Equine Repro Flashcards
Dourine
** REPORTABLE**
- chronic , venereal disease caused by Trypanosoma equiperdum
- CS - genital edema, mucous discharge ( with trypanosomes)–> silver dollar sized skin plaques–> progressive paralysis
- 50-75% mortality
Contagious equine metritis (CEM)
REPORTABLE
- EQUINE VAGINAL DISCHARGE
- typically not in North America, but there have been a few infections
CS- ** infertility, endometritis with profuse mucopurulent vulvar discharge in a mare recently imported from Europe or Japan**
agent = taylorella equigenitalis
Most common infectious cause of equine infertility in North America
Streptococcus zooepidemicus
Equine coital exanthema
- acute , mild disease from which most horses recover on their own
- agent = equine herpes ( EHV-3)
CS- papules, ulcers, and depigmented scars on vulva, perineum, penis, prepuce
- does NOT affect fertility
** isolate affected horses until lesions have healed ** , sexual rest, or only AI
No vaccine available
EHV - 1 clinical presentation
- foal born premature, weak, and in respiratory distress –> dies within hours
- aborted late term fetuses (multiple) within the herd
- necropsy ( dead foal ) = interstitial pneumonia and necrosis/ atrophy of the thymus
seasonality / cycle
seasonally polyestrous and cycle when the length of daylight is long
anestrus
- occurs during winter when the daylight is short
- ovaries are inactive , with no significant follicles or corpora lutea.
- do not ovulate
- plasma levels of estrogen and progesterone are low
- uterus is flaccid, cervix is short/thin/open or readily opened
- (seasonal anestrus) - tend to be passive in the presence of stallion
estrus
- sexually receptive to stallion
-increased tone of cervix and uterus
-
ovulation
stimulated by surge of LH at end of transition
–> after ovulation, interovulatory estrous cycle is established
** occurs 0-2 days before end of estrus
estrous cycle length
21 days ( mare ovulates regularly every 21 days )
estrus length
2-8 days ( varies )
how many follicular waves do mares have
- 2 follicular waves each cycle
- first wave = during diestrus –> follicles degenerate
- second wave = occurs after luteolysis and is associated with estrus
** usually one follicle becomes dominant and ovulates when its large enough.
dominant follicle progression to pregnancy or non-pregnancy ….
- DF enlarges and softens just before ovulation —> oocyte is released —> corpus luteum forms and produces progesterone —> stimulates closure of cervix and increase of uterine tone —> CL matures and becomes responsive to PG2alpha in 5 days
** if pregnant –> no luteolysis
** if NOT pregnant –> luteolysis occurs at 14 days —> mare returns to estrus —> continues to cycle
cycle manipulation by:
- supplementing 16 hours of light each day
PGF2a (IM) during diestrus
- causes luteolysis and allows follicle to mature and ovulate
- CL must be 5-14 days old to respond to PGF2a
- mare will come into estrus 2-5 days after administration (PGF2a)
sustained release of GnRH analogue ( deslorelin acetate)
- causes ovulation within 48 hours to an estrous mare with a developing dominant follicle
Mares in estrus ( behavior near stallion )
- raise tail, squat, urinate, evert vulvar lips, tolerate copulation (receptive)
Mares in diestrus ( behavior near stallion)
- squeal, kick, bite, reject advancements
cervix during diestrus
- cervix is closed and has tone with long cylindrical shape
- progesterone (increased)
cervix during estrus
- cervix is relaxed and edematous
- progesterone (low)
- estrogen (high)
cervix during anestrus
- cervix is short/thin/open or readily opened
- steroid serum concentrations = low
organisms most commonly associated with endometritis
- strep. equi subsp. zooepidemicus
- E. coli
- Pseudomonas
- klebsiella
after 150 days
ovaries not felt per rectum
midterm pregnancy dx
two uterine horns with palpable endometrial folds , ovaries can’t be IDed pelvic canal
Stage I (parturition)
- signs of abdominal discomfort and restlessness due to uterine contractions
- uterine contractions increase
- fetus rotates to dorsosacral position before expulsion
- increasing pressure in the uterus causes –> chorioallantois to protrude
- ends with the rupture of the chorioallantois at the cervical star and the release of tea-colored allantoic fluid
“ breaking her water”
Stage II (parturition)
- starts with rupture of chorioallantois and ends when the fetus is expelled
- usually lasts 15- 30 mins
- allantoic fluid lubricates canal –> facilitates expulsions of amnion and fetus
- amnion = whitish, fluid filled membrane
- fetus expelled with intact umbilical cord and covered in amnion( which ruptures by movement)
** if does not rupture, need assistance or else foal will suffocate
** foal should be delivered within 30 mins of chorioallantois rupture
Stage III ( parturition )
- expulsion of fetal membranes
- normally pass rapidly within 3 hours
- if 3 hours passed = retained fetal membranes –> administer oxytocin at 15-30 minute intervals until they pass –> until 8 hours
- after 8 hours –> further intervention needed
premature separation of the placenta
- bright red, velvety, intact chorioallantois with a central, tan, villous, star shape between the vulvar lips before the foal is delivered
presence of chorion at vulvar lips
indicates separation from endometrium before foal is able to breathe spontaneously –> chorioallantois must immediately be ruptured to prevent foal asphyxiation
at what day of gestation can you prevent abortion from twining
day 30
most common cause of viral abortion
EHV -1 ( last trimester)
- mares should be vaccinated at 5,7,9 months of gestation
ovulatory follicle diameter
30-50 mm
Egg cycle
ovulate 1 egg via ovulation fossa —> egg spends 5-6 days in oviduct —> fertilized in oviduct —> morula enters uterus at day 6 —> morula moves around for * maternal recognition of pregnancy* —> starts to implant at day 16
Signs of equine estrus are due to 2 things
- absence of progesterone
- presence of estradiol
Hormone control of estrus cycle
- give PGF2a when CL is 6-14 d old
- -> estrus in 2-5 days —> ovulate in 3-10 days
- PGF 2a can cause cramping, sweating, colic for 30 mins upon injection
- -> estrus in 2-5 days —> ovulate in 3-10 days
- Give progesterone/estradiol IM for 10d –> then give PGF2a on day 10 –> estrus in 6 days —> ovulate in 10-12 days
- Give Progesterone PO SID for 12-15 days —> estrus in 4-5 days after last dose –> ovulation = variable
Ovulation induction
- Give hCG if follicle > 35 mm –> ovulation within about 36-48 hrs
- Give GnRH if follicle > 30 mm –> ovulation within about 48 hrs
Suppress estrus
Progesterone PO SID
Ideal time to breed
in Final 48 hours before ovulation (but can still work if within 12-18 hours after)
Annual breeding soundness exam includes:
- semen evaluation
- equine viral arteritis (EVA) status
- +/- CEM (contagious equine metritis) status
Satisfactory semen if :
- 70% pregnancy rate ( 40 live covers OR 120 AIs/season )
- 1 billion morphologically normal, progressively motile sperm in the SECOND EJACULATE
Determining equine pregnancy :
via rectal
- rectal palpation > 28 days
= cervix closed, increased uterine tone, palpable vesicle - can’t feel fetus from about 100 days until late term ( because uterus drops down into abdomen)
Determining equine pregnancy :
via transrectal U/S
- see embryo at day 10
- MUST scan twice before day 30 to diagnose and rule out TWINS
- HEARTBEAT first visible at day 25
Fetal and placental assessment :
- from day 80 - term
- with trans abdominal U/S
Blood tests used to determine pregnancy ( less common and usually unnecessary )
- estrone sulfate
- estradiol 17 beta
- Equine chorionic gonadotropin ( made by endometrial cups between day 40-120) BUT can have false positive even if fetus is not viable
- episoplasty (vulvoplasty) 2 weeks before due date
Gestation length
(variable) about 340 days +/- 1 month
- Shorter in:
- young mares
- foaling in summer
- with female foals
Equine placentation
- Diffuse microcotyledonary
- epitheliochorial ( 6 layers )
- indeciduate
Endometrial cups
- around the base of the gravid horn
- secrete Equine chorionic gonadotropin
(from day 40 - 120)
Gravid horn
- larger, healthy looking , stretched out
non gravid horn
- smaller, healthy but shriveled, not stretched out
Equine pregnancy requires progesterone for maintenance : sources =
< 60 days = made by ONLY OVARIES
Day 60 - Day (150-180) = Ovaries + Placenta
> Day (150-180) = made by ONLY PLACENTA
Need supplemented exogenous Progesterone if:
- ovariectomized mare
- severe stress
- poor cervical competency
- low serum levels ( not proven to help )
Signs of parturition
variable but usually:
- Mammary development ( 3-6 weeks prior )
- Teat “waxing” ( 6-48 hrs prior )
= dried colostrum at orifice - High Calcium + High Magnesium in milk
- Sacrosciatic ligaments (tailhead) and vulva relax
Mares usually foal at night or day
Night , without an audience
Normal fetal presentation
- anterior longitudinal presentation
- dorsosacral position
- extended head and FL posture
Lengths of Stages ( Parturition )
Stage 1 = 1-4 hours
(restless mare, sweaty, anorectic, can look like colic)
Stage 2 = within 30 minutes
( Explosive, foal delivered in amnion )
Stage 3 = within 3 hours
( Placenta retained after 3 hours , RFM = emergency * unlike cattle who will pass it within the next week or so *)
Treatment of retained fetal membranes
After 3-8 hours :
- Oxytocin (10-20IU) q 15-30 mins + uterine lavage
- infuse allantochorionic space with 10-12 L of dilute betadine ( stimulates uterine contraction ) aka the Barnes method
After 8 hours ( more aggressive ):
- anti-inflammatories
- broad-spectrum systemic antimicrobials
- laminitis prophylaxis (cryotherapy, deep bedding)
- continue oxytocin and uterine lavage
Induction of parturition (RARE)
- ONLY if really necessary :
terminating pregnancy
very long gestation (13-14 months)
Mares with hydrops
abdominal prepubic hernias / tendon ruptures
(* in general, situations where its a must to remove the foal*) - only if > 330 days pregnant and developed mammary glands
Uterine involution post partum
RAPID - 6-10 days
First heat (“foal heat”) post partum
7 - 9 days post partum
Non-infectious causes of abortion
- twinning ** Most Common cause of abortion in general
- stress/ colic ( any time )
Twinning ( abortion )
Most Common cause of abortion in general
- Timing : Early embryonic death @ < 2 weeks
- Dx : ultrasound
- Prevention: 2 transrectal ultrasounds before day 30
** can terminate one of the fetuses to increases chances of other fetus’s viability ONLY if detected within 30 days **
Stress/ colic ( abortion )
- Timing: any time
- ** fetal loss due to placental insufficiency
- Dx : ultrasound
- Prevention: Progesterone
Bacterial causes of abortion
** Streptococcus zooepidemicus ** MC bacterial cause
Leptospira interrogans
Contagious equine metritis - (REPORTABLE)
Streptococcus zooepidemicus
** MC bacterial cause of abortion **
- Timing: Any time
- CS - ascending bacterial placentitis
- Dx: Culture of fetus
Leptospira interrogans
- Timing: Any time
- CS - diffuse bacterial placentitis with autolytic fetus
- Dx: Culture of fetal kidney or body fluids
CEM
** REPORTABLE **
- Timing: Early embryonic death
- CS - ** infertility, endometritis with profuse mucopurulent vulvar discharge in a mare recently imported from Europe or Japan**
- Dx: special culture medium
Viral causes of abortion
EHV-1 ** MC infectious cause of abortion
(VERY CONTAGIOUS)
Equine viral arteritis (outbreaks)
Equine infectious anemia (rare)
Equine herpes virus -1 (EHV-1)
** most common infectious cause of abortion **
- very contagious
- Timing: Late term
- CS - FRESH fetus within its membranes , usually NO/ FEW premonitory signs
- Dx: Viral inclusion bodies in fetal tissue
- Prevention: Vx at 3,5,7,9 months of gestation
Equine viral arteritis
outbreaks
- Timing: within 2 weeks , AFTER mare is sick with respiratory signs and vasculitis
- CS - Mare is sick, fetus is autolyzed
- Dx: Flourescent antibody (FA) in fetal tissue or mare serology
- Prevention: Vx mare BEFORE BREEDING if at risk
Equine infectious anemia (EIA)
rare
- Dx: viral inclusions ( fetal tissue or mare serology )
- Prevention: performing Coggins ( annually)
Equine dystocia = uncommon (<1%)
= EMERGENCY
Causes:
Maternal ( uncommon ) :
- twinning
- small size/ narrow pelvis
- uterine torsion, hydrops, placentitis
Fetal ( more common ):
- abnormal presentation/ posture/ position
- abnormal limb flexion/ tendon contracture
Outcome of dystocia
high risk of hypoxic foal and retained fetal membranes
Give PGF2a to:
lyse CL 5-6 days after it forms
What happens to the morula/ embryo between days 6-16 ?
Maternal recognition of pregnancy
What is best way to induce estrus in a mare within a CL > 6 days old seen on ultrasound ?
Administer PGF2a, will see estrus in at least 2 -5 days
Daily progesterone :
can be used to help synchronize estrus but needs to be administer daily for 12-15 days —> will see estrus in 4-5 days
hcG
used to induce ovulation of follicles > 35 mm
Does serum EcG and estrone sulfate detect pregnancy but do they distinguish between single fetus or twins?
Nope, they don’t distinguish between single fetus or twins
MC cause of dystocia
abnormal fetal presentation
Mare with normal foaling, when is the soonest she can be bred again?
in about 7-10 days (involutes rapidly)
Satisfactory pregnancy rate for a stallion performing live covers?
70% of 40 live covers
OR
120 AIs / season
Signs of placentitis
**premature udder development ** MC
vulvar discharge
Equine placentitis etiopathogenesis
- Diffuse ( Lepto, secondary to sepsis)
- Ascending from cervical start ( Strep zoo )
- Nocardioform ( Crosiella equi )
Diagnosis of placentitis
- transrectal U/S ( can see cervical star )
- transabdominal U/S (ID thickened placenta
+ evaluate fetal health )
Treatment of placentitis
- antibiotics
- progesterone
- pentoxifylline
- Flunixin meglumine
Outcome of placentitis
- abortion
- hypoxic foal
- normal foal
Equine uterine torsion
- occurs BEFORE parturition ( 5-11 months gestation )
- Does NOT involve cervix ( unlike cows )
- CS - colic, mild/ intermittent
- Dx - rectal palpation of broad ligaments ( one taut over uterus in direction of torsion)
-Tx - Surgery standing or under GA
OR roll under GA ( risk of uterine rupture )
Equine hydrops
RARE
- excessive accumulation of allantoic or amniotic fluid
- allantoic»_space; amniotic ( can’t palpate fetus)
CS - significant abdominal distention (days) , dyspnea, anorexia
Dx - CS + U/S to ID which cavity is affected
- R/O prepubic tendon rupture or hernia
Tx - Supportive care , +/- drain and induce parturition , +/- terminate pregnancy
Equine Red Bag
EMERGENCY
- premature separation of the chorioallantois
- can be secondary to placentitis
- CS/Dx - see RED BALL of tissue at vulvar lips = chorioallantois (* instead of normal amnion with fetal FL feet*)
- Patho - decreased oxygen to fetus
- Tx - rupture membranes ASAP w/ blunt object
- outcome - hypoxic foal
Retained fetal membranes more common after:
- abortion
- dystocia
- fetotomy
- C- section
Consequences of Retained fetal membranes in Mare
rapid development of endometritis, endotoxemia, and laminitis
Equine Uterine Artery Rupture
EMERGENCY
- OLDER, PLURIPAROUS mares
- at term, OR few weeks preterm, OR few days postpartum
- patho- uterine artery ruptures into broad ligament, uterus, or abdomen (hemoabdomen)
- CS - sweating, agitation , colic, pale mm –> obtundation and DEATH if progresses / bleeds out
- Dx - CS, ID hematoma/ hemoabdomen/ hemouterus with gentle uterine palpation OR ultrasound per rectum OR trans abdominal ultrasound
Treatment ( uterine artery rupture )
- ** keep mare quiet and calm ** most important
- Flunixin meglumine
- aminocaproic acid
- possibly low doses of acepromazine
- if bleeding out:
- naloxone
- blood transfusion
- Tx for shock ( hypertonic saline, etc)
Prognosis ( uterine artery rupture )
GUARDED , depends on where the bleed has occurred and extent of blood loss
Endometritis
(inflammation of endometrium)
causes:
Etiopath:
- recurrent contamination **
- reduced uterine resistance
- abnormal mechanical clearance
Common agents of Endometritis
- beta hemolytic streptococcus
- E.coli
- Pseudomonas
- Klebsiella
- Yeast
- Fungi ( aspergillus, Mucor )
CS of endometritis
- ** often no signs externally **
- sometimes vulvar discharge
- U/S –> uterine fluid, edema ( which is abnormal during diestrus )
- infertility
Endometritis Dx
- CS
- U/S
- uterine cytology or biopsy
- uterine culture
endometritis treatment
- FIRST correct any underlying factors
- sterile uterine lavage
- intrauterine antibiotic infusion
- Oxytocin IM or IV to evacuate uterus
- +/- short cycle with PGF2a
Outcome:
if untreated + persistent CL –> PYOMETRA ( leads to infertility, but no systemic signs )
Post partum metritis
Transient - common after parturition
- tx generally not needed
UNLESS mare is systemically ill - Dx - U/S per rectum
Post partum metritis (when to tx)
- mare is systemically ill
- if uterus is not involuting
- uterus contains fluid or discharge several days after giving birth
Tx ( post partum metritis ) If needed
- uterine lavage ( several Ls of sterile fluids)
- +/- intrauterine antibiotic infusion
- Oxytocin - to evacuate uterine contents
- Systemic NSAID
- Broad-spectrum antibiotics
- Exercise and foal nursing
Uterine torsion
typically occurs pre-term and does NOT involve the cervix ( unlike cows )
How to evaluate a mare with udder development 8 weeks prior to due date
- Ultrasound rectally and abdominally to evaluate the placenta
Can you palpate the cervix during late gestation
NOPE - it might lead to abortion or infection
5 hours post partum, Mare is pale, tachycardia, tachypneic, with cool extremities
what do you do? dx?
- minimize stress and perform a trans abdominal U/S
- most likely dx = ruptures uterine artery
- transrectal U/S may disrupt a clot
- large bolus of fluids is not appropriate –> may increase BP and disrupt any clot formation –> bleed out
Systemically healthy mare presents with mild reddish- brown vulvar discharge 3 days post foaling .
transrectal U/S - uterus is partially involved and there is minimal uterine fluid accumulation
what should you do?
- Nothing , this is normal lochia post foaling
- uterus is normal
