydial Abortion: Why is it important to isolate infected animals?
because the organisms are present in large numbers in abortion products so must prevent contamination of the environment and other ewes
Toxoplasma Gondii: Which species does this cause pregnancy loss in?
- What type of pathogen is it?
- What type of host are the sheep?
- How do sheep become infected?
sheep
intracellular protozoan
intermediate hosts
ingestion of oocysts in food and water
Toxoplasma Gondii: How is it similar to schmallenberg?
- What effect would it have in early pregnancy compared to late pregnancy?
- What pathology does it cause?
the time of infection determines its impact on the foetus
much greater impact in early pregnancy than late pregnancy
lesions in the brain, liver and kidneys of aborted foetuses
Toxoplasma Gondii: Describe some of the pathological features that allow you to identify this as the infective agent
dark red placental cotyledons with white speckles of necrosis
Campylobacter: When would abortion occur?
- What would the birth of a live infected lamb look like?
- Why can it spread so rapidly between animals?
in the last 6 weeks of gestation
weak lamb
large number of organisms in the aborted materials
Non-infectious Pregnancy Loss in Cow: State 4 possible causes
nutrition
stress
timing of insemination
conception too soon after calving
Non-infectious Pregnancy Loss in Cow:
- Give examples of different nutritional problems leading to pregnancy loss 3
- Give examples of causes of stress 2
vitamin A deficiency
negative energy balance
high intake of rumen degradable protein
high temperature
high humidity
Non-infectious Pregnancy Loss in Cow:
- How can timing of insemination cause pregnancy loss?
- Why can conception too soon after calving result in pregnancy loss?
if it is performed too late in the oestrus period the ovum may have aged causing embryonic death
due to the poor uterine environment
Non-infectious Pregnancy Loss in Ewe:
- give one risk factor for embryonic death
multiple conceptions
Non-infectious Pregnancy Loss in Sow:
- What are the possible types of reasons for pregnancy loss in sow? 2
- Why might a sow fail to establish a pregnancy?
- What is the most common reason for failure of an established pregnancy?
failure to establish a pregnancy
failure of an established pregnancy
unattached conceptus is susceptible to damage due to long pre-implantation period
break down in maternal recognition
infection
Risk factors of pregnancy loss in Sow:
- Give and describe them
ovulation rate - the higher the ovulation rate the lower the chance of embryo survival
competition for uterine space when there are more than 5 foetuses
nutrition - high energy levels post service reduces embryo survival
stress due to temperature or management
