2. Canine Pregnancy

Question 1

when does parturition occur relative to:
LH surge
ovulation
cytological diestrus
first breeding

Answer 1

*65 days (+/- 1 day) after LH surge
*63 days (+/-1 day) after ovulation
*57 days after cytological diestrus
*57-72 days from 1st breeding date (lots of variability)

Question 2

what is the best date to use to time parturition?

Answer 2

ovulation date
-breeding dates are much harder to use

Question 3

fertile period is when compared to ovlation?

Answer 3

2-4 days post ovulation

Question 4

Canine gestation =

Answer 4

= 63 days +/- 1 day from ovulation
* 63days=9weeks

Question 5

is progesterone in the bitch only elevated is she is pregnant? what is this hormone produced by?

Answer 5

Important!!!àprogesterone is elevated regardless of pregnant or not
◦ Produced by the CLs

Question 6

when does progesterone start to decrease relative to parturition?

Answer 6

◦ Decreases to baseline 24-48 hours prior to parturition

Question 7

what level of progesterone is required for pregnancy maintenance?

Answer 7

> 2ng/ml for maintenance

Question 8

what are the hormones of pregnancy?

Answer 8

-progesterone
-prolactin
-LH
-Relaxin
-Estrogen

Question 9

purpose of prolactin during pregnancy and otherwise?

Answer 9

◦ Required for maintenance of CLs > indirectly maintain progesterone
> 35 days until term
◦ Important for milk production
◦ Pituitary origin

Question 9

purpose of prolactin during pregnancy and otherwise?

Answer 9

◦ Required for maintenance of CLs > indirectly maintain progesterone
> starts to be produced 35 days until term
◦ Important for milk production
◦ Pituitary origin

Question 10

purpose of LH during pregnancy

Answer 10

◦ Important for CL maintenance

Question 11

purpose of relaxin during pregnancy? how is it produced? when is it present and how can we take advantage of this?

Answer 11

◦ Only hormone that is different in pregnancy vs non pregnancy
◦ Produced by the placenta
◦ Can be used to diagnose pregnancy

Question 12

how does estrogen change during the course of pregenancy?

Answer 12

◦ Drops following peak in estrus
◦ Remains low until just prior to whelping

Question 13

physiologic systems affected during pregnancy

Answer 13

Many systems affected
* Renal
* Cardiovascular
* Digestive
* Hepatobiliary
* Hematologic

Question 14

how severe can pregnancy associated anemia be? what is it caused by?

Answer 14

◦ Reduction of PCV (packed cell volume) by up to 30%
◦ Actually caused by hemodilution > increase in blood volume; not a decrease in RBCs

> normal change that occurs virtually all pregnant bitches

Question 15

what responses do we see in WBCs and acute phase proteins that are believed to be a response to the feto-placental unit?

Answer 15

*Increase in acute phase proteins
*Leukocytosis w/o L shift – starts @ implantation

Question 16

Phases of pregnancy and their timing relative to LH surge

Answer 16

Can be divided into 3 sections:

1. Fertilization + early embryo (fertilization => d20-22 post LH)
2. Late embryo to fetal ossification/calcification (d20-22 => 40-42d post LH)
3. Fetus to parturition (d40-42 post LH => parturition)

Question 17

what occurs during the fertilization and early embryo stage of pregnancy?

Answer 17

-Fertilization
-Embryos (blastocyst stage) descend from oviducts into uterus 10-12 days after the LH surge
-Trans-uterine migration occurs
-At 18-20 days post LH surge, implantation begins
-Implantation ends 2 days later

Question 18

what occurs during the late embryo to fetal ossification/calcification stage of pregnancy?

Answer 18

Start of fetal development; organogenesis

Question 19

what occurs during the fetus to parturition stage of pregnancy?

Answer 19

Ossification/mineralization
Rapid growth period

Question 20

during what stage of pregnancy should we be especially careful about exposing the bitch to toxins

Answer 20

Embryotoxicity critical time point:
6-20 days post-LH

Question 21

when does the canine placenta develop

Answer 21

Placenta develops @ approx. 20-22 days

Question 22

what kind of placenta do dogs have? what are its characteristics for its different parts?

Answer 22

Endotheliochorial zonary placentation (circumferential)

Marginal hematomas
◦ Present at zonary band
◦ Maternal blood hemoglobin is metabolized to uteroverdin
◦ Embryo gets iron from here

Question 23

methods of pregnancy diagnosis?

Answer 23

Abdominal palpation
Abdominal ultrasound
Abdominal radiographs
Relaxin

Question 24

what time is best to diagnose pregnancy via abdominal palpation and why?

Answer 24

day 25-35 before this, too small after this, the uterus will just feel like an enlarged structure as apposed to palpating distinct circular masses

Question 25

when during pregnancy can we use abdominal ultrasound for diagnosis? pros and cons?

Answer 25

◦ Day 19 ◦ Most often done >24 days of pregnancy ◦ Important for gestational ageing; only gives estimate of fetal number ◦ Not as accurate for ageing or fetal number when done @ >37 days (fetuses too big for screen) ◦ Fetal maturation ◦ Assessment of fetal viability

Question 26

when are radiographs useful for pregnancy diagnosis? pros and cons?

Answer 26

◦ 45 days of pregnancy = mineralization ◦ <45 days of pregnancy > soft tissue density in caudo-ventral abdomen ◦ Can’t distinguish from other causes of uterine enlargement (eg. pyometra) ◦ Fetal count & size ◦ Not accurate for gestational ageing ◦ Best results > 3-5 days prior to due date

Question 27

when can we use relaxin to diagnose pregnancy? pros and cons?

Answer 27

◦ > 19-21 days of pregnancy; levels peak mid-pregnancy ◦ Often measured at 24-26 days of pregnancy ◦ If too early > false negative > recheck or small litter in giant breed dog ◦ If resorptions/abortions > false positive

Question 28

why is gestational aging important?

Answer 28

To know when they are due! ◦ Bitches that require elective c-sections (brachycephalics, singleton litters) ◦ Bitches that may require additional monitoring during whelping ◦ High risk pregnancy bitches ◦ Bitches that require progesterone supplementation to maintain pregnancy -Premature puppies have a high mortality risk -Canine placenta cannot support fetuses >2 days past whelping date > intra-uterine fetal death

Question 29

most accurate way to determine due dates? what can provide us with even more accuracy?

Answer 29

Ovulation timing is the most accurate way to determine due dates. Gestational ageing using ultrasound in conjunction with ovulation timing provides even more accuracy.

Question 30

gold standard for gestational aging? when should we do this? how?

Answer 30

Ultrasound = gold standard -More accurate results when done @ <37 days of gestation Fetal and extra-fetal measurements ◦ Examples: crown-rump length, biparietal diameter, body diameter, inner chorionic cavity Fetal maturation & organ development ◦ Amniotic vesicle as early as 19-21 days ◦ Heart beat 1st visible at 23-26 days ◦ Placenta becomes zonary at 29-31 days ◦ At 32 days, placental edges starts to curl inwards ◦ At 37 days, fetus is longer than zonary placenta If presented with pregnancy >37 days ◦ Biparietal diameter used for due date estimate looking at extra-fetal measurements and organ development at the same time is more accurate than one method alone

Question 31

how much weight should the bitch gain in the last 3rd of pregnancy?

Answer 31

Last 3rd of canine pregnancy = period of rapid fetal growth – bitch should gain 25-30% of her body weight by time of whelping ◦ Should take number of fetuses, breed & age of bitch, activity level & bitch’s BCS into consideration

Question 32

optimal diet for pregnancy

Answer 32

◦ Should be on diet with increased protein, carbohydrates and minerals + increased calories ( >375kcal/cup) ◦ Small, frequent meals > Especially if not eating well ◦ Diets made especially for growth or lactation (e.g. puppy food, high performance diet)

Question 33

should we supplement with calcium during pregnancy? why or why not? what should the Ca:P ratio be?

Answer 33

◦ Do NOT supplement with calcium during gestation > predisposes to hypocalcemia, dystocia ◦ Ca:P ratio no higher than 1.2:1; no lower than 1:1

Question 34

considerations about raw diets during pregnancy

Answer 34

◦ Not recommended during pregnancy, especially if homemade ◦ Possibility of bacterial transmission from the GI tract to the uterus via the bloodstream > early embryonic death (EED), abortion, placentitis ◦ Should recommend consultation with veterinary nutritionist, especially if homemade

Question 35

considerations regarding diets high in legumes during pregnancy

Answer 35

Believed that legumes bind calcium >less useable calcium available ◦ Predisposition to hypocalcemia during labor or post partum

Question 36

considerations regarding diets high in legumes during pregnancy

Answer 36

Believed that legumes bind calcium >less useable calcium available ◦ Predisposition to hypocalcemia during labor or post partum

Question 37

exercise considerations during pregnancy

Answer 37

◦ Should be moderate ◦ Typically bitch can set her own pace

Question 38

housing considerations during pregnancy. Should she be housed with other dogs? when should she go to the whelping area? temp and humidity?

Answer 38

◦ Should be kept away from any dogs/puppies with unknown vaccine status ◦ Should be introduced to whelping area 5-7 days prior to due date ◦ Temperature + humidity control

Question 39

vaccination considerations during pregnancy? vaccine timing around pregnancy?

Answer 39

◦ Should not give vaccines during pregnancy > especially not modified live ◦ Ideally would be vaccinated earlier than 2 weeks prior to breeding

Question 40

deworming considerations for pregnant bitch

Answer 40

Should be dewormed regularly & appropriately for pregnancy

Question 41

drug considerations for pregnancy

Answer 41

◦ Should be avoided as much as possible during pregnancy ◦ If they are necessary, all drugs should be evaluated while taking physiologic changes that occur in the pregnant bitches into account ◦ Generally short periods of time, moderate doses are better ◦ Drugs have been categorized to help determine which are “safer” to use in pregnancy

Question 42

drug categories for use in pregnancy and what they mean

Answer 42

A) probably safe, may not be studied in dogs/cats B) should be safe if used cautiously. lab animal studies may suggest some adverse effects C) should only be be used if therapeutic benefits outweigh risks. Potential adverse effects D) contraindicated for use during pregnancy; known teratogenic/embryotoxic effects

Question 43

metabolic diseases to watch for during pregnancy

Answer 43

◦ Gestational diabetes mellitus ◦ Pregnancy toxemia

Question 44

Non infectious causes of pregnancy loss

Answer 44

◦ Maternal disease, poor nutrition, drugs, genetic disease, aged oocytes, maternal stress, hypoluteoidism

Question 45

if a pregnancy is lost, when is it considered early embryonic death? what happens?

Answer 45

◦ Early embryonic death > resorptions > 1st half of pregnancy

Question 46

if a pregnancy is lost, when is it considered an abortion? what possible occurrences are there?

Answer 46

◦ Abortions > birth of alive or dead fetus + placenta > 2nd half of pregnancy ◦ Stillbirths ◦ Mummification ◦ Maceration ◦ Fetuses born at this stage cannot survive long outside the uterus

Question 47

Review of glucose homeostasis

Answer 47

High blood sugar >increased insulin secretion >intracellular glucose uptake >stored as glucagon or fat Low blood sugar >decreased insulin secretion + stimulates secretion of glucagon (+ others) >lipolysis, glycogenolysis, gluconeogenesis >increased blood sugar, ketones

Question 48

is gestational diabetes mellitus common

Answer 48

no, rare overall

Question 49

pathogenesis of gestational diabetes mellitus

Answer 49

Progesterone >insulin resistance >decreased intracellular glucose uptake >decreased intracellular glucose reserve + increase blood glucose Progesterone increases growth hormone which is an insulin antagonist

Question 50

clinical signs of gestational diabetes mellitus? Diagnosis methods?

Answer 50

Clinical signs = similar to diabetes mellitus in all dogs (PU/PD), polyphagia, weight loss Diagnosis = hyperglycemia + glucosuria

Question 51

how do we treat gestational diabetes mellitus? what happens if we do not treat? Is this condition generally reversible?

Answer 51

Treatment should be attempted ◦ Insulin – requirement of higher doses is expected ◦ Fluid therapy ◦ Can be challenging Untreated ◦ Larger puppies > dystocia ◦ Increased neonatal morbidity and mortality (in humans at least) -Fetal monitoring is recommended Parturition/termination of pregnancy = usually reverses the condition ◦ Care needs to be taken to decrease the dose of insulin appropriately post-partum – avoid hypoglycemia ◦ Rate of insulin resistance resolution + rate of insulin requirements = unpredicatable

Question 52

what is pregnancy toxemia associated with in terms of nutrients?

Answer 52

Associated with lack of carbohydrates or alteration in carbohydrate metabolism

Question 53

when during gestation do we generally see pregnancy toxemia?

Answer 53

Occurs in late gestation

Question 54

risk factors for pregnancy toxemia

Answer 54

◦ Prolonged anorexia ◦ Inappropriate nutrition ◦ Intake of carbohydrates < what is needed ◦ Increased litter size ◦ Some form of stressor (eg. change in environment, concurrent illness)

Question 55

pathogenesis of pregnancy toxemia

Answer 55

Late pregnancy = decreased ability to produce glucose ◦ Decreased/blunted response to hypoglycemia Hypoglycemia risk is elevated ◦ Decreased ability to produce glucose ◦ Increased requirement for glucose > fetal development & growth Persistent hypoglycemia > insulin secretion suppression > mobilization of fat + release of fatty acids + ketones

Question 56

clinical signs of pregnancy toxemia

Answer 56

◦ Anorexia ◦ Depression ◦ Weakness ◦ Ataxia ◦ Collapse, seizures, coma

Question 57

how do we diagnose pregnancy toxemia?

Answer 57

◦ Hypoglycemia + ketonuria without glucosuria

Question 58

how do we treat pregnancy toxemia?

Answer 58

◦ IV glucose ◦ Correct dehydration, electrolyte abnormalities ◦ High protein, energy rich diet ad libitum ◦ In some instances, no response to tx >pregnancy termination is required ◦ Pregnancy termination will correct the condition ◦ If mild, could respond to diet change only

Question 59

normal fetal heart rate should be:

Answer 59

180-200bpm

Question 60

purpose of fetal monitoring

Answer 60

Can be done to both monitor a high risk pregnancy or to help determine to fetal readiness for birth

Question 61

methods of fetal monitoring

Answer 61

-Tocodynamometry (Whelp Wise TM) -Radiographs -Ultrasound

Question 62

what does Tocodynamometry (Whelp Wise TM) detect?

Answer 62

◦ Detects changes in intrauterine & intra-amniotic pressures ◦ Monitors fetal viability & well-being

Question 63

how can we use ultrasound for fetal monitoring? what should we look for?

Answer 63

◦ Fetal heart rate (FHR) = very good indicator of fetal stress ◦ Prolonged decelerations of FHR = fetal stress ◦ FHRs <180bpm can be associated with fetal stress; <160bpm = severe fetal distress ◦ Transient decrease in FHR during uterine contraction = normal

Question 64

how can we use radiographs for fetal monitoring? what should we look for?

Answer 64

◦ Idea on fetal size (eg. 1 fetus much smaller than others) ◦ Fetal death can be identified > Presence of air in the uterus or around the fetus, skull bones deformed or overlap each other, balling of the fetus or hyperextension of the hindlimbs

Question 65

What happens if the bitch isn’t bred, or doesn’t conceive?

Answer 65

Pseudopregnancy

Question 66

describe the state of pseudopregnancy, hormonally and behaviourally

Answer 66

Hormonal profile almost identical in pregnant vs non- pregnant bitches Behavior can be very similar to pregnant bitches ◦ Weight gain, inappetence, nausea ◦ Mammary development, milk production ◦ “Nurse” toy, guard toys > puppy substitute?

Question 67

is measuring progesterone useful for determining pregnancy status?

Answer 67

Measuring progesterone is NOT useful to determine pregnancy status

Question 68

difference in diagnostic variables for gestational diabetes vs pregnancy toxemia

Answer 68

Gestational Diabetes = HYPERglycemia & glucose in the urine +/- ketones Pregnancy Toxemia = HYPOglycemia & NO glucose in the urine + ketones