15. Obstetrics in Mares

What are THREE things that can cause prolonged gestation in the Mare?

- Accurate breeding dates

- Donkeys, mules, drafts tend to carry longer

- FESCUE

What is it called when the embryo pauses to hit a zone and the continues growing?

Embryonic diapause

What does fescue do to the gestation, mare , and foal?

- Longer gestation, larger foals, thickened placenta, agalactia in

mares

What is the ergot alkaloids that acts as a dopamine receptor agonists in fescue?

Epichloë coenophiala

T/F When dopamine increase, prolactin decrease

True

So if a mare is eating Endophyte-infected Fescue during gestation, what can this lead to?

a decrease in the amount of prolactin produced leading to agalactia the mare

What drugs can you use to treat a mare infected with Endophyte-infected Fescue?

Sulpiride or Domperidone

What is the MOA of Sulpiride or Domperidone?

dopamine antagonist

When should you remove the mare from pasture if there is a known fescue issue?

last 3 months of gestation

Friday before Memorial

Day...4:45 pm...phone

rings...

6 yr old maiden mare

Due to foal 2 wks ago

No signs that she is "ready to foal"

IF all of the above have been ruled out as causes, what do you do...?

1. Dispense oxytocin for the owner to give at home to induce labor

2. Admit mare to hospital and administer oxytocin to induce labor

3. Benign neglect

4. Emergency C-section since she is too far past her due date

Benign neglect (aka one of the treatments of prolonged gestation in the mare)

What THREE things should you do 4-6 weeks prior to foaling?

- Palpate to ensure she is still pregnant!

-vaccinate

- Open Caslicks if needed!!

Why should you vaccinate the mare 4-6 weeks prior to foaling?

so you can get levels of the antibodies into the cholostrum for the foal

How can you tell if a mare has a caslick because the sutures will usually not be there?

you will do a digital exam and there will be a pocket at the top

What degree perineal laceration occurs when skin and mucous membrane

tear at the dorsal commissure of the vulva?

1st Degree

What degree perineal laceration occurs when the tear extends deeper and involves perineal body and associated muscles of the vulva?

2nd degree

What degree perineal laceration occurs when there is a full thickness tear?

3rd degree

What is a RV fistula? How does it happen? When do you find it?

It is a hole between the rectum and vagina caused because the foals foot was pushed upward durning parturition. It usually isnt discovered until the mare is bred again

What are some prediction of parturition that can start 2-3 weeks prior to parturition but you can really tell 2-3 days prior?

Laxity of sacrosciatic ligaments; elongation of vulva

What should you look for to know that the mare will foal in about 24-48 hours?

Examination of udder for waxing

Stall-side kits monitor udder secretions of __ (+/- Mg) rise in secretions as well as

__ changes

Ca, pH

What do you need to be aware of in multiparous mares?

colostrum loss the foal may need colostrum or plasma when born (IgG)

When are most foals born?

evening or night

T/F Mares can delay parturition to some degree

True

What device is used when they sew an alert device into the vulva of the mare and it alerts the owner on a call?

FoalAlert® System

What is it called when the spinal axis of fetus in relation to that of the

dam?

Presentation

What is it called when the dorsum of fetus in relation to the maternal pelvis?

Position

What is it called when fetal extremities in relation to the fetal body?

Posture

What is a rapid, often violent process in the mare?

Stage II Eutocia (this is makes the mare different)

How long does stage II usually last?

20-30 mins

Most foals delivered in what presentation, position, posture?

- Cranial longitudinal, dorsosacral, head and forelimbs extended

- Approx 1 in 500 delivered in posterior presentation

What initiates the start of stage II?

chorioallantoic membrane breaking ( "water breaking)

What stage of foaling can you not see from the outside but lasts 1-4 hours and is mainly repositioning of the foal where it rotates dorsopubic → dorsoilial → dorsosacral position? What does this stage end with?

Stage 1, Ends with rupture of chorioallantois

What stage is expulsion of the foal and it is quick (20-30mins)?

Stage II

What happens in stage III and how long does it last?

expulsion of fetal membranes should be 1-3 hours after giving birth

Explain the Ferguson's Reflex

1. Fetus pushes against the cervix as it moves into the birth canal.

2. This stretches the cervix.

3. Cervical stretch sends signals to the hypothalamus.

4. The hypothalamus causes the posterior pituitary to release oxytocin.

5. Oxytocin causes stronger uterine contractions.

6. Stronger contractions push the fetus harder against the cervix → more stretching → more oxytocin.

Stage II the fetus passes through the birth canal. This elicits what TWO things to happen?

contractions and oxytocin release

T/F Mare usually lies on her side and periodically strains forceful.

True

When do the most forceful contractions occur?

when the head and shoulders are in the pelvis

T/F The mare need assistance so you may assist if needed; work WITH her

contractions

True

What is the 1,2,3 rule of stage III

The foal should be standing within 1 hour, nursing within 2hours, and the placenta should be expelled by 3 hours

Should you always examine the placenta?

yes, she said this about 100 times

Dystocia in the Mare is rare. Why is this the case?

the mare has a large pelvic canal and the presentation, position, and posture of the foal helps (Cranial longitudinal, dorsosacral, head and forelimbs extended)

T/F Dystocia in the mare is pretty chill and the cute lil baby usually is fine

False, Emergency for life of mare (foal usually dead)

If a mare has a dystocia, what is normally the cause?

Usually the result of abnormal fetal posture

- Neck and limbs longer

-Fetal oversize rare

What horse is at higher risk of a dystocia? Why?

Miniature horse due to the foals domed head

It is the Friday before Labor Day, at 4:45pm and you are presented with a mare dystocia. What do you do (besides cuss the mare out

- Evaluate dam and Tx accordingly

- Standing with sedation, if needed general anesthesia (xylazine/ketamine, gas, or triple drip)

- +/- Epidural

Why might an Epidural not be useful?

it takes awhile to show affects in the mare and her birthing process is usually quick

What are the THREE big differences in OB equipment between Equine and Bovine?

- length of neck and limbs

- mutation WITH CARE!

-NO CALF JACK!!!!

What are the TWO main sequelae of dystocia?

- RETAINED PLACENTA

- Nerve damage (paresis/paralysis of varying degrees)

What are some postpartum issues seen?

- Agalactia

- Tetanus

- Uterine prolapse

- Hemorrhagic event (Middle uterine artery)

T/F A foaling mare is an emergency

True