Breeding Management - Equine Therio

Mare Reproductive tract

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Mares are seasonally polyestrous

• Breeding season is spring and summer (long day breeders)

• Multiple ovulations per year

Optimal birth season for foals

maximum survival occurs with birth in late spring and summer

4 seasons for the mare

Winter anestrus

Vernal transition period

Physiologic breeding season

Autumnal transition period

Winter anestrus

Centers around the winter solstice: December 21-22

Vernal transition period

Centers around vernal equinox: March 21-22

Physiologic breeding season

Centers around summer solstice: June 21-22

Autumnal transition period

Centers around autumnal equinox: September 21-22

Use of lights to increase day length early in spring

Vernal Transition and estrus occur sooner

• Especially helpful when breeding in the northern parts of the northern hemisphere

• When early foals are desired for production or racing reasons

• !6 hours total daylight daily - adding stall lights timed on from 6pm to midnight

Mare puberty

First ovulation

• occurs between 15-24 months - second summer of life

Estrous Cycle

The length of one ovulation to the next

• average cycle length is 21 days (range 18-24)

2 phases of estrous cycle

Estrus and Diestrus

Estrus

FOLLICULAR phase

• Mare is receptive to stallion during the 4-7 days prior to ovulation

Diestrus

LUTEAL phase

• Mare is not receptive to stallion from ovulation to beginning of estrus phase

  • reproductive tract prepares for pregnancy

Reasons for Mare BSE

• early estrus

• Determine if mare is fit to breed

• Maximizes chances of pregnancy and healthy foal

• Especially important with maiden mares, barren mares, older mares, mares with a history of loss

Mare BSE includes

• Identification - name, number

• Complete history - previous breeding? Any losses, previous pregnancy?

• Examination

  • Cardiothoracic auscultation?

  • Lameness?

  • Osteoarthritis?

  • Temperament?

  • Conformation

• Perineal inspection

• Vaginal exam

• Trans-rectal Palpation and ultrasound

• Uterine culture and cytology

• Uterine Biopsy

Mare - Perineal Inspection

• Vulva close to vertical

• Closely apposed

• No discharge, scars

• No gaping with gentle pressure on either side

Mare - Vaginal Exam

Speculum exam

• Visualize vestibule, vagina, external cervical os

Direct (digital) exam

• Evaluation of tears or adhesions

• Evaluation of fibrosis or incomplete dilation

Mare - Trans-rectal Palpation and Ultrasound

• Vagina (masses, air)

• Cervix (position, cysts, masses)

• Uterus (tone, size, fluid, cysts, pregnancy)

• Ovaries (size, shape, follicles, CL, cysts, masses)

Mare - Uterine culture and cytology

• Sterile swab of uterine endometrium (lining)

• Submit for bacterial culture

• Examine cells for cytology

Mare - Uterine Biopsy

Informative with barren, multiparous, older mares

Category I, IIa, IIb, III

Uterine biopsy category I

> 70% pregnancy

Uterine biopsy category II

30-70% pregnancy

Uterine biopsy category III

<10% pregnancy

Stallions of Seasonal long day breeders

• 20-50% more spermatozoa produced May-August than September-April

• Artificially advance the onset of long day photoperiod

What time of year do Stallions produce more spermatozoa?

May to August

Stallion - Puberty

• Occurs in the stallion by 18 months, may be as early as 12 months

• Increased muscle mass, increased jowl size, and male behaviors

• Sperm count increases with testicular size in mature stallion

Testicular Descent

Typically at birth or just after

• May be delayed until 2-6 months of age (still normal)

• Can descend between 6-24 months of age: cryptorchid

Cryptorchid

Where one or both of the testes fail to descend from the abdomen into the scrotum

Spermatogenesis

• Hormonal control trough testicles, hypothalamus, and pituitary gland

• Occurs in cycles/waves

• 57 days to create a mature spermatozoon

57 days

Days to create a mature spermatozoon

Thermoregulation of testes

• Function of scrotum and spermatic cord

• Fever over 104.9 leads to decreased concentration and morphology

  • occurs from 40×70 days after temperature elevation

• Prolonged exposure - 3 months to return to normal

Stallion BSE

• Identification

• Complete history

• Physical exam

  • Heart, eyes, lameness

• External genitalia

• Caution with tranquilizers

• Wash penis and prepuce

• Examine for masses

• Bacteriologic culture

• Other STD testing (EVA)

Stallion - External genitalia exam

• Scrotal width, consistency

• Penis - erect examination

Acepromazine

Tranquillizer not typically used with Stallions

Semen Evaluation

• Volume

• Motility (total progressive)

• Velocity

• Concentration

• Morphology

• Longevity studies in extenders

Stallion on-site breeding

Pasture Breeding

Hand breeding

• Serial

• Veterinary

Pasture Breeding

Turn out mare and stallion together

• limited information

Hand Breeding - Serial

Breed every other day from Day 2 estrus

Hand Breeding - Veterinary

Breed prior to ovulation

Stallion off-site breeding

Stallions are collected every other day

• Semen is extended, cooled and shipped

Mare is monitored via ultrasound examination

Insemination

Post-Breeding examination

• Ovulation

• Fluid clearance

When should insemination occur?

Between 12 hours prior and 48 hours post-ovulation; ideally within 12 hours of ovulation

Day of first ultrasound

14-16 days post-ovulation

Ultrasound exams

14-16 days - looking for twins

25-30 days - heartbeat

45-60 days - sexing

Pregnant Mare Housing

• Separated

• Moderate exercise

• Routine care

Pregnant Mare vaccinations

• Rhinopneumonitis (months 3, 5, 7, 9)

• All spring vaccines boostered at 4-6 weeks pre-foaling

Pregnant Mare Deworming

Safe, administer based on FEC, exposure, and at foaling

Pregnant Mare Nutrition

• 65% foal birth weight gained in last 3 months of gestation

• Lactation - highest nutritional requirements

• Do not let clients overfeed!

Routine Care for Pregnant mares

• Ultrasound exams

• Housing

• Vaccinations

• Deworming

• Nutrition

Preparing for Parturition

Suitable location for foaling

Udder cleansed with mild detergent

Wash perineal region

Caslicks removal

Suitable location for foaling

• 4-6 weeks prior to due date

• Clean, dry, protection against elements

• 14 ×16 foot stall with straw over shavings

Caslicks

Surgical procedure where the upper part of a mares, vulvar lips are partially stitched closed to create a tight seal, preventing air and fecal cntamination from entering the reproductive tract.

• This must be cut open before foaling!

Post-Partum changes

Waxing of teats

Milk Secretions

Vulvar and pelvic ligament laxity

Udder enlargement

Waxing of teats

Early colostrum formation

Typically 1-4 days prior to foaling

Milk Secretions

• Milk changes from thin straw-colored to milky white

• Yellow-orange as colostrum forms

Udder enlargement

Typically significant growth in final 2 weeks

Monitoring Parturition

• Sleep in the barn

• Video

• Sound monitors

• Various foal alert systems

  • foal-alert system

  • birth-alarm system

Stage 1 of Parturition

• 30 minutes to 4 hours

• Restlessness and signs of colic

• Uterine contractions

• Fetal repositioning

Proper fetal position

Anterior longitudinal dorsalsacral with head resting on extended metacarpals

Stage 1 - Preparation of the Mare

• Clean udder

• Tail wrapped

• Perineal area scrubbed

• Remove extraneous people - helps mare relax

Stage 2 of parturition

• Fetus passes into birth canal

• Mare lays down, strains in lateral recumbency

• Rupture of the chorioallantoic membrane

• 20-30 minutes for this stage

  • steady progression

  • Maximum time - 70 minutes

Rupture of the chorioallantoic membrane

Embryonic membrane

Order:

• Extended legs

• Nose

• Head and shoulders

• followed by hips

The three P’s

Presentation

Position

Posture

Presentation

Relationship of the long axis of the foal to the long axis of the mare

(longitudinal)

Position

Relationship of the dorsum of the fetus to the maternal pelvis

(dorsosacral)

Posture

Relationship of the fetal extremities to the fetal body

(had resting on extended metacarpals)

Stage 3 of parturition

Delivery of the placenta/fetal membranes

• 30 minutes to 3 hours

• Tie up above mare’s hocks

Beginnings of uterine involution

• Decrease in uterine size occurs within 12-24 hours

• Uterine fluid mostly expelled by 24-48 hours

Uterine Involution

Shrinkage of the uterus back to its normal size after birth

Post-Partum exam - Mare

• Cleanse udder

• Ensure adequate milk production

• Colostrum

• Examine perineal area

  • ensure vulva and anus intact

  • Evaluation bruising and edema

  • Rectovaginal fistula

Post-Partum exam - Placenta

• Lay out on clean floor

• Examine inside-out and right-side in

• Can fill with water

• Critical that entire placenta, including tips of horns, is present

What is this?

An intact placenta

Foaling complications

• Red Bag

• Dystocia

• Retained placenta

Red Bag

Premature placental separation

• Chorio-allantois must be ruptured immediately

• Assisted delivery — foal will rapidly become hypoxic and anoxic

• Associated with placentitis, twinning, inappropriate induction methods, unknown causes

Dystocia

Lack of progression in first or second stages

Medical emergency

Fetal cause of Dystocia

Typically some sort of malpresentation

Maternal causes of dystocia

• Inadequate pelvic size or pelvic abnormality

• Rupture of prepubic tendon

• Abdominal hernia

• Uterine inertia

• Uterine torsion

• Cervical scarring

Uterine inertia

Failure of uterus to contract effectively during foaling, leading to prolonged labor or failure to pass the foal

Retained placenta

Fetal membranes not expelled within 3 hours

Most common post-partum complication

Complications of Retained placenta

• Metritis

• Septicemia

• Laminitis

• Mare death

3 Function genital seals of the Mare

The vulva

The vulvo-vaginal constriction (vestibular seal)

The cervix