Receptivity, Fertilization, and Fetal Milestones - Exam 2

How large should the follicle be to breed a mare?

> 35 mm

How should the mare's cervix look when she is ready to be bred?

open

The mare should start showing signs of ___ when she is ready to be bred.

heat

The mare should be showing at least ___ out of 3 signs before being bred.

2

What does a cervix in estrus look like?

it will look like chewed bubblegum and be limp on the floor of the vagina

What is the range of the teasing scale?

1-4

What does a 4 on the teasing scale mean?

she is "hot" AKA ready to be bred

What is one way you can tease mares?

you can put a stallion in a stud box in the middle of a group of mares or walk a stallion through the mare barn

Where is the site of fertilization?

ampullary-Isthmic junction of the oviduct

How long can sperm last in the tract?

2-3 days

How long can an egg last in the tract?

6 hours

What happens to unfertilized eggs?

they get reabsorbed into the fallopian tubes

What is one of the most important causes of early embryonic loss?

post-breeding endometritis

What is endometritis?

inflammation throughout the uterus

When does embryonic loss usually occur?

within the first 20 days of gestation

How long does the embryo stay in the oviduct?

6 days

What must the embryo do after it leaves the oviduct?

it must traverse the entire uterus (ping-pong around)

What happens if the embryo does not traverse the entire uterus?

the mare goes into another cycle and loses the embryo

When does the embryo attach to the uterus?

day 17

Where does the embryo generally end up?

in one of the uterine horns

When is preg check 1?

days 14-18

What are you looking for during check 1?

check for pregnancy and twins

What should you do if the mare is open at check 1?

culture, biopsy, and flush the uterus and then rebreed day 19-20

When is check 2?

days 25-30

What are you looking for in check 2?

evaluate normal embryo development, HR, and twin recheck

When is check 3?

days 40-60

What are you looking for in check 3?

evaluating normal fetal development

When is check 4?

in the fall

What are you looking for in check 4?

confirming that the mare is still in foal

What are the four fetal milestones for days 12-16?

1. twin determination

2. evaluate CL

3. evaluate follicle status

4. evaluate endometrial edema

What are the two fetal milestones on days 24-27?

1. heartbeat can be detected

2. confirm absence of twins

What are the fetal milestones around day 35?

1. endometrial cup formation

2. eCG detected in blood

When do eCG levels peak?

day 60

When is eCG no longer detectable?

day 120

What happens by day 35?

more CLs develop to secrete progesterone and help maintain pregnancy

When can fetal sex be determined?

days 55-90

When can you easily palpate the fetus?

days 90-150