Small Animal Reproduction

What are the top 2 reasons for failure to conceive?

poor semen quality

poor timing of insemination

What are weird differences of canine repro physiology?

'pre-lutenization' of granulosa cells by LH causes pre-ovulatory progesterone rise

prime sexual receptivity occurs during period of LOW estrogen and HIGH progesterone

ovulate primary and secondary oocytes that both require period of oviductal maturation

life span of CL is independent of pregnancy status

What are characteristics of the estrous cycle of the bitch?

non-seasonal, monoestrous

When does puberty occur in the bitch?

6 months (up to 24 months)

How long is the estrous cycle of the bitch?

81 days (60-115 days)

How long is proestrus of the bitch?

9 day (5-20 days)

How long is estrus of the bitch?

9 days (5-15 days)

How long is diestrus of the bitch?

60 days (57-63 days)

How long is anestrus in the bictch?

4-6 months

When does ovulation occur in the bitch?

begins 2 days after the onset of estrus

What is the interestrus of intrerestrus interval of the bitch?

diestrus and anestrus stages of estrous cycle

What do vaginal cytology changes occur in response to?

estrogen

What endocrine events occur during proestrus in the bitch?

FSH and LH pulses increase and peaks at estrus

estrogen rises early and peaks prior to estrus

progesterone rises late for pre-luteinization

What are clinical signs of proestrus in the bitch?

vulvar edema and reddening

serosanguineous vulvar discharge

vaginal epithelium begins cornifying

attractiveness (+/- receptivity) to males

**estrogen driven

What endocrine events occur during estrus in the bitch?

LH surge defines the beginning

progesterone continues to rise at predictable rate with serum levels correlating to timing of LH surge and ovulation

estrogen continues to decline to baseline

What are clinical signs of estrus in the bitch?

vulvar edema with decreasing discharge

vaginal cornification remains stable (greater than 90%)

attractive and receptive to males

What are characteristics of ovulation in the bitch?

asynchronous ovulation of primary oocytes over 1-2 days beginning 2 days post-LH surge

require additional 2 days of maturation to secondary oocytes in oviduct

secondary oocytes last 24-48 hours

OVERALL = potentially fertile oocytes are present form Days 4-8 of estrus but fertility is HIGHEST of days 4-6

What are endocrine events during diestrus of the bitch?

progesterone plateaus 20-30 days post-LH surge then declines

prolactin rises 20-30 days post-LH surge, peaks day 40-50

estrogen remains low throughout

What are clinical signs of diestrus of the bitch?

diminished attractiveness to males

resistant to breeding/vaginal procedures

When does luteolysis occur in the bitch?

about 63 days post-ovulation REGARDLESS of pregnancy status

How does luteolysis occur in the bitch? (what's the mechanism?)

decreased prolactin and PGE2 and increased PGF2a

**PGF2a is produced by endometrium in non-pregnant dog

**fetoplacental unit produces PGF2a via uptake and conversion of PGE2 due to rising fetal cortisol at the end of gestation in the pregnant dog

What are characteristics of anestrus in the bitch?

at least 4 months of ovarian quiescence and endometrial repair that is REQUIRED for the HPG axis to reset and uterus to support a new pregnancy

What is the mechanism for ending anestrus?

unknown

What marks the termination of anestrus?

resumption of pulsatile FSH/LH release for folliculogenesis

When should canine breeding management start (when to start ovulation timing)?

5-7 days after onset of proestrus to be the most cost effective

What modalities are utilized to determine ovulation of the bitch?

serial progesterone assays

vaginal cytology

What is a 'split heat'?

proestrus and LH surge occurs but ovulation does not follow

progesterone level declines back below baseline

next proestrus occurs in 2-3 months with apparent normal fertility

What needs to be known to establish a breeding plan for a bitch?

Will any pregnancy do?

Is a large or small litter desired?

Is the sire deceased, foreign?

Interested in dual-sired litter?

Where is sire located? What is the quality of semen, if known?

What are recommendations on how and when to inseminate a bitch based upon?

owners goals and finances

type and quality of semen available from stud

What are different breeding methods?

natural cover

vaginal AI

transcervical insemination (TCI)

surgical AI

What are pros/cons of natural cover?

pro = least expensive (usually) and best semen longevity (usually)

con = no semen analysis available, stud must be local or travel to bitch

What are pros/cons of vaginal AI?

pros = reduces disease transmissions and injury, allows semen analysis

cons = more expensive and comparably successful vs. natural cover

What are pros/cons of transcervical insemination (TCI)?

pros = statistically highest conception rates and litter sizes

cons = more expensive vs vaginal AI, special training and equipment

What are pros/cons of surgical AI?

pros = technically east, can circumvent abnormal anatomy

cons = most expensive, risks of surgery and anesthesia, conception rates, litter size lower or same as TCI

What equipment is needed for vaginal AI?

mavic catheter

AI pipette

What equipment is needed for transcervical AI?

rigid vaginoscope

What is the 'breeding plan' for natural cover?

every other day from day 3-4 until female is unreceptive

What is the 'breeding plan' for fresh semen/cooled shipped semen?

any breeding method depending on quality of semen

breed ONCE on day 5 or TWICE on days 4 and 6

What is the 'breeding plan' for frozen semen?

transcervical or surgical insemination ONLY

Breed ONCE on day 6 or TWICE on days 5 and 6

What is the minimum recommended breeding dose for bitches?

200 million progressively motile semen with ideally 60+% progressively motile and normal morphology

This chart for determine breeding days I starred multiple times. IDK how to create questions from it

What tools can we use to determine the reproductive status (stage and day of estrous cycle) of a bitch?

vaginal cytology

vaginoscopy

luteinizing hormone testing

progesterone (P4) testing

What does vaginal cytology tell us about the reproductive status of a bitch?

stage of cycle

What does progesterone tell us about the reproductive status of a bitch?

day of cycle

What must be understood to interpret vaginal cytology?

understanding of estrogenic effects on reproductive tract

** increased epithelial cell cornification causes exfoliation

** increased vascular permeability causes mucosal edema and diapedesis of RBCs

What are characteristics of vaginal cytology during anestrus?

overall low cellularity with many broken cells

predominant cell type = parabasal cells

mucus strands often present

NO red blood cells or neutrophils (unless vaginitis)

What are characteristics of vaginal cytology during proestrus?

cell numbers begin to increase due to estrogen-mediated proliferation of vaginal epithelium

predominant cell type = intermediate cells and red blood cells with fewer parabasal cells

increased ratio of large to small intermediates and superficial cells to large intermediates throughout stage

neutrophils may be present

What are characteristics of vaginal cytology during estrus?

predominant cell type = superficial cells and large intermediate cells over 80-90%

drop in estrogen reduces diapedesis of RBCs into vaginal lumen = no to minimal RBCs, cellular debris, and mucus

late in stage = large sheets/rafts of superficial cells

What are characteristics of vaginal cytology during diestrus?

predominant cell type = parabasal and small intermediate cells over 40-60%, neutrophils

RBCs, cellular debris, sperm cells vary

What test is utilized for LH testing in the bitch?

WITNESS LH rapid test, a semi-quantitative test

**CANNOT confirm beginning or completion of ovulation

How many WITNESS LH rapid tests are needed to accurately determine the LH surge?

3 daily test as the surge lasts 12-24 hours with 'positive' levels for 36-72 hours and detectable levels for 60-120 hours

What are options for quantitative progesterone tests?

radioimmunoassay (RIA) - historic gold standard

chemiluminescence immunoassay (CLIA) - current gold standard

How is a 2 ng/ml progesterone interpreted?

LH surge

How is a 5 ng/ml progesterone interpreted?

ovulation begins

How is a 10 ng/ml progesterone interpreted?

ovulation considered complete

What is the range of progesterone level for the fertile windo?

10-15 ng/ml = day 4ish

15-20 ng/ml = day 5ish

20-22 ng/ml = day 6ish

What may be occurring if a progesterone rises slowly?

split heat

stalled heat

physiologic stress

What may be occurring if a progesterone rises quickly?

erratic first or second heat

prolific ovulation

What is the 'rule of 2' for canine breeding management?

2 ng/ml progesterone is LH surge x 2is = 5 ng/ml (ovulation) x2 = 10 ng/ml (ovulation complete, start of fertile window) x2 = 20 ng/ml (end of fertile window)

2 days after LH surge = ovulation begins

2 days after ovulation = start of fertile window

2 days after = end of fertile window

What is the most accurate for estimation of canine due dates?

63 days from ovulation

What are other ways to estimate canine due dates?

65 days from LH surge

57 days from cytologic diestrus

57-72 days from single mating

if multiple mating = 57 days from first breeding and 72 days from last breeding

Why is the range so large for canine due date estimation based on only matings?

maximum sperm longevity is 11 days

maximum oocyte longevity is 2 days

female is potentially receptive before, during, or after ovulation

How does the steroid hormone profile differ post-ovulation between pregnancy and diestrus?

virtually identical besides relaxin (only pregnancy) and prolactin

How does maternal recognition of pregnancy occur in canines?

no evidence of any molecular mechanism and is not believed to be 'necessary'

What is the length of gestation in the canine?

61-65 days post-ovulation

varies with size of litter

What type of placentation occurs in the canine?

endotheliochorial, zonary with 3 defined segments

How is pregnancy maintained in the canine?

CL-dependent

What are the 3 zones of the placental sac of the canine placenta?

transfer zone

pigmented zone

avascular zone

What is the transfer zone of the canine placentation?

area with full contact of endometrium for the exchange of nutrients and waste

'true' region of endotheliochorial with 5 layers of tissue

What is the pigmented zone of the canine placentation?

partial erosion of layers especially the maternal endothelium allowing direct blood flow = 5-10% of total IgG transfer

What is the avascular zone of the canine placentation?

no true exchange with maternal side

How is canine pregnancy diagnosed?

ultrasound

hormone testing

radiography

What is the only single way to simultaneously diagnosed, stage, and assess viability of a canine pregnancy?

ultrasound

What do we want to know about a 'maybe' pregnant dog?

Is she pregnant? When is she due?

**from history determine = if intentionally bred or mismating, clarify dates and management, determine options and viability

Remember why due date calculation is such a wide range from a single mating.

maximum sperm longevity is 11 days

maximum oocyte longevity is 2 days

female is potentially receptive before, during, or after ovulation

When multiple matings occur what is the length of the possible window for due dates?

3.5 weeks (over 1/3 the length of gestation)

What can provides the earliest and most specific diagnosis of canine pregnancy? What days can it be preformed?

ultrasonography

**day 17-19 = small uterine swelling/gestation sacs

**day 21-28 = embryo proper, fetal heartbeats, and resorption sites

**NOT sensitive method for litter size estimation

What is the recommended timing for ultrasonographic diagnosis of canine pregnancy?

4 weeks post-ovulation (30 days post-mating)

**allows diagnosis, reasonable fetal count, and viability assessment

What are the most commonly used methods for pregnancy staging via ultrasound?

First Ultrasonographic Detection (FUD)

Fetal Biometry

How is First Ultrasonographic Detection (FUD) utilized for pregnancy staging?

relies on appearance of developmental markers with usefulness for litters of any size

What is the relative 'order' of appearance of developmental markers for First Ultrasonographic Detection (FUD)?

gestational sac

embryo proper and heartbeat

zonary placenta and embryo polarity

anechoic head area

limb buds

skeletal structures and DPTV

urinary bladder

fetal movement

stomach and abdominal-thoracic distinction

kidneys

What is the minimum day of gestation that the gestational sac can be visualized ultrasonographically?

day 17

What is the minimum day of gestation that the embryo proper and heartbeat can be visualized ultrasonographically?

day 21

What is the minimum day of gestation that fetal movement can be visualized ultrasonographically?

day 32

What is used for fetal biometry for pregnancy staging?

measurement of fetal and extra-fetal structures with formulations that determine gestational age OR days to parturition

What types of pregnancy is fetal biometry the most accurate for?

medium-sized breeds

litters mid-gestations

What are different fetal biometry calculations?

crown-rump length (CRL)

biparietal diameter (BPD)

body diameter (transverse at liver and stomach) (BD)

deep portion of diencephalo-telencephalic vesicle (DPTV)

outer uterine diameter (OUD)

inner chorionic cavity (ICC)

What hormone is used for diagnosis of canine pregnancy?

relaxin

What is the ONLY source of detectable levels of relaxin in the dog?

fetoplacental unit (trophoblast cells)

What is used as a semi-quantitative relaxin assay?

WITNESS Relaxin Rapid Test

When is the WITNESS Relaxin Rapid Test the most sensitive and specific

after day 31 of gestation

What is the most sensitive method for estimating litter size?

orthogonal radiographs counting paired skulls and spines

What can radiographic diagnosis of pregnancy allow determination of?

100% specific for presence of fetuses if after day 42 (when skull faintly visible)

MAY provide information on viability

What is the recommended timing of radiographic evaluation of pregnancy?

7-10 days prior to due date

What diet is recommended for the pre-partum dog?

balanced COOKED diet and increase over 22% crude protein in final month

ad libitum water throughout with ad libitum food in final week

supplements and probiotics are unnecessary if otherwise healthy

supplemental CALCIUM should not be provided

What activity is recommended for the pre-partum dog?

no strenuous activity in first 2 weeks or final 2 weeks

light-moderate beneficial during gestation

NO SWIMMING

What health/welfare is recommended for the pre-partum dog?

limit grooming to non-stressful, non-submersive methods

vaccines 2 weeks prior to proestrus OR wait until postpartum

Fenbendazole = 14 day prior, 2 days into, and 14 days postpartum

if product is untested in pregnancy/lactation, assume its harmful - whole list of things that are safe

How should owner's prepare the hours/environement for whelping?

box in quiet, low traffic area with 85-90 degree ambient temp

isolate dam/litter from novel dogs 3 weeks pre and post-partum

What whelping/rearing equipment should owners have on hand?

clean towels, water, and lubricant

mucus traps or suction bulbs

umbilical tape or clamps

scale and weight charts

+/- puppy identification

+/- milk replacer, bottles, feeding tubes

+/- 25G needles, stethoscope, hemostats

What are reliable predictors of whelping?

drop in rectal temperature

drop in progesterone

(others = loss of cervical mucus plug, nesting behavior, anxiety, tachypnea, rise in cortisol)