FOP 2 Equine notes + presentation Flashcards
overall pregnancy rate in mares
50%
in mares, when investigating failure of pregnancy, is it more important to investigate the placenta or the fetus?
arguably, the placenta
why is the birth of live twins so rare in horses?
lack of functional reserve in the equine placenta
when will we see a lack of villi in regions of the equine placenta?
- Twinning, where the connecting surfaces of adjoining
placentas meet. - Ascending infection, which is one of the common ways
that agents gain access to the fetus and membranes in
horses. - Premature separation of the placenta, that occurs, in
part, with cervical laxity or with body pregnancies.
>body pregnancy is where umbilical cord and fetus attach in body of placenta rather than horn: pushes out cervix, so we get avillus area where placenta sticks out of the ervix
length of the normal umbilical cord in the mare. What happens if it is too long, or too short?
-normal is between 36 and 83 cm long
-Longer may strangle the fetus, develop torsion, and necrosis of the cervical pole of the placenta.
- shorter may rupture prematurely in labour or prematurely separate at the site of attachment.
how many twists should the equine umbilical cord have?
The cord should have no more than 4 twists.
how often can we determine the cause of failure of pregnancy in the mare by examining the placenta and umbilical cord?
1/2 of cases
what region of the placenta is it important to examine to determine the cause of FOP in the mare? why?
cervical star
-most infectious cases (aside from EHV) are related to ascending vaginal infection
Infection and inflammation of the placenta releases what?
-proinflammatory cytokines that cause fetal ‘distress’ and abortion
what fetal changes can Equid alphaherpesvirus 1 cause?
An important cause of abortion and there are prominent changes in the fetus. One or more of the following may be found
* fibrin cast in the trachea
* interstitial pneumonia
* focal necrosis in the liver
common way to begin an outbreak of EHV-1 in a group of mares:
Introduction of an infected mare to a group of naïve mares
what type of vaccine do we have for Equid alphaherpesvirus 1?
killed vaccine that requires multiple injections
normal fetus to placenta weight ratio is what? why should we weight these?
normal ratio is 10:1
-can examine to identify placental edema – an indication of fescue toxicosis
What part of the chorioallantois would you routinely sample when investigating an abortion?
cervical star - this is where infectious disease occurs most often in equine placentas
Mummification of a fetus in mares is associated with what situations?
twins
How would you determine if there were torsion of the umbilical cord and what would you expect to find in the fetus to confirm this?
- More than 3 twists in umbilical cord; look for evidence of fetal stress (meconium staining) or autolysis (indicating death prior to abortion)
-see effects of venous, arterial, urachal obstruction
-swelling of urachus
What is the difference between an allantoic pouch and a chorioallantoic pouch?
chorioallantoic pouches - structures opposite the endometrial cups
allantoic pouches - 1 or 2 is normal, more is abnormal, accumulation of material in allantoic membrane. Basically, outpouchings of the allantois that may have a long stalk.
Why does Streptococcus equi zooepidemicus cause abortion in mares when it only affects a small part of the placenta?
-occurs at cervical star: exudate and necrosis
Infection and inflammation of the placenta (placentitis) causes the release of inflammatory cytokines which result in fetal distress which can lead to abortion + equine placenta has a lack of functional reserve, so even a small loss of surface area can lead to FOP
What is a hippomane?
found in the allantoic cavity in every mare placenta - allantoic precipitate, of the allantoic fluid: carbohydrate, protein…
When is placental mineralization abnormal?
placental infarct can lead to abnormal mineralization due to necrosis
- Abnormal is there’s necrosis, inflammation, or not in ruminant/pig
normal:
- When in the chorioallantois in early pregnancy in ruminants, in yolk sac remnants, where adjoining placentae touch (pigs)
what is unique about the cervix of the mare compared with other species?
it is “loose”, ie. a worse barrier to the outside world than in other species
where do we find the fetus in the mare placenta? how is it positioned?
-arrangement is very consistent
-fetus always develops at the bifurcation of the uterus
-umbilical cord is always dorsal, with the foal lying on its back
-when the fetus gets big enough, the legs stretch into the non-pregnant horn, with head near the cervix
how does the length of the umbilical cord compare with the lengths of the uterine horns?
-about the same length as the pregnant horn and a little but longer than the non-pregnant horn
where does the mare placenta rupture during birth?
cervical star
