Horse Production Exam 3 (Part 2)

330-345 days (about 11 months)

What is the gestation length of a mare?

320-365

What is the day range of a mare's gestation within normal limits?

less than 320 days

How many days gestation is considered premature in mares?

Foal had normal gestational length, but appears as premature

What does dysmature mean?

behavioral assessment (tease mare with stallion), rectal palpation, ultrasound exam, progesterone level, ECG level, and estrogen level

How can you diagnose pregnancy in the mare?

Limited value for pregnancy diagnosis, low progesterone indicates mare is unlikely to be pregnant, valuable in determining if a pregnant mare is producing sufficient P4 to maintain her pregnancy

Progesterone test for pregnancy:

False diagnosis can be made if a blood sample is collected prior to day 35 or after day 120 of pregnancy. False diagnosis can be made if a blood sample is collected from a mare that lost her pregnancy after endometrial cup formation.

ECG test for pregnancy:

that endometrial cups are present and does not indicate true pregnancy status or fetal health

An ECG test can only confirm:

Equine chorionic gonadotropin

____ is produced from groups of specialized cells in the placenta called endometrial cups.

day 35-120 of pregnancy

ECG is only present in mares:

Uses estrone sulfate to diagnose pregnancy after approximately 60 days of gestation. Larger amounts of estrone sulfate are produced by the fetal-placental unit after day 90 gestation. Measurement after 3rd month gestation is useful to diagnose pregnancy.

Estrogen test for pregnancy:

estrone sulfate levels

Fetal death leads to a rapid decline in:

a combination of the three hormonal levels

If hormonal tests are used to detect pregnancy, use:

ultrasound

What is the most useful tool for early pregnancy diagnosis, identification of twins, and detection of uterine or ovarian problems?

day 14-16

What is the earliest positive detection of pregnancy via ultrasound?

14-16 .. can intervene

What is the earliest detection of twin pregnancy via ultrasound?

24-27

When can you detect viability on an ultrasound exam?

day 55-75

Fetal sexing via ultrasound exam can occur at its earliest on:

genital tubercle

When fetal sexing day 55-75, you ID for location of:

It is easier to ID fetal sex at ____ days gestation. 2 male organs can be seen

days 110-130

Which days of gestation are the most accurate for ultrasound sex determination?

Male foals sell for more than $ than females, can adjust insurance rates, and can determine which mares are taken to sales

What are the reasons for fetal sexing?

can result in abortion, highest occurrence in TB and draft breeds

Twinning in horses:

1) one fetus dies, the other may survive

2) If both survive >60 days, death of one fetus --> parturition problems

3) If both survive >60 days, fetal mummy and undernourished live foal at parturition

4) If both survive >60 days, death of one and abortion of both

5) If both survive >60 days, birth of two undernourished

6) If both survive >60 days, two healthy foals born = RARE

What are the possible outcomes of twinning in horses?

The vesicle appears as a translucent bubble. Visible as a black circle within a large grainy, gray background.

Describe day 9 of gestation:

Still mobile within the uterus, attached day 16-17 post ovulation. Embryonic vesicle is 1.5cm: black circle with caps on top and bottom

Describe day 14 of gestation:

Shimmering, flabby translucent bubble with a dark red embryo. Beginnings of animal features (a head with small eyes, a fleshy tail nub, 4 smallish buds), embryonic heart that is large enough to be seen

Describe day 24 of gestation:

Recognizable as a 4-legged critter. Blobby dome for a head, eyelids, rudimentary ears, ridges where nostrils will be, functional elbows and stifles. Vesicle is now 2.5 inches in diameter.

Describe day 40 of gestation:

Tiny ribs under skin, domed head that looks like a chihuahua, little triangles represent ears, hock and fetlock joints have developed. Slightly over an inch long, now the size of a pecan. graduated from embryo to fetus, last opportunity to view via ultrasound

Describe day 50 of gestation:

day 50

At what day of gestation does an embryo graduate to being called a fetus?

Clearly resembles a horse. Development of tiny hooves complete with soles and frogs. Fetus is about 2.5 inches long, is hairless, and about the size of a hamster.

Describe day 60 of gestation:

Fetal head and neck will be untucked. Sex is now visible. Fetus is about the size of a chipmunk.

Describe day 80 of gestation.

Ears are uncurling from its head, coronary band looks like little raised lines circling the tops of its tiny 1/4 inch hooves, 7 inch fetus is now the zie of a 6 week old kitten .

Describe day 100 of gestation:

Gains more than a pound every 10 days. Hair on chin, muzzle, and eyelids. Fetus is now the size of a rabbit.

Describe day 150 of gestation.

Fetus has quadrupled its weight in 30 days. Mane and tail hairs have appeared. It's about the size of a beagle.

Describe day 180 of gestation:

Fetus has whisper like hairs on its chin, throat, and muzzle. it is now the size of a small lamb.

Describe day 240 of gestation.

Fetus now looks like a goal, fine hair covers its body, it's about the size of a German shepherd.

Describe day 270 of gestation.

The fetus's lungs have developed, legs have strengthen, hair has coarsened, the fetus is done.

Describe day 320 of gestation.

kitten at 100, rabbit at 150, beagle at 180, lamb at 240, German shepherd at 270, and foal at 320

Describe size of fetus as gestation progresses:

placenta

What is the life support system for the developing offspring that develops around the embryo and is connected by the umbilical cord?

diffuse

What kind of placenta do horses have?

Thin, inner sac surrounding foal

What is the amnion?

The foal side of membrane

What is the allantois?

The mare's side of membrane that attaches to the uterine lining.

What is the chorion?

link between the fetus and the nutrient waste exchange structures of the placenta.

The umbilical cord is the:

2 umbilical arteries, umbilical vein, and urachus

What does the umbilical cord contain?

16x16 with solid walls

How big should foaling stalls be?

1-2 months before foaling so she has time to get accustomed and comfortable.

When should you put the mare in the foaling stall?

Straw because it doesn't cling to the mare's vulva or the foal

What bedding should be used?

Phone numbers readily available

Supplies for tail wrap

Reference sheet of "normal"

Flashlight

Paper and pen

Stethoscope

Thermometer and lube

Timer/watch

Diluted chlorhexidine solution

Disposable plastic cup

Disposable gloves

Blunt tip scissors

Umbilical tape or shoelace

2 Fleet Enema

Garbage bag

Clean towels

What should be in your foaling kit?

Security cameras, closed circuit TV, alarm systems

What are popular monitoring devices, check every 2 hours?

Measure the concentration of calcium in the mare's colostrum --> sharp rise before birth.

What does a foal watch kit do?

Evaluates the pH of mammary gland secretions, 6.5 or lower --> highly likely mare with foal within next 24 hours. Often combined with calcium secretion test

What does a mare foaling predictor kit do?

Remove Caslicks one month before due date and remove shoes

What is some mare prep you should do?

wash mare's udder with unscented ivory soap and place a tail wrap on her

When signs indicate that foaling is approaching:

Size and wright of uterus and fetus and changing hormonal levels

What is parturition triggered by?

Quickly and usually in the middle of the night. Most popular is midnight to 6am

When does parturition usually occur?

relaxin, prolactin, cortisol, estrogen, oxytocin, PGF2 alpha, and PGE2

What are hormones that increase at parturition?

Udder enlarges 2-4 weeks prior, muscles over croup and external genitalia soften 2 weeks prior, teats wax up 2-4 days prior, dripping colostrum 12-24 hours prior

What are signs of approaching parturition?

Problem, collect immediately and store

What does it mean when milk is streaming from the udder before foaling?

Possible impeding abortion, don't collect colostrum

What does it mean when a mare is leaking milk at mid pregnancy?

Sacrosciatic ligaments of pelvis relax, vulva swells and doubles in size, milk let down occurs, wrap the tail, groom and clean up

What happens 12-48 hours before birth?

1-4 hours

How long does stage one of parturition last?

obvious

Mare may not show ____ signs in stage 1

control

Mare has some _____ over stage 1

Mild colic signs, sweating, rolling, yawning, up and down

What does increased restlessness look like in stage 1 of parturition?

stimulates the fetus to reposition itself to dorsosacral position with front legs and head extended

Stage one of parturition:

the breaking of the chorioallantoic membrane and the fetus enters the birth canal

Stage one of parturition ends with:

placenta through the cervix

At the end of stage one, contractions force:

The cervical star

What is the weak spot in the placenta?

placenta (chorioallantois) ruptures at this point, resulting in expulsion of 2-5 gallons of fluid

When the placenta is pushed through the cervix:

dilated

At stage 2 of parturition the cervix is:

allows amnion, the fetal membrane surrounding the foal, to pass through cervix

Stage 2 parturition:

lay down

The mare will ___ ____ for final delivery, hard abdominal effort and uterine contractions.

2 feet and a nose with the front feet toes up. One leg is usually slightly ahed of the other followed by the muzzle

What should you see during stage 2 of parturition?

5-30 minutes, average is 10-15 minutes

How long does stage 2 take?

get the mare up and walk her

If malpresentation occurs during stage 2 of parturition:

When foal's hips clear vagina and straining ends

When does stage 2 of parturition end?

rests behind mare for 10-15 minutes still attached by the umbilical cord to the placenta, rest after exertion and transfer of placental blood. Foal muzzle should be free from amniotic sac

After stage 2, the foal:

Passage of the placenta, should be within 3 hours

What happens during stage 3 of parturition?

save the placenta

You should ___ ___ ___ in a bag or bucket of water prior to it becoming damaged. Need stop be inspected.

determine if pieces are missing, should only be one hole in one horn, nice healthy color, turn right side out to inspect the chorion

When inspecting the placenta you:

chorion

For placental attachment, which side is the mare's side?

allantois

For placental attachment, which side is the foal's side?

amnion

What is the name of the thin, inner sac surrounding the foal?

oxytocin

Milk let down is the result of the release of:

pituitary gland, contractions of uterus and manipulation of the teats

Oxytocin release comes from _____ stimulated by ____

Observe for normal behavior, assess vulva for injury/hemorrhage, assure high quality of colostrum is present, recommend vet exam

What does aftercare for the mare consist of after parturition?

Make sure fetal membranes aren't covering his muzzle, dip umbilicus with chlorhex several times within the first day. After the mare stands and has time to bond, then the foal can be assessed.

What does aftercare for the foal look like after parturition?

Heart rate of 60+ bpm, resp rate of 60+ bmp (higher than normal adult values)

At 5 mins after birth, a healthy foal will show:

a suckling reflex

Within 20 minutes after birth, the foal should have:

stand up

Within 1 hour, a foal should:

within 2-3 hours and nurse about once per hour

A foal should attempt to nurse:

meconium within 3 hours of nursing

A foal should pass:

first feces, frequent cause of colic in foal, requires enema

Meconium is:

disturb the mare, pull on placenta, cut umbilical cord, towel off mare, force mare to get up, force foal to nurse

We should not:

Foal should stand within 1 hour, nurse within 2 hours, pass meconium and pass placenta within 3 hours

What is the 1:2:3 rule of foaling?