Lecture 27 - Non-infectious causes of Pregnancy Loss Flashcards
Define early embryonic mortality
Loss of conceptus prior to maternal reconition of pregnancy (MRP)
T/F: Early embryonic mortality is the same thing as early embryonic death.
False
Early embryonic mortality is inapparent, except in ______, so assumption is subferitlity/infertility.
Mares
Early embryonic mortality leads to a _____ return to estrus.
Regular
Define late embyronic mortality
Embryonic loss between MRP and competion of organogenesis and leads to pseudopregnancy or irregular reutrn to estrus, depending upon cause of pregnancy loss.
Define resorption
Embryonic (or fetal) tissues break down and components are dispered.
No discernible conceptus is expelled (some tissues may be discharged, but it iwll uslaly be inapparent to owner)
Define mummification
Death of one or more fetuses in the absence of ascending bacterial infection.
Usually in the presence of a CL and the absence of cervical dilation.
Fetuses and placentas become dessicated via absorption of fetal fluids.
Mummification is most commonly seen in:
Swine, pygmy goats, and cattle
In cattle, does administration of PGF resolve all cases of mummifcation?
No - surgical removal may be required
Define maceration
Occurs with death of fetus in the presence of bacterial infection.
Luteolysis eventually occurs resulting in cervical dilation and additional colonization of fetal tissues by ascending organisms.
Macerated fetus may, ararely, be retained within the uterus.
Maceration is most commonly seen in _____.
cattle
Define abortion
Expulsion or delivery of a fetus, live or dead, that is incapable of life outside of the uterus due to prematureity, i.e., it is NONVIABLE
An embryo “becomes” a fetus once differentiation/oragnogenesis is complete
Define late-term abortion
Abortion occuring in late gestation to near term.
Term is when the fetus is due; therefore, there cannot be suche a thing as “late term”
Define stillbirth
Offspring born dead or found deceased shortly after birth at term.
Most result form severe hypoxia during parturition.
Embryonic period relatively tenuous in the mare, particularly during hte first 25 days. Why?
Because she solely relies on her CL to maintain pregnancy
Intrinisc causes of embryonic mortality in the mare
Foal heat breeding
Endometrial degeneration
“progesterone deficiency” - RARE
Why does foal heat breeding lead to intrinisc cause of embryonic mortality in the mare?
Incomplete involution, residual inflammation when embryo arrives in uterus 5 days after fertilization.
Loss may occur before or after MRP
Endometrial degeneartion leads to embryonic mortality before or after MRP?
AFTER - leading to pseudopregnancy type I
Extrinsic causes of embryonic mortality in the mare:
Physiologica “stress” –> lysis of the primary CL
Nutrition - questionable b/c embryo is small, its nutritional needs are miniscule, and the embryo is equipped with its own nutritional supply (yolk sac)
Embryonic/fetal causes of embryonic and early fetal mortality in the mare:
- Chromosomal abnormalities
- Poor oocyte quality in mares of advanced age
- Spontaneous, sporadic chromosomal abnormality
- Immunogenetic influences
- Mare-stallion incompatability - RARE
- Mare-jack breeding - failure to produce endometrial cups
Mare-jack breeding leads to failure to produce _____
Endometrial cups
What is “body prengnancy” in the mare?
- Embryo fixes and implants at the body of the uterus (unusual - normally implants at base of horn so back legs grow into one horn, and front part goes into uterus)
- Placenta expands into both horns, but relatively insufficient space
- Abortion occurs at 8-9 months
- Foal often alive at delviery but not viable (bones haven’t ossified yet
Most commonly diagnosed cause of equine abortion is ________.
Twinning
Possible outcomes of twinning in mares:
- Birth of one live and one mummy at term
- Deliveyr of two live foals in late-term abortion - poor viability
- Incredibly rare, birth of two live, viable foals at term
- Increased risk for dystocia the later in gestation the abortion occurs and with foals delivered at term
The most common outcome of twinning in the mare is:
Delivery of two live foals in mid-late gestation, neither of which are viable
A possible complication of twinning in mares is reatined fetal membranes, which can lead to what?
Metritis –> endotoxemia –> laminitis –> death
In twinning, there is a delayed uterine involution in the mare, therefore, do NOT breed back on ______.
Foal heat
Deficiencies of which minerals will decrease embryonic survival in the cow?
Cu, Se, and Mn
Effect of ingestion of endophyte-infected tall fescue in pregnant cattle
Significantly lower pregnancy rates if grazing on heavily contaminated pastures due to embryonic loss prior to or after MRP.
Ergovaline may affect pregnancy maintenance via ergot-induced hyperthermia –> leading to luteolysis
Tall fescue toxicity in pregnant cows is most relevant in mid to late ______.
Summer
Sources of high nitrate
Nitrate-accumulating plants (sudan grass, johnson grass, pigweed)
Drought-damaged corn (green stalks and stubble)
Heavily fertilized pastures
Pathophysiology of nitrate intoxication in cattle
- Nitrate converted to nitrite in rumen –>
- Nitrite enters circulation, oxidizes ferrous (Hb) to ferric ion (MHb)
- MHb does not bind oxygen –> hypoxemia
- Fetal hypoxia –> stress +/- death –> trigger abortion
Nitrate intoxication causes ___ gestation abortion in cattle.
Late
Abortion due to nitrate intoxication occurs at ____ levels of intoxication, than in acute death of the dam.
lower
How do these toxins cause abortion in cattle:
Cyanogenic sugars from johnson and sudan grass
Pesticides applied to alternative forages
Aflatoxins in drought-damaged corn
These toxins cause systemic maternal compromise, leading to abortion
Pine needle abortion in cattle causes abortion due to ______ , which causes vasoconstriction of the caruncle bed, decreasing oxyen/blood flow to the placentome, and hte fetus becomes stressed.
Isocupressic acid
At what time during gestation does pine needle abortion cause abortion in cattle?
Late-to term
After ingestion of pine needles in cattle, abortion occurs on average ____ after ingestion starts. ABbortions should stop around ___ after removing cows from affected pasture.
2 days; 2 days
Locoweed intoxication in cattle requires _____ of ingestion for it to become toxic.
4-6 weeks
Reproductive consequences of locoweed intoxication in cattle
- Abortion at any stage of gestation, fetal malformations
- Increases fetal vascular resistance –> cardiac insufficiency –> fluid accumulation –> fetal death –> abortion
toxic principle of locoweed in cattle
Indolizidine alkaloid swainsonine
Abortion in cattle can be iatrogenic, from inadvertent administration of PGF between ___ week and ___ months of pregnancy.
1 week; 3-5 months of pregnancy
AI of cows believed to be in heat, but that are actually pregnant can cause ____
Abortion
Small ruminats have a high rate of embronic loss. Why?
In the doe, Pregnancy maintenance is soley CL dependent! So any stress or trauma in the doe can induce luteolysis and terminate the pregnancy.
Causes for embryonic loss in small ruminants
- Extreme maternal malnutrition
- Genetic abnormalities of the embryo
- Medication administration
- Inadvertent PGF
- High doses of albendazole
- Toxins
- Phytoestrgoens in plants
- Veratrum californicum - teratogenic effects
We want the background rate of abortions in small ruminants to be less than ___%
5
Causes for abotion in small ruminants
- Stress or trauma, especially in does
- Rough handling, shearing of ewes
- Predatory attacks
- Genetic (ex - habitual abortion in Angora goats)
- Medication administration during pregnancy
- Inadvertant PF to does at any stage, ewes before 50 days gestation
- certain anthelmintics during certain gestational windows (levamisole in late gestation, albendazole in embryonic period)
- Toxins (nitrate poisoning, locoweed)
- Pregnancy toxemia (does abort in latter/terminal stage, if disease is severe, ewes may die before aborting)
Causes of pregnancy loss in the sow
- Stress or trauma
- Carbon monoxide poisoning
- Inadvertent administration of PGF at ANY stage of gestation
Causes for pregnancy loss in the hembra:
- Stress or trauma
- Transportation
- Extreme ambient temperature
- Medication administration
- Exogneous corticosteroids, even small amounts in ophthalmic ointment in second half of gestation
- Single dose of PGF at ANY stage of gestation
In the bitch, expect to lose _____% of all conceptuses by 8 weeks of gestation.
11-13%
What is hypoluteodism (luteal insufficiency) in the bitch?
- Rare problem
- P4 begins to decline abnormally between days 25-35 of gestation and is lower than average by day 35-40
How to treat hypoluteodism in the canine? Consequences?
- Tx with atrenogest supplementation
- Consequences: masculinization of female fetuses - clitoral hypertorphy; and cryptorchidism in male puppies
Exogenous corticosteroid administration in the pregnant bitch causes ____
Abortion
Administration of chloramphenicol in the pregnant bitch leads to _____
Fetal death
Deficits in these two nutrients in the queen causes embryonic mortality, abortion, and congenital malformations
Vitamin A
Taurine
