Lecture 24: Reproductive 3 Flashcards
Define embryonic loss
loss after short gestation:
large animals
- 33 - 45 d
small animals
- 20d
typically subclinical
What are 3 common causes of embryonic loss?
non-infectious chromosomal abnormality
or
tritrichomonas fetus
or
campylobacter fetus subsp. venerealis
Define abortion
Expulsion of fetus pre-viability
Define stillbirth
Expulsion of dead viable fetus
Define a non-viable neonate
Expulsion of a live but weak baby
Can diagnostic labs give a definitive diagnosis of fetal loss? Why?
it is not common
because the lab receives variable amounts of fetus and/or placenta with little info on maternal health
- the fetus may be autolyzed or resorbed
- the placenta is not always available and some infection agents only have placental lesions
How to increase the diagnostic rate when submitting a sample to the lab
provide fresh fetus and placenta
identify if it is an outbreak or sporadic
if it is infectious there is a 90% diagnosis rate
What are 2 types of causes of fetal loss? Which is common?
infectious: most common
non-infectious: most common in horses because they have a small placental reserve
List 5 non-infectious causes of fetal loss
anomalys/malformation
nutrition (goiter)
toxicosis (plant)
hyperthermia
environmental stress and trauma
List 6 causes of non-infectious fetal loss that are specific to horses
twinning: not enough resources
- if there is a twin we usually ‘pinch off’ one of them to reduce loss
endometrial fibrosis and reduced villus development
- low communication between mom and fetus
premature placental seperation
body pregnancy
- pregnancy in uterine body
umbilical cord:
- torsion
- too long (>83cm)
What is something to consider when dealing with a fetal loss cause due to an infectious cause
most of the abortative pathogens are zoonotic
use PPE and an N95 mask
List 10 bacterial abortative pathogens. Which are zoonotic
zoonotic
- brucella
-campylobacter
- leptospira
- chlamydia abortus
- coxiella burnetii (Q fever)
- listeria monocytogenes
- salmonella
- yersinia pseudotuberculosis
not zoonotic
- mycoplasma
- ureaplasma
List 2 types of viruses that cause fetal loss. What are some examples of each virus type
herpes
- BHV1
- EHV 1
- caprine HV1
- suid HV1
pestivirus
- cow: BVD
- sheep: borders sz
- pig: CSF
What are the gross lesions associated with herpes virus
multifocal 1-2mm white foci of necrosis on the liver but also other organs like lung/kidney/adrenal/brain
What are he histologic findings associated with herpes virus infection
eosinophilic intranuclear inclusion
acute lytic necrosis
What are the clinical consequences of pestivirus infection
fetal death or persistent infection or malformations like cerebellar hypoplasia
the outcome will depend on age/viral strain/fetal immune system
List 3 protozoal agents that cause fetal loss. Which are zoonotic
zoonotic: toxoplasma gondii
neospora caninum
sarcocystis
If you suspect placentitis what are the top 3 tissues you should culture
fetal lung, stomach/abomasal contents
placenta
What are the routes of infectious associated with fetal loss? Which are most common
ascending infection
- common in horses (loose cervix)
hematogenous
- common in ruminants
Describe the steps of a pathogen colonizing the fetus
- form placentitis
- penetrate the chorioallantois
- can cause skin lesion - contaminate amniotic fluid
- fetus ingest or inhale - may colonize umbilical vessel
- infect fetal liver
the pathogenesis indicates which tissues would be good to culture to find the bacteria
- fetal liver/lung/stomach
- placenta
List the 6 steps to the diagnostic process when assessing fetal loss
- examine the placenta
- fetal exam
- estimate age of fetus
- determine state of preservation when expelled
- classify death
- fetal necropsy
What gross lesions are commonly found on the placenta due to viral infection
no gross lesions on placenta
List 3 important non-lesions that can be found on the placenta. Which species are they common in?
amniotic plaques: all species
adventitial placentation: cattle
hippomane: horse
What are amniotic plaques
foci of squamous epithelium on the internal surface of the amnion
What is adventitial placentation
intercoteledenary placentation
it forms to compensate for a low number of placentomes
List 3 types of placentitis
bacterial placentitis
fungal placentitis
protozoal placentitis
What is the gross appearance of bacterial placentitis and how does it compare to fungal placentitis
there is intercoteledenary and coteledenary placentitis
- exaggerated cotyledonary cupping
- leathery surface
- infarcts
fungal placentitis will be MUCH more severe than bacterial
What is a common causative agent of bacterial placentitis
brucella sp
What is a common causative agent of protozoal placentitis
toxoplasmosis in small ruminants
What are the gross lesions associated with protozoal placentitis
cotyledonary placentitis with pinpoint foci of necrosis
What should you assess if you are looking for placentitis in a horse
look for it closest to the cervical star (the part of the placenta that covers the cervix)
also check for umbilical cord torsion of excessive length
What are 3 general categories of things you should assess when doing an external fetal exam
evidence of stress (meconium staining)
congenital abnormalities
skin lesions
Why is meconium staining commonly seen in fetal loss
intrauterine hypoxia results in meconium release
fetus will also gulp/gasp (due to hypoxia) resulting in meconium ingestion and/or inhalation
Where is meconium staining commonly located
trachea
lung
skin
abomasum
What are common external gross lesions associated with dystocia as a cause of fetal loss
meconium staining
reduced venous return from the head (if it was sticking out of mom for a while)
- congestion/edema/hemorrhage
What are 2 types of causes of congenital abnormalities leading to fetal loss? Provide a common example
breed associated
unknown (genetic/teratogen/nutrition/virus)
ex. skunk cabbage/veratum californicum in ewes ingested at d14 of gestation
Provide 3 examples of skin lesions that are associated with fetal loss
myotic: fetal dermatitis and hyperkeratosis
- raised white plaques on the shoulder and head
BVD: hypotrichosis
border dz in sheep: abnormal wool/hairy shakers
(BVD/border dz are pestiviruses)
What are 3 ways to verify fetal age?
weight of fetus
fetal characteristics - hair coat/incisors
crown-rump length
- stretch out and tilt head down - measure from behind eyes > sacrum
Why is fetal age important to understand? Provide an example
age at fetal loss can vary depending on the cause
- neospora caninum in cattle cause loss at mid - gestation
Is fetal growth a good way to measure fetal age?
not really
can vary based on maternal nutrition/placental insufficiency/ or fetal disease
List 4 types of fetal preservation states
fresh
autolyzed
mummified
macerated
What type of fetal loss is a ‘fresh’ fetus associated with
chronic stress (fetal stress initiates birth)
parturition initiated and the fetus is expelled immediately
What type of fetal loss is a ‘autolyzed’ fetus associated with
acute death
there is no significant signal to the cow - allow for autolysis
What are the necropsy findings characteristic to an autolyzed fetus
homogenously pink, gelatinous, with serosanguinous fluid
What are 3 common causes of fetus autolysis
virus
septicemia
protozoa
What type of fetal loss is a ‘mummified’ fetus associated with
acute death
no signal to cow for parturition
closed cervix and no bacteria result in dehydration of the fetus
What is the characteristic gross findings of a mummified fetus
firm, dark brown/black
What are the common causes of mummification of fetuses
virus
protozoa
non infectious
What are the characteristics of a ‘macerated’ fetus
liquification of the fetus due to bacterial infection (the bacteria may or may not be the cause of death)
What are common causes of fetal maceration
metritis
endometritis
pyometra
toxemia
How to differentiate a stillborn fetus with a live born fetus that died on gross exam?
still borns: no air in the lungs and no hemorrhage
live born: can have hemorrhage and air in lung
Truperella pyogenes causes what type of respiratory tract lesion
hemorrhagic cast in calf trachea
EHV1 causes what type of respiratory tract lesion
fibrin cast in the horse fetus trachea
Why should you always sample the lung on fetal necropsy
because it reflects the amniotic environment
What 2 conditions can the fetal liver indicate to you on fetal necropsy
viremia or septicemia lesions
What type of lesions does campylobacter infection cause in a fetus? What species is affected? What type of campylobacter?
targetoid areas of necrosis on the liver of small ruminants
C. jejuni or fetus
What are common MSK abnormalities you should watch out for on fetal necropsy? Why are they important?
arthrogryposis (fixed/crooked joints)
spinal column malformation
- torticollis or lordosis
they are caused by CNS malformation
What should you consider if multiple fetuses are submitted from the same place, all with MSK abnormalities
teratogenic cause
- viral: cache valley virus
- plants
What gross lesions might you find in the brain? What are common causes for these lesions?
cerebellar hypoplasia
- virus: panleuk/BVD/CSF
protozoa also target the brain
If on necropsy, the fetuses brain is a liquidy soup is it still useful as a diagnostic sample?
YES
