Lecture 27 - Non-infectious causes of Pregnancy Loss

Question 1

Define early embryonic mortality

Answer 1

Loss of conceptus prior to maternal reconition of pregnancy (MRP)

Question 2

T/F: Early embryonic mortality is the same thing as early embryonic death.

Answer 2

False

Question 3

Early embryonic mortality is inapparent, except in ______, so assumption is subferitlity/infertility.

Answer 3

Mares

Question 4

Early embryonic mortality leads to a _____ return to estrus.

Answer 4

Regular

Question 5

Define late embyronic mortality

Answer 5

Embryonic loss between MRP and competion of organogenesis and leads to pseudopregnancy or irregular reutrn to estrus, depending upon cause of pregnancy loss.

Question 6

Define resorption

Answer 6

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)

Question 7

Define mummification

Answer 7

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.

Question 8

Mummification is most commonly seen in:

Answer 8

Swine, pygmy goats, and cattle

Question 9

In cattle, does administration of PGF resolve all cases of mummifcation?

Answer 9

No - surgical removal may be required

Question 10

Define maceration

Answer 10

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.

Question 11

Maceration is most commonly seen in _____.

Answer 11

cattle

Question 12

Define abortion

Answer 12

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

Question 13

Define late-term abortion

Answer 13

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”

Question 14

Define stillbirth

Answer 14

Offspring born dead or found deceased shortly after birth at term.

Most result form severe hypoxia during parturition.

Question 15

Embryonic period relatively tenuous in the mare, particularly during hte first 25 days. Why?

Answer 15

Because she solely relies on her CL to maintain pregnancy

Question 16

Intrinisc causes of embryonic mortality in the mare

Answer 16

Foal heat breeding

Endometrial degeneration

“progesterone deficiency” - RARE

Question 17

Why does foal heat breeding lead to intrinisc cause of embryonic mortality in the mare?

Answer 17

Incomplete involution, residual inflammation when embryo arrives in uterus 5 days after fertilization.

Loss may occur before or after MRP

Question 18

Endometrial degeneartion leads to embryonic mortality before or after MRP?

Answer 18

AFTER - leading to pseudopregnancy type I

Question 19

Extrinsic causes of embryonic mortality in the mare:

Answer 19

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)

Question 20

Embryonic/fetal causes of embryonic and early fetal mortality in the mare:

Answer 20

• 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

Question 21

Mare-jack breeding leads to failure to produce _____

Answer 21

Endometrial cups

Question 22

What is “body prengnancy” in the mare?

Answer 22

• 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

Question 23

Most commonly diagnosed cause of equine abortion is ________.

Answer 23

Twinning

Question 24

Possible outcomes of twinning in mares:

Answer 24

• 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

Question 25

The most common outcome of twinning in the mare is:

Answer 25

Delivery of two live foals in mid-late gestation, neither of which are viable

Question 26

A possible complication of twinning in mares is reatined fetal membranes, which can lead to what?

Answer 26

Metritis --\> endotoxemia --\> laminitis --\> death

Question 27

In twinning, there is a delayed uterine involution in the mare, therefore, do NOT breed back on \_\_\_\_\_\_.

Answer 27

Foal heat

Question 28

Deficiencies of which minerals will decrease embryonic survival in the cow?

Answer 28

Cu, Se, and Mn

Question 29

Effect of ingestion of endophyte-infected tall fescue in pregnant cattle

Answer 29

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

Question 30

Tall fescue toxicity in pregnant cows is most relevant in mid to late \_\_\_\_\_\_.

Answer 30

Summer

Question 31

Sources of high nitrate

Answer 31

Nitrate-accumulating plants (sudan grass, johnson grass, pigweed) Drought-damaged corn (green stalks and stubble) Heavily fertilized pastures

Question 32

Pathophysiology of nitrate intoxication in cattle

Answer 32

1. Nitrate converted to nitrite in rumen --\> 2. Nitrite enters circulation, oxidizes ferrous (Hb) to ferric ion (MHb) 3. MHb does not bind oxygen --\> hypoxemia 4. Fetal hypoxia --\> stress +/- death --\> trigger abortion

Question 33

Nitrate intoxication causes ___ gestation abortion in cattle.

Answer 33

Late

Question 34

Abortion due to nitrate intoxication occurs at ____ levels of intoxication, than in acute death of the dam.

Answer 34

lower

Question 35

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

Answer 35

These toxins cause systemic maternal compromise, leading to abortion

Question 36

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.

Answer 36

Isocupressic acid

Question 37

At what time during gestation does pine needle abortion cause abortion in cattle?

Answer 37

Late-to term

Question 38

After ingestion of pine needles in cattle, abortion occurs on average ____ after ingestion starts. ABbortions should stop around ___ after removing cows from affected pasture.

Answer 38

2 days; 2 days

Question 39

Locoweed intoxication in cattle requires _____ of ingestion for it to become toxic.

Answer 39

4-6 weeks

Question 40

Reproductive consequences of locoweed intoxication in cattle

Answer 40

* Abortion at any stage of gestation, fetal malformations * Increases fetal vascular resistance --\> cardiac insufficiency --\> fluid accumulation --\> fetal death --\> abortion

Question 41

toxic principle of locoweed in cattle

Answer 41

Indolizidine alkaloid swainsonine

Question 42

Abortion in cattle can be iatrogenic, from inadvertent administration of PGF between ___ week and ___ months of pregnancy.

Answer 42

1 week; 3-5 months of pregnancy

Question 43

AI of cows believed to be in heat, but that are actually pregnant can cause \_\_\_\_

Answer 43

Abortion

Question 44

Small ruminats have a high rate of embronic loss. Why?

Answer 44

In the doe, Pregnancy maintenance is soley CL dependent! So any stress or trauma in the doe can induce luteolysis and terminate the pregnancy.

Question 45

Causes for embryonic loss in small ruminants

Answer 45

* Extreme maternal malnutrition * Genetic abnormalities of the embryo * Medication administration * Inadvertent PGF * High doses of albendazole * Toxins * Phytoestrgoens in plants * Veratrum californicum - teratogenic effects

Question 46

We want the background rate of abortions in small ruminants to be less than \_\_\_%

Answer 46

5

Question 47

Causes for abotion in small ruminants

Answer 47

* 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)

Question 48

Causes of pregnancy loss in the sow

Answer 48

* Stress or trauma * Carbon monoxide poisoning * Inadvertent administration of PGF at ANY stage of gestation

Question 49

Causes for pregnancy loss in the hembra:

Answer 49

* 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

Question 50

In the bitch, expect to lose \_\_\_\_\_% of all conceptuses by 8 weeks of gestation.

Answer 50

11-13%

Question 51

What is hypoluteodism (luteal insufficiency) in the bitch?

Answer 51

* Rare problem * P4 begins to decline abnormally between days 25-35 of gestation and is lower than average by day 35-40

Question 52

How to treat hypoluteodism in the canine? Consequences?

Answer 52

* Tx with atrenogest supplementation * Consequences: masculinization of female fetuses - clitoral hypertorphy; and cryptorchidism in male puppies

Question 53

Exogenous corticosteroid administration in the pregnant bitch causes \_\_\_\_

Answer 53

Abortion

Question 54

Administration of chloramphenicol in the pregnant bitch leads to \_\_\_\_\_

Answer 54

Fetal death

Question 55

Deficits in these two nutrients in the queen causes embryonic mortality, abortion, and congenital malformations

Answer 55

Vitamin A Taurine