2. Canine Pregnancy Flashcards
when does parturition occur relative to:
LH surge
ovulation
cytological diestrus
first breeding
*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)
what is the best date to use to time parturition?
ovulation date
-breeding dates are much harder to use
fertile period is when compared to ovlation?
2-4 days post ovulation
Canine gestation =
= 63 days +/- 1 day from ovulation
* 63days=9weeks
is progesterone in the bitch only elevated is she is pregnant? what is this hormone produced by?
Important!!!àprogesterone is elevated regardless of pregnant or not
◦ Produced by the CLs
when does progesterone start to decrease relative to parturition?
◦ Decreases to baseline 24-48 hours prior to parturition
what level of progesterone is required for pregnancy maintenance?
> 2ng/ml for maintenance
what are the hormones of pregnancy?
-progesterone
-prolactin
-LH
-Relaxin
-Estrogen
purpose of prolactin during pregnancy and otherwise?
◦ Required for maintenance of CLs > indirectly maintain progesterone
> 35 days until term
◦ Important for milk production
◦ Pituitary origin
purpose of prolactin during pregnancy and otherwise?
◦ Required for maintenance of CLs > indirectly maintain progesterone
> starts to be produced 35 days until term
◦ Important for milk production
◦ Pituitary origin
purpose of LH during pregnancy
◦ Important for CL maintenance
purpose of relaxin during pregnancy? how is it produced? when is it present and how can we take advantage of this?
◦ Only hormone that is different in pregnancy vs non pregnancy
◦ Produced by the placenta
◦ Can be used to diagnose pregnancy
how does estrogen change during the course of pregenancy?
◦ Drops following peak in estrus
◦ Remains low until just prior to whelping
physiologic systems affected during pregnancy
Many systems affected
* Renal
* Cardiovascular
* Digestive
* Hepatobiliary
* Hematologic
how severe can pregnancy associated anemia be? what is it caused by?
◦ 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
what responses do we see in WBCs and acute phase proteins that are believed to be a response to the feto-placental unit?
*Increase in acute phase proteins
*Leukocytosis w/o L shift – starts @ implantation
Phases of pregnancy and their timing relative to LH surge
Can be divided into 3 sections:
- Fertilization + early embryo (fertilization => d20-22 post LH)
- Late embryo to fetal ossification/calcification (d20-22 => 40-42d post LH)
- Fetus to parturition (d40-42 post LH => parturition)
what occurs during the fertilization and early embryo stage of pregnancy?
-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
what occurs during the late embryo to fetal ossification/calcification stage of pregnancy?
Start of fetal development; organogenesis
what occurs during the fetus to parturition stage of pregnancy?
Ossification/mineralization
Rapid growth period
during what stage of pregnancy should we be especially careful about exposing the bitch to toxins
Embryotoxicity critical time point:
6-20 days post-LH
when does the canine placenta develop
Placenta develops @ approx. 20-22 days
what kind of placenta do dogs have? what are its characteristics for its different parts?
Endotheliochorial zonary placentation (circumferential)
Marginal hematomas
◦ Present at zonary band
◦ Maternal blood hemoglobin is metabolized to uteroverdin
◦ Embryo gets iron from here
methods of pregnancy diagnosis?
Abdominal palpation
Abdominal ultrasound
Abdominal radiographs
Relaxin
what time is best to diagnose pregnancy via abdominal palpation and why?
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
when during pregnancy can we use abdominal ultrasound for diagnosis? pros and cons?
◦ 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
when are radiographs useful for pregnancy diagnosis? pros and cons?
◦ 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
when can we use relaxin to diagnose pregnancy? pros and cons?
◦ > 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
why is gestational aging important?
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
most accurate way to determine due dates? what can provide us with even more accuracy?
Ovulation timing is the most accurate way to determine due dates. Gestational ageing using ultrasound in conjunction with ovulation timing provides even more accuracy.
gold standard for gestational aging? when should we do this? how?
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
how much weight should the bitch gain in the last 3rd of pregnancy?
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
optimal diet for pregnancy
◦ 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)
should we supplement with calcium during pregnancy? why or why not? what should the Ca:P ratio be?
◦ 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
considerations about raw diets during pregnancy
◦ 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
considerations regarding diets high in legumes during pregnancy
Believed that legumes bind calcium
>less useable calcium available
◦ Predisposition to hypocalcemia during labor or post partum
considerations regarding diets high in legumes during pregnancy
Believed that legumes bind calcium
>less useable calcium available
◦ Predisposition to hypocalcemia during labor or post partum
exercise considerations during pregnancy
◦ Should be moderate
◦ Typically bitch can set her own pace
housing considerations during pregnancy. Should she be housed with other dogs? when should she go to the whelping area? temp and humidity?
◦ 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
vaccination considerations during pregnancy? vaccine timing around pregnancy?
◦ Should not give vaccines during pregnancy
> especially not modified live
◦ Ideally would be vaccinated earlier than 2 weeks prior to breeding
deworming considerations for pregnant bitch
Should be dewormed regularly & appropriately for pregnancy
drug considerations for pregnancy
◦ 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
drug categories for use in pregnancy and what they mean
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
metabolic diseases to watch for during pregnancy
◦ Gestational diabetes mellitus
◦ Pregnancy toxemia
Non infectious causes of pregnancy loss
◦ Maternal disease, poor nutrition, drugs, genetic disease, aged oocytes, maternal stress, hypoluteoidism
if a pregnancy is lost, when is it considered early embryonic death? what happens?
◦ Early embryonic death > resorptions > 1st half of pregnancy
if a pregnancy is lost, when is it considered an abortion? what possible occurrences are there?
◦ 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
Review of glucose homeostasis
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
is gestational diabetes mellitus common
no, rare overall
pathogenesis of gestational diabetes mellitus
Progesterone
>insulin resistance
>decreased intracellular glucose uptake
>decreased intracellular glucose reserve + increase blood glucose
Progesterone increases growth hormone which is an insulin antagonist
clinical signs of gestational diabetes mellitus? Diagnosis methods?
Clinical signs = similar to diabetes mellitus in all dogs (PU/PD), polyphagia, weight loss
Diagnosis = hyperglycemia + glucosuria
how do we treat gestational diabetes mellitus? what happens if we do not treat? Is this condition generally reversible?
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
what is pregnancy toxemia associated with in terms of nutrients?
Associated with lack of carbohydrates or alteration in carbohydrate metabolism
when during gestation do we generally see pregnancy toxemia?
Occurs in late gestation
risk factors for pregnancy toxemia
◦ Prolonged anorexia
◦ Inappropriate nutrition
◦ Intake of carbohydrates < what is needed
◦ Increased litter size
◦ Some form of stressor (eg. change in environment, concurrent illness)
pathogenesis of pregnancy toxemia
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
clinical signs of pregnancy toxemia
◦ Anorexia
◦ Depression
◦ Weakness
◦ Ataxia
◦ Collapse, seizures, coma
how do we diagnose pregnancy toxemia?
◦ Hypoglycemia + ketonuria without glucosuria
how do we treat pregnancy toxemia?
◦ 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
normal fetal heart rate should be:
180-200bpm
purpose of fetal monitoring
Can be done to both monitor a high risk pregnancy or to help determine to fetal readiness for birth
methods of fetal monitoring
-Tocodynamometry (Whelp Wise TM)
-Radiographs
-Ultrasound
what does Tocodynamometry (Whelp Wise TM) detect?
◦ Detects changes in intrauterine & intra-amniotic pressures
◦ Monitors fetal viability & well-being
how can we use ultrasound for fetal monitoring? what should we look for?
◦ 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
how can we use radiographs for fetal monitoring? what should we look for?
◦ 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
What happens if the bitch isn’t bred, or doesn’t conceive?
Pseudopregnancy
describe the state of pseudopregnancy, hormonally and behaviourally
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?
is measuring progesterone useful for determining pregnancy status?
Measuring progesterone is NOT useful to determine pregnancy status
difference in diagnostic variables for gestational diabetes vs pregnancy toxemia
Gestational Diabetes = HYPERglycemia & glucose in the urine +/- ketones
Pregnancy Toxemia = HYPOglycemia & NO glucose in the urine + ketones
