Equine Repro Notes

Mare Anatomy

Why Study Anatomy?

Importance of anatomy and physiology comprehension:

Determining when there is a problem
Horse Selection
Breeding/Cycling

Function of Reproductive Tract

Release of ova
Maintain conceptus through gestation
Deliver newborn
Nourish newborn

Organ Groups

Fundamental Structures

Ovaries
Oviducts
Uterus
Cervix
Vagina
Vulvar labia
Mammary glands

Regulatory Structures

Pineal gland
Retina
Hypothalamus
Pituitary gland

Vulva

Three Structures

Labia
- External Opening, Lips of vulva
Clitoris
- Place where bacteria likes to grow
Vestibule
- Secretary glands/Mucus glands that help lubricate reproductive tract

Function of labia and vulva

Protect

Position Important

Lips: Tight seal, keeps bacteria and manure out of the body
Angle of vulva: Vertical
- Position: over 50% below pelvic rim from the point of butt
Caslick procedure: remove a little bit of tissue around labia and suture it back up to try and keep pregnancy a little bit cleaner

Vestibule and Vagina

Vestibule: 4-5”

Secreting mucus to help with lubrication

Vagina: 6-8”

Highly elastic
No secretions

Cervix

When in heat will get soft and loose, will sink lower in body when trying to AI

Function:
Secretory: Think mucus
Shape changes in response to hormones: Changes the feels and consistency of cervix when in and out of heat

Uterus

Two horns and body
Suspended via broad ligament
- Attachment = Mesometrium
  - Attaches to the dorsal surface
3 barriers of protection
- Endometrium
  - Changes throughout cycle
  - Creates uterine milk as well as for the fetus and placenta attachment
  - Secretions
Perimetrium
- - Outermost lining, attached through connective tissue to the broad ligament
Myometrium
- - Contains muscle; helps with contractions

Oviducts

Three sections

Infundibulum
- Where sperms is going to come in
Ampulla
- Where oocytes will meet sperm cells
Isthmus
- Going to catch oocyte
- Where sperm cells will remain
Uterotubal junction
- Muscular sphincter that selectively allows embryos, but not unfertilized oocytes to pass into uterus
  - Unfertilized oocyte remain in oviduct - fertilized egg will move into uterus 4 days post ovulation

Ovaries

Location: sit in between 3 or 5th lumbar vertebra

Different sections of the broad ligament will hold this up
- Mare ovary is “inside out”

The Ovary

Functions: produce and house oocytes

estrogen and progesterone produced

Transient components: CL and follicles

Tissue types: Medulla and cortex

Medulla provides structural support for the ovaries
Cortex is where the germinal cells will be houses
- Will not ovulate if there is a CL present

Broad Ligament

Supports and suspends the repro tract

Also contains blood supply and brings through nutrients

Mesovarium

Supports the overy

Mesosalpinx

Supports the uterus

Mesometrium

Supports the

Mammary Gland

Four quarters

Each tit have 2 quarters
Milk produced in alveoli
Mammary development minimal until late gestation
- They do not hold very much milk in their tit cistern/gland cistern
3-4 weeks before due date mare will start to develop an utter

Reproductive Status

Maiden mare
- Never had foal before/Never been bred
Barren mare
- Not pregnant this year/having issues getting bred but has had a foal/bred before
Slipped mare
- Was confirmed in foal but lost the pregnancy early on
In foal mare
- Is pregnant and carrying foal
Open mare
- Didn't bred this year

Leptospirosis

Bacterial infection
Zoonotic
- Signs: Feber, depression, loss of appetite, abortion, uveitis
Diagnosis: Blood test
Prevention: Vaccination, best management practices

Estrous Cycle

Estrous Cycle gestation

Estrous cycle consist of a series of predictable reproductive events beginning at estrus and ending at the subsequent estrus
Provide females with opportunity to copulate and become pregnant
- Anestrus = a period without estrous cycles

Seasonal Anestrus

Gestation ~340 days

Prevent females from conceiving during periods of the year when survival of the developing embryo and neonate would be low
- Transitional period:
  - Erratic and unpredictable
  - Recommended not to breed mares at this time

Estrous Cycle

21 days ovulation to ovulations

Estrous Cycle Phase

Follicular Phase:

Follicle grows to dominance
- Estrogen (estradiol)
Follicle will ovulate
Follicle changes, anatomically and functionally

Anatomical changes:

Cells reorganize
- change what they are doing once they are ovulated

Functional changes:

Shift in hormone production
- Stop making estrogen and start making progesterone

Luteal Phase:

Corpus luetum
- Corpus hemorrhagicum
  - 2-3 days to see this before it turns into a CL
- Corpus Albicans
  - If not bred will turn into a scar (regress)
If bred: CL stays around to help maintain
If open: CL will regress into a corpus albican
- Uterus releases prostaglandin F2a (causes the CL to regress)
  - Lutelalizis: technical term for the regression of the CL

Estrous Cycle Stage

Stages:

Follicular

Proestrus
- Receptive for 5-7 days to stallion
Estrus

Luteal

Meetestrus
- Transition between estrogen to progesterone
Diestrus

Proestrus

Begins when progesterone declines as a result of luteolysis
- Follicles are recruited and tract prepares for the onset of estrus
  - Endocrine transitions

Estrus

Estradiol concentrations are high
- Onset of sexual receptivity is gradual, culminating with standing estrus
Notaceable behavior/anatomical changes
- Relaxed cervix
- Increased locomotion, urinating/winking, general nervousness
- Standing behavior: “breaking down”

Metestrus

Begins at ovulation ends at fully functional CL
Transition to a period of progesterone dominance
- Luteinization: follicle undergoes cellular and structural changes to become the CL
  - 2-5 days before C: produces high levels of P4

Diestrus

CL is fully functional and P4 secretion is high
- Longest stage of the cycle
  - P4 purpose:
    - Ends when CL is destroyed (luteolysis)
    - No sexual receptivity
    - Closed, pale cervix located high

Follicles

Oocytes stored in follicles
- Zona pellcida
  - Acellular structure surrounding oocytes
    - Protection, encasing membrane

Types of follicles:

Primordial
Growing
Antral
Graafian
Anovulatory
Regressing
- Microscopic unless selected to grow

Cell Types

Granulosa Cells → inside
- Respond to the follicle hormone FSH
- Produce estrogen/estradiol
Theca Cells → outside
- Structural support for follicle → “connective tissue”
- Produce progesterone
Cumulus
- Helps with cell fertilization

Follicle Size for Ovulation

~40-50mm cell ovulation depending on the mare

Some smaller and some larger

Corpus Luteum

Cellular changes
- Granulose cells become large luteal cells producers of progesterone
- Theca cells become small luteal cells

Endocrinology of Reproduction

Functions of the Endocrine System

Collection of Organs that produce hormones
- Regulates
  - Metabolism
  - Growth and development
  - Tissue function
  - Sexual function
  - Appetite
  - Sleeping and waking cycles

Basics of the Endocrine System

Hormones
- Secreted by glands
Glands
- Going to produce the hormone
  - Ex: Uterus, testes, hypothalamus
Target tissues
- When the hormones have its effect
Receptors
- Located in the target tissues
Feedback loops
- A stimulus

Types of Action

Endocrine
- Secreted by circulation to secrete its response
Paracrine
- Target near by tissues and or cells
Autocrine
- Hormones that secrete on its self

Components

Hypothalamus
Pituitary gland
Adrenal gland
Thyroid
Pancras
Gonand

Endocrine Regulatory Structures

Pineal gland
- Produce melatonin
- Responsive for changes in daylight
Hypothalamus
- Secretes GnRH (Gonadotropin releasing hormone)
  - GnRH stimulates the release of the pituitary glands
Pituitary gland
- Anterior pituitary
  - Produces oxytocin
- Posterior pituitary
  - Produces FSH (follicle stimulating hormone)
    - Ovary
  - Produces LH (luteinizing hormone)
    - Follicnes
      - E2
    - CL
      - P4

Back up to oxytocin

PGf2a regresses CL

Hormone Classification

Amine hormones
- Small
- Has nitrogen on them
  - Components: Amino acid with a modified group
Peptide/protein hormones
- Bigger than an amine hormone
- Chain of amino acids
  - Components: aminoacids
Steroid hormones
- Derived from cholesterol
  - Components: Testosterone, progesterone, and estradiol

Peptide/Protein Hormones

Water soluble
- Examples: Insulin, growth hormone, ADH, Gastrin, CCK
Stored in vesicles prior to release

Steroid Hormone

Made from: Cholesterol
Fat (lipid) soluble
- Examples: Estrogen, Testosterone, Cortisol, aldosterone
Made on demand

Amine Hormones

Made from tryptophan or tyrosine
Most are water soluble
- Examples: thyroid hormones, (nor) epinephrine, serotonin
Stores in vesicles prior to release

Fat or Water Soluble?

Determines travel through the blood and interaction with its receptor on the target cell
Determines the mechanisms of action in the target cell

Movement through the Blood

Water soluble: generally “free”
Fat soluble: bound to a carrier protein

Hormone Receptors

Bind to hormones and elicit and intracellular response
- Nature of response specific to receptor type
Tissue specific receptor expression
Number of receptors on/in cell affects the sensitivity of that cell to the hormone

Hormones secreted in the Brain

Hormones from Uterus and Ovaries

Reproductive Endocrinology

H - P - G axis
Hormonal feedbacks

Control of secretion and production

Positive and negative feedback loops
Unbalance = reproductive problems

Hormone Therapy in Mares

Why do we need to manipulate estrous?

Try and increase pregnancy rates
Expensive
Only have stallion at certain times
Born earlier for competition

How to manipulate estrus?

Photoperiod → melatonin being produced
- Melatonin secreted during hours of darkness
- Ambient light - first cycle ~ March/April
- Stimulatory artificial photoperiod - earlier ovulation
Artificial lighting
- Alters photoperiod
- Begin Dec 1st → ovulate mid Feb
  - 60-70 days to get to begin ovulating regularly with manipulation of lights
- 100 - 200 watt bulb in 12 x 12 stall
- Goal: Expose them to 16 hours of light and 8 hours of darkness
  - Preferably in the evening
- Timers: off at 11pm
  - - Light Masks
      - LED blue light

468 nm wavelength

One eye

Hormonal Manipulation of Reproduction

Control of Ovulation

Why:
- Flush oocytes/embryos
- Breeding
- Timed ovulation
GnRH and hCG given
- hCG: is going to act similar to LH
  - Ovulate 36-48 hours after hCG is given

GnRH

Peptide hormone - 10 AA
GnRH agonist - Deslorelin
- Implant: in the mucosa in the vulva will include the LH causing the mare to ovulate
- Injectable: 85-95% of mares with a follicle >35 mm ovulate within 48 hours

hCG - Human Chorionic Gonadotropin

LH - like activity
Requirements for hCG to work
- Follicle >35mm
- Uterine edema
- Ovulate ~ 36 hours after treatment in 80-90% of mares

Lutalyse - Prostaglandin

Prostaglandin secretion is pulsatile
Administration of exogenous prostaglandin
- Side effects: sweating, abdominal cramping, diarrhea
Typical use: Short cycling mares
- Minimum of 5 day post ovulation to give luteolyse
  - We do this to make sure we have a mature CL to be able to regress
3 fates of prostaglandin administration:
- 1. If the mare has a follicle she might ovulate before she comes into behavioral estrus
- 2. You can cause the CL to regress and the dominate follicle will ovulate just like predicted (3-4 days before she would have naturally)
- 3. Have a growing follicle however it might start to regress

Short Cycling a Mare

To be used:
- Syncronization
- Getting multiple pregnancies in a year
Natural ovulation
Develops a functional CL
Give Lutalyse 6-8 days post ovulation

FSH - Follicle Stimulating Hormone

Used to recruit multiple follicles
FSH administered twice daily
- 5-7 days after ovulation when largest follicles is 20 mm

Superovulation in Mares

5-7 days post ovulation of FSH
7-9 days post ovulation of luteolyse
- Continue FSH twice a day for 3-5 days until follicles reach 35 mm
- Administer hCG
Breed mare
Collect embryos 7-8 days later, implant into recipient mares

Progesterone - Altrenogest

Produced by CL and placenta
Potent negative feedback on LH
- Typical use: performance horses to keep them out of coming into heat
  - Maintain pregnancy in pregnant mares
Suppressing estrus

Protocol for Early Breeding

Dec 1: Increase lights to 16 hours a day
Jan 2: Being teasing with stallion
Jan 14-25: Palpate for CL or follicles
Jan 26 - Feb 4: If follicles present, daily regulate
Feb4: Treat with luteolyse (PGF2a)
Feb6-10: Breed when follicle >35mm or every other day when in estrus

Stimulating Transitional Mares

sOne ore mare follicles >20mm
Administer lowdose GnRH (deslorelin) bidaily, IM
Discontinue when one or more follicles >35 mm
No therapy for 24 hours
Administer hCG

Induction of Times Ovulation

Uses:
- 2 doses of Semen
  - Desolrelin 8 am or hCH at 12pm
  - AI evening after dosing
  - Ovulation at midnight
Requirements:
- 1 dose of semen
  - Deslorelin 8 om
  - Ovulation 12pm
  - Inseminate post ovulation
- hCG or Deslorelin

Early Pregnancy

Fertilization

In the ampullar isthmic junction

Activities in the mare
- Mare needs to ovulate
  - Sperm ejaculated directly into the cervix
Activities in the sperm
- Sperm have to go through capacitation to be able to fertilize the egg
- Happens through the mares repro tract in the isthmus
  - 4 hours for sperm to make it to oviduct

Capacitation

Fertilization

Embryonic Development

Cell division begins within 24 hours of fertilization

Morula > 32 cells

Blastocysts = differentiation begins (all in the oviduct)

Trophoblast cells: become the placenta, arranged along the outside
Inner cell mass: become the fetus/embryonic cells

Enters uterus at around day 5 or 6

In the estrus cycle the CL isn’t “ready” until day 5 or 6 of her cycle

Early Embryonic Development

Gastrulation occurs by 14 days

Differentiation
Form germ layers
- Endoderm: form internal layers
  - Lung cells, thyroid cells, digestive cells
- Mesoderm: Middle layer
  - Support system
- Ectoderm: External layer
  - Nervous system and skin cells

Movement of Conceptus

Movement in uterus

Prevents release of PGF2a
- Day 16 or 17 (maternal recognition of pregnancy)

Endometrial Cups

Equine chorionic gonadotropin (eCG) very high in early pregnancy

Day 28: Endometrial cups form, invade uterine endometrium
Day 55-70: maximum size
- Function: produce a hormone called eCG that is going to act like LH
  - Encourage formation of a secondary CL on the ovaries
Cups destroyed by 100-140 days gestation (regress)

Placental Development

Two membranes

Chorioallentosis: Chorion + Allantois = the placenta
- Uterus side
Allantoamnion: Allantosis on outside and amnion inside, very vascularized
- Foal side

Placental Features

Attachment to Endometrium

Microcotyledons

Fundamental unit of fetal maternal interface
- Specialized chorionic villi

Types of Placentation

6 layers between the maternal and fetal blood
- Maternal circulation is poor, only supports one fetus
- All of the placenta interfaced with endometrium
  - Top image: Horse
  - Middle: Dog
  - Last: Humans

Equine Placenta: Mend

M - Microcotyledonary
E - Epitheliochorial
- Multiple layers why it can peels
N - Nondeciduate
- Do not bleed or lose any tissue from uterus when foals
D - Diffuse
- Covering the entire placenta

Fetal - Placental Hormone Production

Progestogens

P4 and P5
- Come from the placenta especially surge when they are in the end of pregnancy
Helps with shedding

Estrogen

Encouraging or promoting blood flow to the placenta
- Mares don’t have get blood flow
In the fetus the gonads are going to produce DHA that will go to the placenta and then the placenta will produce estrogen

Relaxin

Maintain pregnancy
Towards the end of pregnancy if helps relax the pelvic ligaments for the mare to be able to foal out
- Produced by the fetal, placental unit

Function of the Placenta

No mining of blood occurs

Selective transport of nutrients and waste products between mare and fetus
- Gasses: gas exchange with fetus
- Nutrients
- No transfer of immunoglobulins in mares
  - Not just a permeable membrane

Middle Pregnancy

Middle pregnancy: through 7 months

Good quality hay, balancer pellet or light concentrate
- Benefit from moderate riding or exercise

Ultrasound/Pregnancy Check

Day 2 after breeding – see if she has ovulated

Day 14 - 15
- If conceptus not seen:
  - Tease the mare
  - Rescan in a couple of days
- If conceptus is seen:
Twins??
- Abort 7-8 months
  - Factors:
    - Breed
    - Repro status
    - Age of mare
    - Lactation status

Presence of twins in opposite horns → the one twin will be pinched

Regu mate and flunixin (banamine) given twice or three times a day for three days
Ultrasound on day 4 post pinch

Twins on top of eachother or near eachother

Scan in one or two days
Pinch if separated
- If haven't separated will give PGF2a and start over

Pregnancy Check Continued

Day 22 - 28

Increased uterine tone, tight cervix
- Regu mate if tone is not normal and check blood P4

Day 60 and 90

Make sure mare is still carrying pregnancy
- Fetal sexing can also happen during this time
  - Also can to 120-160 trans abdominal

Pregnant Mare Urine (PMU) Mare Industry

Production of hormone therapies for menopausal women

Estrogen
- ~1300 mares, QH, Paints, Appys, Drafts, Thoroughbreds
Ranches contracted by Pfizer near Brandon, Manitoba, Canada
- North American Equine Ranching Information Council (NAERIC)
  - Incentives for showing/racing

Care of the Pregnant Mare/Neonate

Nutrition

Maintain BCS of 6-7: Once she reached lactation she will struggle to meet nutritional requirements
- First 8 months:
  - Good quality forage and balancer for her food
- Last 3 months:
  - Increase mares nutrient intake
    - Good protein sources/quality → amino acid
      - Soybean meal
  - Increase energy
    - Form of hay or concentrate feeds
  - Good intake of Calcium and Phosphorus
    - Ideally 2:1 ratio

Nutrient Requirements

Nutrition Continued

Forage based diet
- Forage first!
  - Alfalfa mixed hay
Fortified concentrate feed
- Best option for mare and foal specific feed
Free choice salt
Free choice water

Parasite Control Reminders

Use fecal egg count, treat accordingly
Storngyloides Westerii (threadworms)
Deworm within 2 months of foaling
Pasture management

Housing Considerations During Pregnancy

Ideal: Shelter from the elements

Fields open areas

Biosecurity

Avoid having pregnant mares around sick, young, or traveling horses

Changes close to foaling

Will self isolate

Pasture concerns:

Tall fescue
- Can cause a golactia and increase risk of dystocia
  - Toxin is still active if mowed as well
Get mare accustomed to where she is going to foal

Vaccinations for the Pregnant Mare

Purpose:

Core Vaccines
- Tetanus
- WWE
- EEE
- Rabies
- WNV
  - Timing: 4-6 weeks give other than rabies give that one after she foals
    - Not recommended during pregnancy
Reproductively important
- Equine herpesvirus 1 (EHV -1)
- Equine viral arteritis (EVA)
- Rotavirus

Equine HerpesVirus

EHV-1
- Neurological form
- Respiratory disease
- Abortion and neonatal health
EHV-3
- Venereal disease
  Affects external genitalia
  - Causes abortion in pregnant mares
EHV-4
- Nonfatal upper respiratory disease
- Seen in foals

Equine HerpesVirus-1

Signs

Incubation period typically 4-6 days
Biphasic: Fever day 1 or 2 and again on day 6 or 7
Respiratory signs: Nasal and ocular discharge, not much coughing
Neurologic signs: Rapidly progressing, incoordination, limb weakness, head tilt, inability to rise
Reproductive signs: Abortion between 7-11 months

Contagious

Direct horse to horse
- Indirectly through contaminated physical objects
Survives up to 7 days in the environment
Easily killed by disinfectants

Protection

Vaccination: Equine Rhinophounagalis vaccine
- Best management practices:
  - Biosecurity practices
  - Clean equipment
  - Take care of mares before other horses
- 3 dose series for mares: 5,7, and 9 months of gestation

EVA

Contagious disease

Abortions
Death in young foals
- Stallions can be long term carries → can cause infertility
Respiratory secretions
Veneral
Indirectly
In utero

Signs

- Fever
- Swelling in legs, scrotum, sheath in stallion
  - Breeding stallions should be tested
- Swelling in mammary glands, and around eyes in mares
- Anorexia and depression
- Nasal discharge
- Abortion
- Death in foals
- May show no signs some

Diagnosing:

Vaccine: There is a vaccine that can be given to a mare than is going to be bred to a stallion that is a carrier of this disease

No proven therapeutic means of eliminating virus form carries

Best management practices

Biosecurity
Testing mares and stallions
Checking sperm/blood
Vaccinate stallions
Known carrier isolate them

Rotavirus → Zoonotic disease

Virus damages SI villi

Highly Contagious
- Environmental contaminations
- Fecal oral route
- Indirect
Best management practices
- Isolate infected foals
- DO NOT spread manure on pastures
- Disinfect stalls
Biosecurity: washing your hands and changing your clothes, boot wash, keeping separate equipment
Signs
- Diarrhea
- Lethargy
- Anorexia
- Distended abdomen
  - Infected foals shed virus in feces for up to 10 days
Protection
- Vaccination: 3 dose series for pregnant mares 8,9,10 months
  - Only effective if foal receives an adequate amount of colostrum and absorbs sufficient anti rotavirus antibodies

Preparing for Parturition

Prep for Parturition

Herd management
Move to foaling premise ~ 4 weeks. Prior to expected foaling date
Prep stalls
Observation!!!

Gestation Length

Average 340 days, 320-360
305 to 320 days is considered premature
- < 305 days is considered an abortion
Gestation length > 365
- Foals can get dismature when the mares go longer than 365, foals can get muscle atrophy, and crooked limps, and placenta can start to go “bad”
- Mares usually follow the same pattern every year typically
Influencing factors
- Seasonal affects: mares that foal early in the year they tend to hold pregnancy about 10 days longer
- Sex of foal: Fillies have about an average 3 days earlier gestation versus colts they will go later
- Body condition: thinner mares will have their baby later in gestation

Physical Changes – Nearing Parturition

Mammary gland development
- Begins around 4-6 weeks
  - Madin mares may be a little less pronounced in the way the bag grows
- Engourged
  - Less than 7 days of foaling
- Waxing
  - Not all mares develop wax
- Drip milk
  - In the days leading up to foaling
- Change in electrolytes of colostrum
- Record daily udder scores!
  - Morning and Evening

Udder Scores

Score 1: Little to no udder development
Score 2: Developing udder, not tight, teats not full
Score 3: Full, tight udder with filled teats
- Amber or wax

Physical Chances Continued

Pelvis
Vulva
Swelling of vulva
Vaginal discharge
Belly drops
Tailhead
Reduced feed intake or refusal
Behavior changes
- Starting First Stages of Labor
  - Colicky, frequent urination

Mammary Secretions

Electrolyte changes
pH decreases
- 7.4 plus 12 hours before foaling
  - Will drop about 6.4 -6.2 before mare foals

Predicting Foaling via Colostrium

Using 400mg/dl Calcium cut off:
- If >: 90% certain that mare will foal within 24h
- If <: 98% certain that mare will not foal within 24h
pH if decreases to 6.4
- 97% certain that mare will foal within 24h
- If >: 99% certain that mare will not foal within 24h

Observing Foaling

Night watch person
Cameras
Foal alert system
Halter monitors

Normal Parturition

Initiation of Parturition

Fetal placental signaling triggers parturition
- Fetal HPA axis
- ↑ Fetal ACTH, ↑ Fetal cortisol
  - Effects:
    - Starting the beginning stages of labor
    - Starting the hormone changes
Progesterone withdrawal – removes uterine quiescence
Increased estrogens
- ↑ Myometrial contractility, ↑ Oxytocin receptors, ↑ Prostaglandin production, Cervical softening
Prostaglandins and oxytocin – Positive Neuro Endocrine Loop
- PGF2a
  - Stimulates uterine contractions
- Oxytocin – Posterior Pituitary
  - Ferguson reflex
- Key Concept: Parturition initiated by the fetus, not the mare

Stages of Labor

Stage 1: Pre Devilery, Positing the foal
- Starting contractions → Ends with water breaking
- Foal getting into position
  - Mare might begin to pase, colicky signs, biting at belly
- Be calm and quiet! → wrap top portion of tail
Stage 2: Delivery
- Feet should appear first
  - Check proper delivery position
  - Soles of feet facing mares feet
- Nose
- Delivering the chest
  - Timeline: 30 minutes
    - Rest post delivery
    - Umbilical cord breaks
      - How to help (if it’s safe):

Move membrane off of foal if still on there

Check for foal to be breathing

Possibly towel dry foal

Move foal towards front of mare if still laying down

Stage 3: Passing the Placenta
- <1 hour
- >3 hours = retained placenta
- Save placenta for evaluation
  - Never pull placenta out of the uterus

Proper Presentation

Check for 2 feet and nose position
Front feet – soles down
- Call the vet if it's any different!
Can get mare up/down

Placental Examination

Always exam post foaling

Post Foaling Procedures

Tire up amnion
Banamine
- If they are still uncomfortable
- Give after placenta is given
Wash Udder
Strip some colostrum to test
Naval dip as soon as breaks and stops bleeding
- Dilute chlorhexidine solution (0.5%)
- 2x/d for first 48-72 hours

Foaling Emergencies

Red Bag - CALL VET
- Rupture membranes immediately
- Deliver foal as soon as possible
Rectovaginal perforation occurs
Mare foals while standing
Excessive bleeding from mare or mare gums pale or purple
- Should be no bleeding after foaling

Mare Management Postfoaling

Maidens - Give banamine
No concentrate for 12 h
Check temp
Excessive vaginal discharge
Hemorrhage concerns
Mastitis prevention if foal is sick
Turn out it is important!

Abnormal Parturition

Dystocia

Anything that is not normal foaling

Long labor
Mal presentation
- Stage 2 of labor more than 30 minutes

Medical emergency

4-14% of all equine births
Early recognition and early successful intervention is critical for foal survival
The ultimate goals
- Survival of the mare
- Survival of the foal
- Maintain mares fertility

Dystocia and Foaling Times

93% between 9:00pm and 8:00am

Obstetrical Intervention

For each 10 minute increase in stage 2 of labor beyond 30 minutes
- !0% increased risk of foal born dead
- 16% increased risk of foal not surviving

Causes of Dystocia

Fetal Causes → More Common

Abnormal orientation of fetus
Developmental abnormalities
- Contracted tendons
Dead or sick foals

Maternal Causes

Uterine inertia → More common
- Mare stops pushing
Narrowing of birth canal
Pelvic fracture
Anatomic defect

“On Farm Obstetrics”

Key Components:

Experience
Training
Preparation
- Equipment, supplies
- Emergency plan
  - Relevant factors:
    - Proximity to vet clinic and or surgery suite
    - Experience of staff
    - Limitations of staff
    - Understanding the situation
    - Call for assistance if in doubt

When to Call for Assistance

If there has been no progress toward delivery after 15 - 20 minutes
Progress abruptly stops
If mare becomes painful or is in shock
If you detect a significant problem
If you are unsure of the issue
If you do not have the knowledge or ability to diagnose or correct the problem

Step 1: Identify the Problem

Initial mare examinations

Use safety precautions
Use of stocks
- If the sides can open
- If they dont and mare goes down very hard to get back out
Free standing in stall
Restraint
Determination if fetus is dead or alive may be critical to subsequent decisions
Often this is not an easy task

Decision Making

Status of foal
Duration/severity of dystocia
Economic value of mare and foal
Clinician expertise
Client preference
Facilities

Step 2: Correct the Problem

Many dystocias are mild
More severe dystocias may require significant experience, specialized equipment or facilities and additional assistance
- Example: Front leg retained or flexed at the shoulder

Delivery Options:

Vaginal delivery
Cesarean section surgery
Fetotomy

Obstetrical Procedures

General Principles:

Pump lubricant into uterus
Repel fetus into the abdomen
Correct placement of body part that is out of position
Assist with delivery

Assisted vaginal delivery:

Place OB chains or nylon straps
Apply tension on chains
- Work with mare
  - Pull when she is pushing
  - Relax when she stops pushing

Outcomes of Dystocia

Foal survival rate:
- Early decision made and equipment and facilities available
Mare survival rate:
- Relatively high
Mare future reproduction:
- Depends on the dystocia that mare had

Medical Risks of Dystocia

Mare

Retained placenta
Peritonitis
- Inflammation of the abdominal wall/lining
Laminitis
- Inflammation of the feet
Trauma
- Retinal region
- Uterine tear
- Cervical tear
- Prolapses
  - Not very common

Foal

Oxygen deprivation
Failure of passive transfer
Trauma
- Rib fracture
- Ruptured bladder
  - Can be corrected surgically

‘On Farm’ Obstetrics: Elbow Lock

Orientation

Frontwards presentation
Right side up
Both front feet and muzzle visible
One leg protrudes more

Problem

Elbow ‘caught’ on pelvis

Elbow Lock

‘On Farm’ Obstetrics
- Pull between contractions
- Foal usually delivered unassisted with subsequent contractions
- Provide assistance only if needed

‘On Farm’ Obstetrics: Red Bag

Orientation

Brick red, velvety membrane protrudes through vulva

Problem

Failure to rupture outer placental membrane
Premature placental separation
Foal at high risk of hypoxemia

Emergency situation

Call for farm assistance
- Rupture membrane immediately which will “break her water” (allantoic fluid exits)
Assist with delivery
- Use guidelines to assist

Other

Retained fetal membranes
Cesarean section
Hemorrhage from uterine or ovarian artery
Uterine prolapse
Uterine laceration

Keys to Successful Foaling Season

Owner/foaling attendant education
Communication
- Owner
- Breeding farm staff
- Veterinary staff
Preparation
- Foaling kit
Emergency plan

Foal Care

Neonatal Care

Normal behavior:
- Gets sternum within 5-10 minutes
- 1-2-3 rule: 1 hour be standing, 2 hours want them to nurse, 3 hours pass meconium
  - Can give enema of sterile saline if foal is straining to pass meconium

Importance of Colostroum

Passive transfer of immunity
Risk in immunoglobins
Good Quality
- Score: 21 or greater the foal should get enough antibodies, 20 or below not enough antibodies
  - Bricks %
Produce 2.5-5 L of colostrum
- Some mares are poor quality colostrum producers or will drip colostrum when they are starting to get close
- Maiden mares will produce less quality colostrum

Immunoglobulin Classes in the Foal → IgG MOST IMPORTANT

Passive Transfer of Immunity

Foals have enterocytes: cells that line the small intestine
- Have the ability for Nonselective pinocytosis is how macro molecules are absorbed
Immunoglobulin Absorption
Rapidly declines after birth
“Gut Closure” → switching from immature cells to mature cells; 24 hours after birth
Blood draw
Plasma greater than 800 mg/dl → Snap test
- Partial failure of passive transfer: if it is between 400-800 mg/dl
- Failure of passive transfer: less than 400 mg/dl
  - Check blood about 12 hours
Risk of pneumonia, septicemia, and septic arthritis
Treating FPT
- < 12 hours: Oral colostrum/IgG
- > 12 hours: IV hyperimmune plasma

Care of the Neonatal Foal

Temperature
- Normal 99 - 102
Umbilicus
- Dip in diluted chlorhexidine
- Colts can urinate out of their umbilical stubs
- Check temperatures

Nutrition

Nursing
- 110 lb foal drinks ~ 15 L of milk per day
- 8 times an hour
Size at birth
- About 10% of mature body weight when born
- 60% of the height that they are going to be
Rapid growth
- 2-3 lbs per day in weight
- 0.3-0.4 cm per day in height
- Smooth steady grow curve
- 8,000 calories per day
Forage
- 2-3 weeks of age they will get fiber digesters
- Alfalfa mix → foals growing bones and mares lactation
  - 2-3 months supplemental feed
    - Balance → no oats and grass forage hay
    - High quality protein → 2:1 calcium phosphorus
    - Proper mineral balance
  - Increase concentrate with age
  - Don’t offer free choice concentrate

Microbial Fermentation

Important functions
- 1. Break down compounds to make nutrients available
- 2. Protecting the GI tract from pathogens

Neonatal GI Tract

Foal born with few or no microbes in their gut
Rapidly colonize after birth

Feeding the foal and the microbes!

Coprophagy

Foal eating mares poop
- Probiotic from moms poop and for the mare to get more fiber

Orphan Foals

Milk replacer
- Mares milk is higher in lactose 6-7%
- Milk fat is lower in mare milk where ruminante % is higher
  - All encompassing milk replacer isn't really made for foals
Train to bucket
- Bottle fed can happen but would have to feed every 2 hours
Pelleted concentrate
- 1-2 months only can start weaning off of milk replacer
Social aspects
Nurse mare option

Care of the neonatal foal

Feal consistency
- Watch fecal consistency, while normal varies we don’t want diarrhea
- Feces shows microbial/digestive health
  - 3-4 days poop 1-2 a day
Biosecurity
- Handle mares and foals first before other horses stalls
- Keep separate equipment

Parasites

Main concern: Roundworms/Ascarids (Live in the intestines and can cause a blockage)
- Highly resistant to ivermectin and moxidectin
- Benzimidazoles effective
  - Safe Guard
  - Panacur
  - Anthelcide + EQ
- Administer by weight

Parasite Control

Treat with anthelmintics 4 times in the first year

2-3 months to target Ascarids
Before weaning (4-6 months)
1. Fecal egg if still have ascarids
9 months (can do fecal egg count)
12 months
1. Treat with the rest of the heard
2. 2x a year spring and fall
3. Fecal egg count in fall
  1. Ivermectin, no combo requited

Vaccinations

Colostral antibodies lasts about 4 weeks

Core vaccines ( minus rabies)
- 1st dose: 4-6 months
- 2nd dose: 4-5 weeks after 1st
- 3rd dose: 10-12 months
Rabies
- 1st dose: 6 months
- 2nd dose: 4-6 weeks after 1st
Coggins
- Not done until about 6 months old
- Equine infections anemia is what is looking for in a coggins test

Foal Diseases and Disorders

What to expect from the normal foal

Nursing and Sleeping
Close to mom
Poorly coordinated

Normal Vital Signs

When things go wrong

Maturity
Meconium impaction
Diarrhea
Neonatal maladjustment syndrome
Neonatal isoerythrolysis
Developmental orthopedic disease

Mucous Membranes

Salmon pink
CRT < 2 sec

Maturity

Premature
- Less than 320
- Placentitis → infection in the placenta → leading causes
- Major issues in their joints, they aren't developed
Signs of Premature
- Muscle weakness (delayed nursing)
- Weak suckle
- Poor thermoregulation
- Poor glucose regulation
- GI and renal immaturity
- Entropion
Dysmature
- Normal gestation however they have similar signs/behaviors to a premature foal
  - Can get entropion

Meconium Impaction

Signs
- Straining to defecate
- Swishing tail
- Depressed
- Dorsal recumbency
- Abdominal distention and colic
Treatments
- First step is to give an enemia
  - Can give right when foal is born
  - Don’t give more than 2 within the first 24 hours
- Banamine if it is serious

Diarrhea

2 Main categories
- Infectious
  - Caused by a particular pathogen
    - Bacterial Causes
      - Clostrudium difficile, Clostridium perfringens, and Salmonella
      - Opportunistic pathogens
      - Severe diarrhea, fever, sepsis
      - Produce toxins, inflammation in GI tract, and increase intestinal permeability
    - Treatment/Protection from Infectious Diarrhea
      - IV fluids
      - Antibiotice
      - Probiotics
      - Gastroprotectants
      - Prevention
      - Good hygiene
- Non Infectious
  - Foal heat diarrhea – not caused by the first heat in the mare
    - Transient, Self resolving (1-3 days)
    - Associated with changes in microbial community
      - Up to 80% of foals will develop transient diarrhea
  - Treatment
    - Supportive
    - Monitoring hydration status
    - Monitor for signs of systemic disease
  - Necrotizing Enterocolitis
    - Related to prematurity?
    - High death rate
    - Signs: Fever, depression, severe colic, diarrhea
  - Nutritional Causes
    - Orphaned or hospitalized foals
      - Feed correct milk replacer
    - Lactose intolerance
      - Rare dont see it all too often
    - High milk producing mares
      - Foals tend to have more diarrhea

Neonatal Maladjustment Syndrome

Hypoxic ischemic encephalopathy, perinatal asphyxia, or “dummy foal”
- Potential Causes
  - Placentitis
  - Prematurity
  - Post maturity
  - “Red bag”
  - Dystocia
- Wonder around stall, weak suckle, decline in behavior
Treatment
- “Dummy jug” IV cocktail
- IV fluids
- Broad spectrum antibiotics
- Intranasal oxygen
- Madigan squeeze

Neonatal isoerythrolysis

Foal inherits blood type different from mare
- Signs 6-72 hours after birth
  - Dull and lethargic
  - Pale yellow mucous membranes
  - Tachycardia
  - Dark yellow urine
  - Fever
Prevention and Treatment
- Blood type
- Muzzle
- Treat fever and prevent infection

Developmental Orthopedic Disease (DOD)

Growth disturbances and orthopedic problems
Osteochondritis dissecans (OCD) → bone chips in the joints
Physitis
- Flexural deformities
- Angular limb deformities
- Bone chips
Treatment
- Restricted exercise
- Corrective trimming
- Splints, casts, wrapping
- Medication
- Surgical
Preventing DOD
- Proper feed formulation
- Minerals
  - Cu and Zn
  - Mn and Mg
  - Ca and P
- Overfeeding

Lactation

Lactation

Lactation is the process of secreting milk from the mammary gland
Mammals are the only class of organisms that produce milk

Importance of Milk

Provides nourishment for young
Provides protection for neonates against disease
Provides human food
1. What are the major components of milk?

Milk Composition

Macro nutrients
- Protein – 1-2$
- Fat – 2%
- Carbs – 6-7%
Micro Nutrients
- Vitamins
- Minerals
Water
Protein
Carbs
Vitamins
Minerals
Fat

Over 50 different types of oligosaccharides

Mares have 4 quarters but only 2 teats

Alveolus

Functional unit
- Where the milk is produced
- Milk secreting unit of the mammary gland
- Lined in alveoli

Myoepithelial Cells

Muscle cells that surround the alveoli
- They have a hormone receptor for oxytocin (peptide hormone)

Pregnancy Loss

Pregnancy loss timeline

Day 0 - 14: Pre maternal Recognition
Day 15 - 40: Early embryonic loss
Day 28 - 120: Endometrial cups
Day 40+: Fetal stage
Day 150: Placental dependence

Terminology

Conceptus: all of the products of conception
- Fetus, placenta, fluids, etc
Embryo: portion that will eventually turn into the foal
Fetus: the offspring is still in utero and can be defined or easily identified as that species
- Generally, < 40 day = embryo
- > 40 days fetus
- Foaling rate = live foal rate = fertility rate

Pregnancy loss: Early Embryonic Loss

Average foaling rate: 60 - 70%
- 35-40% of mares will lose that pregnancy at some point
10 to 15% of all pregnancies end in early embryonic loss
- Sub fertile, older mares → 7-8 times more likely to lose a pregnancy
  - After day 75 the frequency of pregnancy loss starts to lower
- Causes
  - Maternal
  - External
  - Embryonic

Early Embryonic Loss

Endometrial cups
- eCG production
- Prevents return to estrus
Twin pregnancies → leading causes of pregnancy loss
- Twin fixation – competition – loss
- Management

Causes of early embryonic death

Maternal factors:

Low progesterone

Failure of maternal recognition
Primary CL deficiency
Endomaturitis → inflammation of the uterus

Oviduct Environment

Reduced oviduct secretions
Embryonic toxins
Incorrect timing
Scar tissue

Uterine Environment

Endometritis
Fluid in uterus during early pregnancy
Endometrial cysts
Lack of required secretions
Chronic endometrial disease

Age of Mare:

Light levels of FSH and LH
- Quality of oocyte decreases
Cellular division is slower

External factors

Stress
- Decreases progesterone production
Inadequate nutrition
Ingestion of toxins or infectious agents
- MRLS in KY (2001) → caused by tent caterpillars
  - Mare reproductive loss syndrome

Embryonic Factors

Small size and defects
Chromosomal abnormalities

Diagnosis of embryonic death

Small for age vesicles
No embryo development in vesicles and/or no heart heat at day 24
Development next to endometrial cyst
Uterine edema
- Treatment
  - Provention
  - Progesterone
    - Continue until day 75 or 100
      - Can still even fail

Pregnancy Loss: Late Term

Abortion vs stillbirth
- Abortion: pregnancy ended at any point however usually used in the beginning of pregnancy
- Stillbirth: foal should still be viable but for some reason that foal is not
  - Twisted umbilical
10% of pregnancy
- 6 to 11 month: placental dysfunction
- Acute: EHV - 1 or a twisted umbilical cord
- Chronic: do have signs, discharge, thickening of the vulva
  - Usually bacterial or fungal causes

Late term abortions

Viral: Equine Herpevirus 1
Bacterial
- Streptococcus zooepidemicus
- Leptosprosis
Fungal: Aspergillus spp.
Always treat as infections
- Submit fetus and placenta for analysis
- Biosecurity
- Sample types

Uterine Endometrium

Interior of uterus
Functions:
- Secretions that support the developing placenta and embryo when it comes it
- Clear any bacteria and debris after that breeding
Anestrus - atrophied
- Not active during the winter months
Estrous - edema present but not a lot of fluid

Uterine Health and Pregnancy

Uterine environment must be infection free to support conceptus and placenta
Endometritis:
- Major cause of infertility or sub fertility mares
- Hard to diagnose
- Most cases are non infectious

Uterine Clearance in normal mares

Oxytocin released during breeding
2 - 4 hour post breeding: healthy sperm arrive at oviduct
Inflammation in the uterus
1. Release of immune cells: Neutrophils, Antibodies, Complements, Polymorphonuclear cells (PMN)
2. PGF2a is produced
> 4 hour sperm collected from uterus phagocytized
Lymphatic system in uterus drain fluid
Inflammatory response lasts 40 to 72 hours post breeding

Classifications of Endometritis

Sexually transmitted disease
- CEM - contagious equine metritis (bacteria)
- All TB mares bred to imported stallion need to be tested
- All European mares tested prior to breeding
Persistent mating induced endometritis → Leading Cause
- Contamination in the breeding process
- The cleaning process doesn't happen
- Inflammation is sustained
Chronic endometritis
- Chronic degenerative endometriosis
- Due to anatomical issues in the mare

Persistent Mating - Induced Endometritis

15% of mares →

Normal cycle, lose early conceptus or fail to get pregnant
Incomplete voidance of uterine fluid and seminal products
- Poor uterine contractions
- Anatomical defects
- Cervical malfunction
- Inadequate lymphatic drainage
Reduced uterine clearance = decreased pregnancy rate

Diagnosis

Ultrasound the uterus
Cultural swabs → swab, plate/culture swab
- Should have a clean uterine culture prior to breeding
Uterine biopsy → take a clip of tissue from uterine lining, only looking at that specific location not looking at the whole uterus
Uterine lavage → sterile procedure, through vaginal, flush the uterus, collect fluid that was flushed and culture fluid

Treating persistent mating induced endometritis

Goal: Remove all fluid
AI preferred over live cover
Fresh/Cooled preferred over frozen

Oxytonic: 4 - 6 hours until cleared
Uterine lavage
1. 10% povidone - iodine
2. Oxytocin
3. Check at 24 hours

Chronic Endometritis

Causes:

Infections agent
Contaminantes from fecal
General microflora that have gotten out of hand
Poor perineal anatomy

Long term inflammatory responses cause degenerative changes

Glandular function
Early conceptus support
The longer the infection the greater the damage

Diagnosing Chronic Endometritis

Positive culture from fluid and biopsy
Ultrasound
External signs
- Discharge from vulva, matting of tail hairs
- Returning to estrus day ahead of schedule
- Vaginal speculum exam – reddening of vagina, discharge through cervix, pooling urine, manure in vagina

Treatment for Endometritis

Fix physical defects
Uterine flushing
Oxytocin and Antibiotic: can give a IM or local antibiotic depending on the kind of infection
Mucolytic irrigations
- Excessive secretions of mucus interferes with antibiotic effectiveness
- Some bacteria or fungi produce biofilms

Diseases of the Placenta

Causes of placental dysfunction

Placentitis
Alteration of blood flow
Inadequate placental attachment
Edema of placenta
Maternal disease or malnutrition

Results

May deliver live and viable foal at 310 days
Malformed fetus, fetal death, mummification, abortion, fetal growth retardation, prematurity, still birth, and neonatal weak foal or foal death
Low birth weight
Weak and septic foals

Placentitis and Abortion

Ascending Placentitis
- Degeneration and necrosis of microvilli
- Thick and endematous
- Changes from bright red to pale
- Vaginal discharge
Nocardioform Placentitis → Increase in 2020
- Sticky mucous brown plaque on horns
- No discharge
- Lots of unknowns
  - Hot, dry fall could be a leading cause

Clinical Signs

Vaginal discharge
Premature lactation
Transabdominal ultrasound
- Premature separation of placenta
- Monitor fetus for normal heart rate, fluids, activity and size
Measure maternal blood progesterone, estrogens – normal levels?

Treatment

Goal:
- Control the infection
- Decrease inflammation in the uterus
- Increase blood flow to the uterus
- Decrease any uterine contractions
Use an antibiotic → SMZ most common
Banamine
- NSAID
- Helps with pain
Regumate
- Helps support progesterone
Estrogen or isoxsuprine
- Helps with blood flow to the uterus
- Helps with attachment of the rest of the functioning placenta

Outcomes for the foal

Mid pregnancy: most likely will loose pregnancy, can try to safe pregnancy but very unlikely
Late pregnancy: Can treat if catches it early
- If foal lives to term: 310 days or greater
  - Premature rise in ACTH and cortisol levels that are associated with final maturation
  - May be weak or septic
  - Dummy foal

Stallion A & P

Basic Components

Function: Is to produce and deliver sperm into the females reproductive tract

External genitalia
- Penis
- Prepuce
- Scrotum
- Muscles
- Testes and epididymides

Pelvic Tract

Vas deferens
Spermatic cord
Accessory sex glands
- Ampulla
- Seminal vesicles
- Prostate gland
- Cowpers gland/bulbourethral gland

Scrotum

Purpose: Contain, protect, and thermoregulate the testes epididymis, spermatic cords, and cremaster muscles

Connective tissue and smooth muscle fibers

Layers of the scrotal wall

Skin
Tunica dartos
Parietal vaginal tunic
Visceral vaginal tunica
- Tunica albuginea
- Testicular parenchyma

Testes

Function: produce sperm and produce hormones

Fetus: testicles are up in the abdomen

Prior to birth
- Testicular descent – last 30 days of gestation and first 10 days postpartum
- Located within the inguinal ring

Testes: Seminiferous Tubules

Site of spermatogenesis
Developing sperm and precursors
- Take about 2 months to develop sperm
Sertoli cells
- Within the tubules where the sperm cells are developing
- Help support spermatogenesis
- Produce estrogen
Leydig cells
- Produce testosterone

Epididymis

3 parts: Head, Body, and Tail

Responsible for:
- Transport
- Concentration
- Storage
- Maturation

Morphology of the Stallion Spermatozoa

5 main regions

Head: condense nucleus, covered by the acrosome
Neck
Midpiece: had a helix mitochondrial (ATP)
Principal piece: longest part of the tail
End piece: very end of the tail

Spermatic Cord

Cremaster muscle
Pampiniform plexus
- Arterial blood comes in and vein blood comes out
Vas deferens

Accessory Sex Glands

Seminal vesicle, ampulla, prostate gland, and bulbourethral glands
Purpose:
- 60 - 90% of the total seminal fluid volume
- Support sperm

Ampulla

Enlarged glandular portion of the vas deferens
High concentration of potassium and protein
Stores some semen

Seminal Vesicles

Produce large portion of seminal plasma
Secretions: energy for sperm
Dilate and elongate when stimulated

Prostate Gland

Secretion: Thin, milky, alkaline
Neutralize acidity of the epididymal secretions

Bulbourethral Glands

Secretions: Alkaline, mucus - like
Neutralize acidity, lubrication

Urethra

The urethra serves as the joint excretory canal for urine and semen

Prepuce or Sheath

Protects non erect penis
Internal preputial fold
External preputial fold

Erection

Large percentage of tissue in the penis for erection
- Corpus cavernosum
- Corpus spongiosum: just surrounds the urethra
- Hemodynamic: it reacts to an increase in blood pressure

Ejaculation

The expulsion of semen from the penis
Stimulated by nerves
Muscles surrounding accessory glands contract pulsations with about 75% of total sperm in first 3-4 pulses

Puberty

Defined as the capability to reproduce

Infantile stage: < 6 months
- Does not produce functional leydig cells and indifferent supporting cells
Prepubertal stage: Can change from breed and season how long this may last
Puberty stage: Stallions reach sexual maturity at 2 - 4 years of age

Cryptoorchidism

Failure of the testes to descend into a normal scrotal position
- Heritable
Three ways to check
- Rectal palpation
- Hormonal challenge
- Ultrasound

Penis

Musculocavernous type

3 parts
- Root
- Shaft
- Glans penis
Preputial ring
Non erect: 50 cm long by 2.5 to 5.0 cm in diameter
Erection increases the length and diameter of the penis about 50%
- Glands penis increases 300 - 400% in diameter through engorgement

Puberty

Definition: When a colt produces viable spermatozoa in the ejaculate and is capable of fertilizing and oocyte

Typical age: 12 - 18 months
- First sperm 12 - 14 months
Hormonal change – day light changes
- Testosterone: develop sex characteristics, libido, spermatogenesis
Physical development

Sexual Maturity vs Puberty

Puberty does not mean full reproductive maturity

Puberty: First viable sperm present
Sexual maturity: max sperm production and breeding capacity
Behavior vs fertility
- Libido will develop before sperm actually develops
Management implications
- Separate pastures by sex
- Geldings for a baby sitter for colts

Factors Affecting Age of Puberty

Breed: pony breed early, draft breeds late
Nutrition
Season
Growth rate

Cryptorchidism: Failure of one or both testes to descend into the scrotum

Types: Unilateral and bilateral

Locations
- Abdomen
- Inguinal canal
- Subcutaneous inguinal region
Fertility implications
- The testis that is not descended will not produce viable sperm
- Unilateral will still be fertile
- Bilateral is sterile
Management
Heritable trait

Assisted Repro Techniques

Assisted Reproductive Techniques

Useful for

Mares
- That have issues with her uterus
- Decreasing risk of injury
- Still showing
Stallions
- Decreasing injury
- Quality of semen

Pregnancy Rates

Average: 50 - 60% conception rate on first cycle
Average conception rate for season: 60 - 70%

Techniques

Artificial insemination
Embryo transfer
In vitro fertilization
Oocyte aspiration
Intracytoplasmic sperm injection (ICSI)
Nuclear transfer (cloning)

Artificial Insemination

Fresh/cooled semen: 60-90% pregnancy rate

Frozen semen: 35-40% (range 0 - 70%)
- Factors
  - Timing
  - Freezability
  - Mare age/uterine health

Pro: Taking out interaction between mare and stallion

Cons: Increases human injury (stallion side)

Embryo Transfer

Process: Breed mare, collect embryo, transfer to recipient mare

Day 0: Ovulation
Day 7 - 8: Flush
Transfer
- Mares don’t superovulate very well
  - Hormones: Use porcine FSH or use equine specific FSH
  - Anatomy: They only ovulate in a single horn

Recipient Mare Selection

Enhanced or restricted fetal and postnatal environment effects glucose.insulin metabolism

Uterine environment affects foal metabolism outcomes

Embryo Transfer

Recipient mare selection
- Temperament
- Repro conformation
- Age (late teens no older mares)

Recipient Mare Management

Normal cycling by February

Monitor follicular development
- Receive embryo 4 - 8 days post ovulation

Donor Mare Management

Goal: Recover clean embryo, of size that transfers well

Uterine status is important!
Daily ultrasounds
- Follicular development/ovulation
- Condition of the uterus
SIze of embryo: 7 - 8 day post ovulation
- Too big: start to get too sensitive/fragile
- Too small: wont be able to find it in the fluid

Uterine Flush for Embryo Transfer

Sterile procedure
- Do give the mare some oxytocin to help relax the cervix
- Will sedate the mare
Immediately transferred, maintained in media, or frozen
Evaluate for quality

Transfer of Embryo to Recipient Mare

Good uterine tone and closed cervix
Sedate mare, clean perineum, vulva, vestibule
Load embryo into transfer gun or pippette

Managing Mares Post Transfer

Risk of bacterial contamination – endometritis
Recipient mare protocol
- Time of transfer: banamine, antibiotics
- Pregnancy check: days 11, 13, 17, 23, and 29
Donor mare management
- Biggest risk: becoming pregnant
  - Administer PGF2a after flush
  - Fluid not completely removed
    - Check day after flush
  - Monitor signs of estrus

Embryo Transfer

Oocyte Aspiration

Collect oocytes directly from ovarian follicles

Transvaginal aspiration (TVA)
Ovum pick - up (OPU)

Collecting immature oocytes – require in vitro maturation

Mature – lower recovery rate, ready for ICSI

Sedate mare
Ultrasound probe placed transvaginally
Ovary stabilized per rectum
Needle guided through vaginal wall to follicle
Follicular fluid aspirated
Oocyte recovered from fluid in the lab

Oocyte Aspiration and Transfer

Collection of follicles from donor and recipient mares

Collect oocyte (donor)
Remove recipient oocyte
Transfer to oviduct
Breed recipient

Oocyte Transfer

Oocyte transferred to recipient
- Trans - abdomina l
- Remove recipient mare oocyte
- Deposit oocyte in oviduct
AI recipient mare
Highest success rate of the ARTs

Intracytoplasmic Sperm Injection (ICSI)

What is ICSI?

One sperm cell injected into oocyte
Done in vitro
Requires micromanipulator

Why use ICSI?

Poor semen quality
Limited semen
Preserving genetics
Multiple oocytes

Options for embryo

Immediate transfer to oviduct of recipient mare
Culture 24 - 48 hours then transfer to oviduct
Culture 7 - 8 days then transfer to uterus
- Success rate: Varies between 20 - 50 %

Gamete Intrafollopian Transfer (GIFT)

Performed via standing laparotomy → done more surgically for the recipient mares

Advantage:
- Lower quality or lower number of sperm → puts right in the oviduct
- Lower risk of post breeding endometritis

In Vitro Fertilization (IVF)

Standard method of fertilization of isolated oocytes in most species

More successful with frozen than fresh semen

Nuclear Transfer (Cloning)

First equids cloned (2003): a mule in Idaho Gem, and a Haflinger; Prometea

Why clone?
- Genetics → gelded colt
- Preserving endangered breeds
- Making a genetic copy of the offspring
Success Rate? → very low but possible
- More frequently done in polo ponies
- 800 oocytes – 22 embryos – 17 transferred – 4 pregnancies – one full term foal

Oocyte from mare and denucleated
Tissue from horse to be cloned is collected and cultured
Chromosome from donor cell transferred to cytoplasm of oocyte
Embryo transferred oviduct of recipient or cultured in vitro then transferred to uterus of recipient mare

Health of cloned foals

Increased risk of maladjustment syndrome, enlarged umbilicus, contracted tendons, angular deformity of front limbs
- After 2 weeks, appear normal
  - > 200 polo ponies produced via cloning in Argentina since 2009

Genetic Testing

Basic Genetics

4 nucleo tides
Strands of DNA have different segments that will code for building different structures in the body
Genes have different alleles that cause a different phenotype

Genome

“Instructions” for making an organism
Horses have 64 chromosomes in 32 pairs
- Shvulski horses have 66 chromosomes

Genotype

Phenotype

Epigenetics

Influence gene activity
Change how the gene is expressed

Equine genome

Published in 2007

“Blueprint” or starting point of that horses make up
Compare between animals
Identify traits

Importance of genetic testing

Traits
DNA and parentage verification
Genetic diseases
Color and patterns
- Palamino
- Buckskin
- Appys
Making wise breeding decisions!

The “Speed Gene”

Early findings: Nucleotide at one part of the myostatin gene associated with speed

C nucleotide: speed
T nucleotide: stamina

Myostain gene and race length (hormone depending on muscle growth)

C/C: Sprint performance (less than 1 mile)
C/T: middle distance (~1 - 1.5 miles)
T/T: longer distance (> 1.25 miles)

Important to note that speed is controlled by more than just that one gene

DNA and parentage verification

Hair, blood, tissue
DNA testing
Parentage verification
- Sire and dam must be DNA tested

Breed requirements

AQHA: embryo transfer, shipped semen, racing, descendant of impressive
Jockey Club
APHA

Genetic Diseases

6 panel plus genetic testing → Primarily found in stock horses

HYPP: hyperkalemic periodic paralysis
PSSM1: polysaccharide storage myopathy type 1
MH: malignant hyperthermia
GBED: glycogen branching enzyme deficiency
HERDA: hereditary equine regional dermal asthenia
MYHM: Myosin heavy chain myopathy

Others

WFFS: Warmblood fragile foal syndrome
OLWS: Overo letha white syndrome
Arabian panel” Cerebellar abiotrophy, lavender foal syndrome, SCID

Terminology

Dominant and Recessive Alleles

Example: E = dominant black coat color, e is recessive red gene
EE or Ee = black base coat
ee = red based coat
- Homozygous: two identical alleles
- Heterozygous: two different alleles

Hyperkalemic Periodic Paralysis

Dominant disease

Causes muscle spasms
Interrupts flow of sodium in/out of muscle
Diet management is key!
- Low potassium diet
- Regular exercise/turnout

Polysaccharide Storage Myopathy Type 1 (PSSM Type 1)

Dominant condition

Abnormal synthesis of glycogen in the muscle
Muscle pain and cramping
- Breakdown of muscle fiber
Management
- Low starch/sugar diet
  - Cannot break down the glycogen

There is a type 2 but there is not genetic testing for it but they do experience similar symptoms

Hereditary Equine Regional Dermal Asthenia (HERDA)

Recessive Condition → need both copies to be expressed

Degenerative skin disease
- Stretchy, elastic, sloughing skin
- Severe skin wounds
AQHA, appaloosas, paints
No treatment or cure
- Wont know they have herda until they start under saddle
Seen more in the cutting horses

Glycogen Branching Enzyme Deficiency

Recessive disease

Usually see in the foal but the foal more than likely doesn't make it
Signs: have no energy, very weak, cannot stand
- They cannot make glycogen
No treatment or cure
- These effected foals that are alive and are not still born or aborted are normally euthanized
AQHA and Paints
Glycogen synthesis disorder

Malignant Hyperthermia → RARE

Dominant disease

AQHA and Paints
Mutation results in excessive Ca release in muscle cells
- Increase metabolic rate
- Can result in death
- Triggered by stress and anesthesia
Treatment: can give a drug when they are under anesthesia
Cant test for it, not a death sentence if know that they have it

Myosin Heavy Chain Myopathy

Dominant Disease

AQHA and other stock breeds
See muscle stiffness, muscle drops rapidly

Two disease presentations

Immune mediated myositis
Non exertional rhabdomyolysis

Treatment/Management

No strangles vaccine
Use intranasal vaccines when possible
Space out vaccinations

Coat color genetics

Over 300 genes control pigmentation

Base coat colors: CHestnut and Black
- Agouti:
  - A: restrict the black at the points
  - a: distribute the black all across the body
- Red factor: 3 alleles → E, e, e^a
  - Sorrel if they are homozygous with E and a lowercase a
Shade
- How light or dark the horse is
Dilution genes
- 6 dilution genes
- Reduce the amount of pigment expressed
  - Champagne
  - Cream
  - Dun
  - Mushroom
  - Silver
  - Pearl
White spotting pattern genes (PATN1)
- Gray, roan
  - Progressively loose pigment
  - At risk for developing melanoma
- Tobiano, overo, sabino
  - Can get the lethal white syndrome if not careful when breeding these
- Appaloosa spotting (leopard complex) or pattern