24a: Mare Management

Type of cyclicity in the mare

Seasonal polyestrus cyclicity

When do mares cycle

Summer

When are mares in a transition period

Spring and fall

When are mares in anestrus

Winter

When do we see a lot of anovulatory follicles in the mare

Fall transition period

Goal of reproductive management in the mare

• Maximize genetic potential

• Manipulate early foaling dates

• Efficient use of stallion services

Breed that wants to have foals as close to January 1st as possible

Thoroughbreds

Purpose of a BSE in a mare

• Get an idea of fertility

• Identify any issues

• Make a plan for how to improve fertility

Important part of history when evaluating a mare for breedin

• Age

• Breeding record

• Foaling history and viability

• Pregnancy losses

• Cycle regularity

Why might the cervix not match the uterus in old maiden mares

The cervix may be fibrosed

Maiden mare

Mare that was never bred and never carried a foal

Foaling mare

Mare that has recently given birth

Barren mare

Mare that did not conceive after being bred the previous year

Not bred mare

Electively not bred the prior year

Aborted mare

Conceived and lost pregnancy before foal was viable

Ideal BCS for a breeding mare

5-6/9

Breeds that may benefit from genetic testing before breeding

AQHA and warmbloods

Parts of an external genital examination

• Vulvar conformation

• Perineal integrity

• Vestibulovaginal seal

Appropriate vulvar conformation in the mare

Shallow angle (<0-10 degrees) and 2/3 of vulva below the pelvic brim

When should you check the vestibulovaginal seal

Before you palpate

Most important reproductive structure to palpate rectally and why

Cervix; tells you what stage in the cycle and what to expect on the ovaries

Classification systems for the cervix

A-C or 1-3 (closed = C/1)

How does the mare reproductive tract differ significantly from the cow

The ovaries are suspended by the broad ligament and there is no intercornual ligament

Ways to do a vaginal exam in the mare

Digitally or with a speculum

Mare cervix in diestrus

Tight and pale

Mare cervix in estrus

Pink and saggy

When is it easier to evaluate the cervix for tears

Diestrus

Methods for a uterine cytology

Cytology brush/swab or low volume lavage

How do you know if you have a good cytology sample

If you see endometrial cells

Gold standard for uterine evaluation in the mare

Uterine biopsy

What does a uterine biopsy tell us

Likelihood that a mare carries a pregnancy to term

What is a uterine biopsy looking for

Inflammation and fibrosis

Grades for uterine biopsy in the mare

• 1: good

• 2a

• 2b

• 3: very poor

T/F: we can treat uterine fibrosis

Nope

Purpose of hysteroscopy

Identify uterine lesions

When might a mare end up with blocked oviducts

If she has not been bred for a while and the ovulated eggs build up in the oviduct

What allows ovulated eggs to travel unhindered through the oviduct when the mare is bred

PGE₂ from an embryo

Most common ultrasound mode used to evaluate the uterus

B mode

How does frequency affect ultrasound image

Higher frequency provides better resolution but lower penetration

Most common ultrasound transducer for rectal ultrasound

Linear transducer