Equine Pregnancy Problems Flashcards
1
Q
What hormones are involved in pregnancy
A
- Progesterone
- Estrogens
- eCG
- Relaxin
2
Q
Where does progesterone come from during pregnancy? How do these sources maintain pregnancy?
A
-
Ovarian source is essential for maintenance of pregnancy until ~day 100
- >1 ng/ml indicates presence of luteal tissue
- ≥ 4 ng/ml consistent with pregnancy
- <4 ng/ml if pregnant supplementation for pregnancy maintenance
- Primary CL formed from the follicle that ovulated the oocyte
- Progesterone levels peak around day 20 then decline until approximately days 40-45
- Secondary follicles and CL
- Development of endometrial cups occurs approximately days 35-38
- Functional until approximately day 120
- Production of equine chorionic gonadotropin (pregnant mare serum gonadotropin)
- expresses both TSH and LH-like activities resulting in secondary CL
-
Feto-placental progestogen production begins ~ day 70-80
- Generally sufficient to maintain pregnancy after day 100
- Low measurable maternal progesterone during this time
- Maternal progesterone may drop <4 ng/ml after sloughing of endometrial cups
- Progesterone peak just before foaling
3
Q
What hormones are responsible for pregnancy and fetal viability?
A
- Progestogens
- Estrogen - Estrone Sulfate
4
Q
What do the different changes in progestogen levels mean?
A
- Progestogens
- Assays for progestogens produced by fetoplacental unit are not readily available
- Some commercial P4 assays will cross-react
- Rapid Decline (acute cases)
- frequently seen in acute conditions where fetal death has occurred or expulsion is imminent
- Precocious Rise (Chronic cases)
- associated with fetal stress or placental pathology
- Elevations for 2-3wks prior to day 310-320 are more likely to deliver live foals
- Linked to accelerated adrenal gland maturation thus increasing production of fetal progestins leading to increased peripheral progestins in circulation
5
Q
Where is estrogen sourced from during pregnancy? what do the levels mean?
A
- After day 55 - source form fetal-placental unit
- After 3rd month of pregnancy good marker of fetal viability
- Fetal death leads to rapid decline in estrogen levels within a few days
6
Q
What is placentitis?
A
- leading cause of:
- abortion
- premature birth
- still birth
- hypoxic or septicemic foals
- Infection of the placenta
- ascending infection of bacteria
- transcervical
- Diffuse
- hematogenous
- ascending infection of bacteria
7
Q
What is the clinical presentation of placentitis?
A
- Premature udder development
- Premature lactation
- +/- vaginal discharge
- Spontaneous abortion
- Birth of septic/hypoxic
8
Q
What causes Ascending placentitis?
A
- Associated with poor anatomical barriers
- Poor perineal confirmation
- Poor cervical function/tone
- Bacteria
- S. zooepidemicus
- E. coli
- K. pneumoniae
- P. aeruginosa
- Fungal
- Aspergillus sp.
9
Q
What is Ascending placentitis? what symptoms?
A
- Organisms originate form the vagina, skin, feces, or environment
- Ascends through the cervix to the cervical star
- Depleted area of villi
- Thickened
- Discolored
- Fibronecrotic exudate
10
Q
How can placentitis be diagnosed pre-partum?
A
- External clinical signs
- premature udder development
- premature lactation
- vaginal discharge
- Culture and sensitivity of vaginal discharge of from external cervical os
- Combined utero-placental thickness
- endocrine testing
- Blood progesterone
- estrogens
11
Q
How is combined utero-placental thickness measured?
A
- Performed at the caudal allantochorion
- Cranial of the cervical-placental junction
- landmark
- middle branch of the uterine artery along the ventral aspect of the uterine body
- Measure:
- caudal, ventral edge of the uterus between the middle branch of the uterine artery and the allantoic fluid
12
Q
How is fetal stress assessed using transabdominal US?
A
- Assess fetal well-being
- normal HR during late gestation ~80 bpm (60-110)
- Consistently low or high are associated with fetal stress
- Evaluate for areas of placental separation
- Echogenicity of fetal fluids
- Fetal activity
13
Q
What are the treatments for placentitis?
A
- Prolong gestation as long as possible: ≥ 320 days
- Chronic in-utero stress leads to accelerated fetal maturation
- Broad spectrum antibiotics
- Trimethoprim-sulfonamide 30 mg/kg PO BID
- Penicillin and gentamicin
- Anti-inflammatory
- Flunixin meglumine 1.1 mg/kg IV or PO for 7 days
- Promote uterine quiescence
- altrenogest 0.044 PO BID or 0.088 mg/kg PO SID
- Anti-endotoxic and rheologic
- pentoxifylline 8.4 mg/kg PO TID-QID
- Anti-oxidant
- Vitamin E
14
Q
What causes hematogenous placentitis?
A
- Leptospira interogans spp (multiple serovars)
- Nocardioform actinomycete
- Crossiella equi or Amycolatopis spp
15
Q
What happens in hematogenous placentitis caused by leptospira interrogans spp.?
A
- subspecies pomona - most abortions
- Mare is typically systemically ill
- Infects the fetus hematogenously
- results in abortion, stillbirth, premature live birth
- Dx: Placenta - spirochetes on silver stain
16
Q
What happens in hematogenous placentitis caused by nocardia actinomycete
A
- Crossiella equi or Amycolatopis spp
- Characteristic placentitis
- Thick, brown mucoid exudate at the jungiton between the gravid horn and the body
- Dx: confirm with culture
17
Q
What are the different events that result in mares being pregnant with twins? why?
A
- Two eggs, Two ovulations: dizygotic twins
- Different genomes
- synchronous and asynchronous ovulations
- higher incidence in TB, draft and warmblood mares
- Higher incidence with ovulatory drugs
- One egg, one ovulation: monozygotic twins
- splitting of a single fertilized ovum
- Identical genomes
- Two eggs, one ovulation: dizygotic twins
- different genomes
18
Q
What are the possible outcomes of twin pregnancies in mares?
A
- Mare reduction of twins to single pregnancy
- Unilateral fixation: 70-89% reductions
- Bilateral fixation: 4-30% reduction
- Late Term abortion: 64.5%
- placenta contact with the uterus becomes insufficient to maintain fetal life
- Premature udder development/lactation
- Dystocia/neonatal death
- Birth of small, growth retardd foals
19
Q
How are twin pregnancies diagnosed?
A
- Transrectal US: ideally 14 days post-ovulation
- Prior to fixation
- Cysts or twins?
- Embryo changes location
- Embryo grows 3 -4 mm/day
- Transabdominal US: >80-90 days post-ovulation
- different location, orientation, HR, size
20
Q
How can twin pregnancies be reduced by vets?
A
- Pinching
- US-guided allantocentesis
- US-guided fetal cardiac puncture
- Cranio-cervical dislocation
21
Q
What is the success of medically reducing twins in mares (besides pinching)
A
50% of mares maintain the remaining fetus
22
Q
What is the process of “Pinching”
A
- 90-95% success rate of mares carrying the remaining fetus to term
- Bilateral horns or manual separation prior to fixation
- Pre-treat mare with NSAIDs & for 3-4 days
- Pre-treat and maintain on progesterone for 10-14 days
- Re-evaluate remaining vesicle 2-3 days post pinching
- Monitor progesterone levels
23
Q
What is Equine Herpesvirus Abortion? How can this be prevented?
A
- EHV-1 & EHV-4
- EHV-1 most common infectious cause of abortion
- Highly contagious, transmission usually through respiratoy
- Latency
- Usually later term abortion (7mo - term)) may occur 2 wks to months post-infection
- Mares abort suddenly w/out signs
- Aborted fets normally fresh
- Submit paired serum samples form mare and fetus plus fetal membranes
- Foals may be born stillborn or weak or appear normal thn become clinical w/in 1-3 days
- Mares recover with short-lived immunity, but future fertility is not compromised
- Prevention
- management
- Vaccinate mares at (3), 5, 7, & ( months of gestation with modified live or killed EHV-1
- pneumabort-K or Prodigy
24
Q
What is Equine Viral Arteritis? How does it cause abortion?
A
- Abortion typically occurs 7-10 days following maternal illness
- leukopenia, serous nasal discharge, ocular discharge, conjunctivitis, edema of limbs and ventral abdomen, petechiation, and fever
- +/- respiratory signs
- Aborted fetus is often autolytic but may be fresh
- most occur between 5-10mo gestation
- Transmission:
- Aerosolized
- Venereal: Mare ⇠⇢ stallion, semen, aborted tissues, placenta and fetus
- Stallions may become long-term carriers
- Infected/shedding stallions may be bred to seropositive or vaccinated mares
- strict isolation for 3 wks following breeding to prevent shedding to naïve horses
- Vaccination: modified live
- serotest stallions prior to initial vaccination and vaccinate annually
25
What is Mare Reproductive Loss Syndrome?
* Pathogenesis: Unknown
* Ingestion of **Eastern Tent Caterpillar**
* Barbed setae on cuticle that may contain bacteria penetrate the intestine and distribute hematogenously throughout the mare
* Foals: early fetal loss, late fetal loss, pericarditis, pneumonia, umbilical cord inflammation, neurological disease, asphyxia
* Adults: placental separation (red bag), pericarditis and uveitis
26
What is fescue toxicity? How does it affect pregnancy? how can it be prevented/treated?
* *Acremonium* contaminated fescue
* ergot alkaloids act as dopamine receptor agonists (low circulating prolactin)
* agalactia and FPT
* Pregnancy affects:
* Thickened placenta
* Prolonged gestation
* Decreased relaxin
* Large dysmature foals
* Dystocia
* Abortion or neonatal death
* Retained placenta
* Tx:
* Dopamine antagonists
* domperidone, sulpiride
* Starting 1mo prior to foaling
* Prevention:
* Pasture management to control infestation
* Supplemental feeding of non-fescue hay
* Endophyte free fescue
* Remove from pasture 90 days prior to foaling
27
What are causes of abdominal enlargement during pregnancy (not the baby!)
* Ventral edema
* Prepubic tendon rupture
* Hydrops allantois
* Hydrops amnion
28
Why does Prepubic tenon rupture occur? what happens after?
* Occurs:
* late gestation
* predisposed mares - hydrops, twins, lack of muscle tone
* Post rupture:
* Present with abdominal pain and reluctance to walk
* Abdomen is dependent ventrolateral and has thick plaque of edema
* Udder loses support, blood vessels in the mammary gland can rupture resulting in blood in the milk
* Treatment:
* abdominal support
* induced assisted foaling
* C-section
* Poor Prognosis
* Mares should **not** carry future pregnancies
29
What is Hydroallantois?
* Thought to develop as a result of placental dysfunction
* increase production of transudateDisruption of transplacental fluid absorption
* Excess allantoic fluid (100-200 liters)
* Fast distension over 10-14 days
* Typically present after 7th month of gestation
* Dx:
* excessive abdominal enlargement
* large fluid filled uterus
* reluctance to walk, dyspnea, altered gait
30
What are the possible sequelae of hydroallantois
* uterine rupture
* abdominal muscle rupture
* inguinal herniation
* abortion, stillbirth
* uterine inertia
* hypovolemic shock
* retained placenta
31
What is the treatment for Hydroallantois
* Induce abortion
* pre-treat with IV fluids
* Manual cervical dilation
* Puncture membranes
* slow fluid drainage
* Manual extraction of the fetus
* hypovolemic shock
32
What is the affect of hydroallantois on future fertility?
* Good prognosis
