Reproductive 3 (fetal loss) Flashcards
What is abortion?
The expulsion of the fetus prior to the time of viability
What is early embryonic death (EED)?
Large animals: Death up to 35-45 days post-conception. Small animals: Death up to 20 days post-conception. It often goes unnoticed and there is nothing to submit to the lab.
What is stillbirth?
The expulsion of a dead fetus at the time of viability
What is a non-viable neonate?
The delivery of a live, weak-born animal that dies soon after being born.
True or False: We are often able to determine the cause of fetal loss with diagnostic testing
False, most of the time we can’t determine the cause
When sending samples for diagnostic testing to determine cause of fetal loss, what is important to include?
Placenta because some infectious agents can only be detected by the placental lesions they cause.
What factors can improve your chance of getting a diagnosis of fetal loss?
- Fresh fetus sample 2. Placenta included 3. Infectious cause (more easy to detect) 4. Fetal loss is occurring as an outbreak (not just sporadic abortion)
What is the most common known cause of fetal loss in most species?
Infectious is the most common. This is not the case in horses, which have many non-infectious causes of fetal loss. This is due to their lack of placental reserve.
What are four non-infectious causes of fetal loss that are common in all species?
- Nutritional deficiencies or excesses 2. Toxins (ex. plants) 3. Hyperthermia 4. Environmental stresses (including trauma)
What are five non-infectious causes of fetal loss that are unique to horses?
- Twinning
- Inadequate villus development
- Premature placental separation
- Body pregnancy
- Umbilical cord anomalies
What are the two umbilical cord anomalies common in horses?
- Excessive length (prevents blood flow to fetus) 2. Torsion
What two types of viruses cause fetal loss in multiple species?
- Herpesvirus 2. Pestivirus
Name seven zoonotic bacteria that cause fetal loss.
- Campylobacter spp. 2. Chlamydia abortus 3. Coxiella burnetii 4. Leptospira spp. 5. Listeria monocytogenes 6. Brucella spp. 7. Salmonella spp.
Name one zoonotic protozoa that causes fetal loss.
Toxoplasma gondii
What are the gross lesions of herpesvirus?
White multifocal areas of necrosis
Where do we usually find gross lesions of herpesvirus?
Most commonly on liver but can also affect lung, kidney, adrenal gland, and brain.
What inclusion bodies do we see with herpesvirus?
Eosinophilic intranuclear inclusion bodies
What is a major gross CNS lesion seen with pestiviruses?
Malformations of the CNS (like cerebellar hypoplasia)
This also occurs with parvoviruses like panleukopenia virus in kittens.
What is the most common route of infection leading to placentitis in cows?
Hematogenous spread to the placentome
What is the most common route of infection leading to placentitis in horses?
Ascending infection through the ‘loose’ cervix
Once placentitis is established, what are three ways infection can spread to the fetus?
- The infectious agent can penetrate the amnion to colonize on the skin of the fetus
- The fetus can inhale/ingest infectious agent in contaminated amniotic fluid
- The infectious agent can spread through umbilical vessels to the liver and hematogenously throughout the fetus
What type of placenta do horses and pigs have?
A diffuse placenta
What type of placenta do ruminants have?
A cotyledonary placenta
What type of placenta do cats and dogs have?
A zonary placenta
What does a normal bovine chorioallantois look like?
The cotyledons are dark red to brown and the intercotyldonary areas are thin and transparent
What three incidental findings are commonly mistaken for placentitis?
- Amniotic plaques
- Adventitial placentation
- Hippomanes
What is adventitial placentation?
Inadequate placentomes the body makes to compensate for lack of placental exchange.
What causes should we consider when we find intercotyledonary or cotyledonary placentitis?
Bacterial or fungal
What are three features of mycotic placentitis?
Exaggerated cotyledonary cupping, leathery appearance, and infarction
What does a protozoa-caused placentitis look like grossly?
A cotyledonary placentitis with pinpoint foci of necrosis and mineralization.
In a horse, where is the most severe placentitis located?
At the cervical star
What should a normal horse umbilical cord look like?
The umbilical cord should be < 83 cm in length and have no more than 3-4 twists
What is meconium?
The dark green substance formed from the first feces of fetus
When does meconium appear?
Meconium is released into the amnion when a fetus is distressed from intrauterine hypoxia
What is meconium aspiration?
When a fetus gasps and aspirates the dark green fecal material (meconium) into the lungs before or around the time of birth from the amniotic fluid.
We can see this post-mortem in the trachea.
Meconium staining and aspiration is a sign of fetal ____________
Distress
What does meconium look like histologically?
It is bright yellow and very distinctive!!
What causes cyclopia in lambs?
The ingestion of the plant Veratrum californicum (skunk cabbage) on day 14 of gestation by the mother
What do we see grossly with fetal dermatitis/hyperkeratosis in mycotic infections?
Raised, white, plaques often over the shoulders and head
What are causes of intrauterine growth retardation?
- Inadequate maternal nutrition
- Placental insufficiency
- Fetal disease
Why is it important to determine the state of preservation of a fetus?
It can suggest the type of condition responsible for the abortion
What is the difference between a fresh fetus and mummified and autolyzed fetus?
A fresh fetus is indicative of chronic disease, while a mummified fetus is indicative of viral infection, and an autolyzed fetus is indicative of rapid fetal death.
What is an aborted fresh fetus indicative of?
Chronic disease (often placentitis)
What is an autolyzed aborted fetus indicative of?
A rapid fetal death usually from viremia, septicemia, or protozoal infection
What is a mummified aborted fetus indicative of?
Viral infection (specific virus depends on species)
What are two requirements for a mummified fetus to occur?
Bacteria must be absent and the cervix must remain closed
What disease in pigs can cause piglets of varying developments to become mummified?
SMEDI syndrome (caused by parvovirus or enterovirus)
What is a macerated aborted fetus indicative of?
A bacterial infection
How can you be sure a fetus was born alive or dead?
The lungs will be light pink and inflated if born alive
Why is it dangerous for the mother to have a macerated fetus?
It can make the mother very sick with endometritis, metritis, pyometra, or toxemia
What type of lesion is typical of Campylobacter infections in small ruminants?
Targetoid hepatic necrosis
If you see arthrogryposis in a fetus, what two agents are likely behind it?
Teratogenic viruses or toxins
What is the most important fetal organ to look at grossly and why?
The lungs because they are reflective of the amniotic environment
What type of fetal pneumonia is indicative of bacterial placentitis?
Fetal suppurative bronchopneumonia
What gross finding is pathognomonic for EHV-1 abortion in mares?
A fibrinous tracheal cast in the fetus
What are three causes of thyroid abnormalities in foals?
- Iodine deficient diet
- Goitrogenic substances in the diet
- Inherited genetic condition
Which organ is the target organ in protozoal infections?
The brain! Always take this for histology.
What are the six major steps in the diagnostic process for fetal loss?
- Examine the placenta for any abnormalities
- External examination of the fetus
- Estimate gestational age of the fetus
- Determine the state of preservation at the time of expulsion
- Classify the fetal death
- Perform necropsy to identify gross findings
