Early Pregnancy: Pre-fixation (before day 16) events
• Selective transport of fertilized ova (PGE) • Embryo reaches the uterus at the blastocyst stage about 6 days after fertilization • Blastocyst expands and forms the vesicle • Transuterine migration provides signals preventing luteolysis
Early Pregnancy: Fixation
• 16-17 days • Fixation of the embryo does not occur necessarily in the horn ipsilateral to the CL bearing ovary • Day 35 formation of the endometrial cups
endometrial cups form on what day?
day 35
Pregnancy: Placentation
• Development of villi starts by day 45 covering the entire chorioallantoic surface and interdigitate with corresponding endometrial • Microcotyledonary, diffuse
Emergencies in pregnancy
• Colic in the pregnant mare • Abnormal vaginal discharge • Premature mammary gland development or lactation • Ventral abdominal wall abnormalities
Signs of impending pregnancy loss
• Irregular and indented vesicle
• Fluid in the uterine lumen
• Echogenic spots (speckling) of the embryonic vesicle
• No fetal heartbeat
• Poor definition of fetal structures
• Increased echogenicity of fetal fluid
• Largest diameter of the fetal vesicle is 2 standard deviation
smaller that the mean of the age of pregnancy
• Slow growth in size
• Failure of fixation
• Echogenic ring within the vesicle
• Disorganized membranes and collapsed amnion
• Increase edema and exaggerated endometrial folds
• Presence of fluid surrounding the embryonic vesicle
Ultrasonography - diagnosis of pregnancy problems- approach
• Fetus Heart rate and rhythm Size and number Fetal activity Fetal tone • Quantity and quality of allantoic and amniotic fluid • Fetal membranes/ Thickness of the uteroplacental unit
Fetal heart rate
• 1.5 to 1.8 x that of the dam • Faster in early pregnancy • Decreases from 120 bpm in the first 3 months to 60 bpm in the last couple of weeks • Increases in response to fetal activity by 25 to 40 beats • Fetal activity and increased heart responses occur 48 to 72 hours prior to parturition
fetal biometrics
• Aorta systolic diameter • Biparietal diameter • Eye volume • Kidney cross sectional area
Evaluation of the placenta: Transabdominal
• Epitheliochorial, covers the entire uterus except at the level of the cervical star • Examination percutaneous and per rectum • Focus of the examination Combined uteroplacental thickness
Combined uteroplacental thickness (CUPT) - where is it measured
• 3 to 5 cm cranial to the cervix
between the middle branch of the
uterine artery and the allantoic fluid
Endocrine evaluation - Progesterone/Progestogen
Main source in the first trimester : Ovary
Main source past 80 days is the placenta
– Convert pregnenolone to progesterone
– Progestin (5 α pregnanes)
• Decreased myometrial activity and prevent abortion
• Progesterone peaks 24 to 48 hours prior to parturition
Endocrine evaluation - Estrogens
• Total estrogens should be > 1000 pg/ml
Features of fetal stress
• Persistent fetal tachycardia or bradycardia
• Large or progressively enlarging areas of
placental detachment
• Rapid drop in progestins (Houghton et al 1991,
Rossdale et al 1991)
Features of death or imminent abortion
• Large of progressively enlarging areas of
placental detachment
• Premature mammary development and lactation
Management of compromised pregnancy
- Limit effect of prostaglandin (NSAID)
- Ensure myometrial quiescence
- Antibiotics (placentitis)
- Improve oxygenation and reduce effect of inflammation byproducts
- Support fetal metabolism
Bacterial placentitis isolates
• Streptococcus spp. (S. zooepidemicus) • Staphylococcus spp. • E.coli • Klebsiella spp • Enterobacter spp. • Pseudomonas spp. • Salmonella abortus equi
Ascending placentitis causes abortion between what months of gestation?
6 and 9
• S. equi subsp. zooepidemicus
placentitis appearance
acute and focal or diffuse
ascending placentitis - bacteria
S. equi subsp. zooepidemicus
E. Coli
Psuedomonas aeruginosa
Escherichia coli placentitis
Usually acute before 7 months
chronic and focally extensive,
involving the cervical star, after 9
months of gestation
Pseudomonas aeruginosa
placentitis
Either focal or diffuse with a
thickened and discolored cervical
star
Dx of bacterial placentitis
clinical signs
transrectal ultrasonography
bacteriology
clinical signs of bacterial placentitis
Premature udder development or lactation Vaginal discharge Asymptomatic
• Transrectal
Ultrasonography finding with bacterial placentitis
Increased CUPT
Areas of placental
separation
Features of placentitis in the dam
- Premature mammary gland development
* Mucopurulent vaginal discharge (ascendant placentitis
Features of placentitis in the fetus
•Persistent fetal tachycardia
Features of placentitis in the uteroplacental unit
- Thickening of the uterine wall (>13 mm)
- Increased CUPT (>17.5 mm)
- Pockets of hyperechoic fluids (pus)
- Areas of placental separation
Features of placentitis - endocrinology
•Increased total progestogen concentration
•Decreased total estrogens
•Elevation of acute phase proteins (Serum amyloid A and
Haptoglobin)
Leptospirosis locations
• More frequently
diagnosed in Kentucky,
Florida and South
America
Leptospirosis – Clinical presentation
• Clinical signs in the mare not always present • Fever • Hematuria • Acute renal failure • Uveitis may develop weeks after abortion • Stillborn or weak foals • Abortion
Abortion occurs when with lepto?
• Mid to late term abortion
(most in the last 3 months of
gestation)
• Not all infected mares abort
Leptospirosis – Pathological findings placenta
• Placentitis not involving cervical star • Heavy, edematous, hemorrhagic • Occasionally covered with a brown mucoid material on the chorionic surface • Calcification • Funisitis in some cases
Leptospirosis – Pathological findings fetus
• Mild to moderate icterus
• Liver enlargement, hepatitis
• Tubulonephrosis and
interstitial nephritis
Leptospirosis - Diagnosis
• Fetal and placental lesions
• Fetal antibodies
• Isolation from placenta or renal tubules
• Immunohistochemistry of the placenta umbilical
cord or fetal kidney and liver
• PCR
• High-titers agglutinating antibody in mare
(>1:6,400 often > 12,800)
Leptospirosis - Prevention
• Isolation of aborting mare for 14 to 16 weeks
• Urine testing by FAT for shedding
• Treatment of possible shedders??
Antibiotic treatment (Oxytetracycline 5 mg/kg, IV,
SID or penicillin G, 20,000 IU/kg IM BID) for 5 to 10
days has been reported to help prevent abortion
during an outbreak
• Limit exposure to stagnant water
• Control of reservoir animals
• Vaccine is available
Nocardioform placentitis
• Chronic placentitis • Late term abortion or premature birth • Severe exudative, mucopurulent, and necrotizing placentitis at the junction of the placental body and horns • Fetus severely underdeveloped
Nocardioform placentitis - most severe infections are caused by what?
actinomycete Crossiella equi
EHV transmission
• Transmission: • Respiratory • Abortion may be stress related • May occur in vaccinated mares (reactivation of latent infection
When does abortion occur with EHV?
• Abortion usually 7 months to term
• Abortion- fresh fetus
• Fetuses > 8 moths present characteristic
lesions particularly with EHV-1
Diagnosis of EHV abortion
Necropsy • Rib impression • Focal necrosis in the liver • Presence of pleural fluid • Fibrin in the trachea • Vascular necrosis • Intra-nuclear inclusion Laboratory • Virus isolation • Immunochemistry, or polymerase chain reaction (PCR) on fetal lung, liver, spleen, and thymus
prevention of EHV abortion
• Vaccination (killed vaccine at
5, 7, 9 months)
• Separation of pregnant mares
from high risk horses
Equine viral arteritis (EVA)
non arthropod-borne virus of
togaviridae family
EVA transmission
primarily respiratory and
venereal, fecal and urinary possible
Abortion with EVA
• Abortion, usually 5 mos. to term or 20-40
days post-exposure, up to 50-70% of infected
mares may abort
• Fetus and placenta in variable degree of
autolysis
Clinical signs of EVA
• Clinical signs: Limb edema, lameness, nasal and
ocular discharge, conjunctivitis, facial edema,
preputial edema, urticaria, pyrexia, depression and
anorexia
• Fetus
• Subcutaneous edema
• Petichial hemorrhages in the pleura and epicardium
• Increased pleural fluid
lab dx of EVA
• Seroconversion • Virus isolation: nasal swabs, buffy coat, urine or semen of adult, placenta, spleen of fetus • Immunohistochemistry • PCR
Prevention and control of EVA
Test stallions / teasers • Require negative status (AI) • Vaccination MLV Stallions NON-PREGNANT MARES Always separate vaccinated animals from pregnant mare for at least 30 days
Fungal Abortion
• Aspergillus fumigatus and Mucor spp most
commonly but others also involved
• Usually ascending, some hematogenous
• Chorion may be dry and leathery or have a
brown, tenacious exudate, especially at the
cervical area
Protozoal Abortion
- Neospora spp.
- Trypanosoma equiperdum (dourine)
- Babesia equi or caballi (piroplasmosis)
Mare Reproductive Loss Syndrome associated with what?
Eastern tent caterpillar and placental edema
Non-infectious Abortion
- Twinning**
- Umbilical cord torsion**
- Progesterone deficiency
- Stress due to illness, trauma, transport
- Chromosomal or genetic abnormalities
- Fetal abnormalities
- Placental insufficiency or abnormalities
Twinning in the mare
The leading cause of non infectious abortion (Thoroughbred, Warmblood) • All (almost all) equine twins are dizygotic • Double ovulations
Twinning - Diagnosis
• Ultrasonography Transrectal Transabdominal ECG • Source of errors Stage of development Uterine cysts
Management of twin pregnancies
• Before fixation crushing, 100% effective if twins are separated No effect on pregnancy if done properly • After fixation Bilateral: crushing Unilateral: – Wait and see – Play the odds
Management of twin pregnancies - past 30 days
Transvaginal ultrasoundguided aspiration Intra-cardiac injection Wait and see Abort both and loose season
Management of twin pregnancies
• Past 65 days:
Transabdominal Intracardiac injection Cervical dislocation Surgical removal Abort both and loose season Complications
Prevention of twin pregnancies
• Check mare during estrus for double follicles • Predisposed breeds! • Check for pregnancy early and often • Manual crushing (easier said than done!)
Uterine Torsion
• Colic varying degree of intensity or just ADR • Essential rule out in any case of colic in pregnant mares (>5 months) • Diagnosis based on transrectal palpation • History Fetal and placental evaluation important for choice of method of correction
Non-surgical correction of uterine torsion: Rolling
• General anesthesia • Mare is place on lateral recumbency on the side of torsion • Plank on the opposite side • Roll at least 3 times • Check in sternal position
Surgical correction of uterine torsion
midline laparotomy
Hydrops allantois
Excessive accumulation of allantoic
fluid
Hydrops amnii
Excessive amount of amniotic fluid,
edematous umbilical cord, abnormal
fetus
Hydrallantois - Hydramnios - causes
- Abnormal placentation
- Abnormal umbilical cord
- Lack of swallowing of liquid fluid
- Overproduction of fluid
- Fetal abnormalities
- Genetics
Hydrallantois - Hydramnios - dx
Clinical signs, palpation, girth
measurement
Hydrallantois - Hydramnios - tx
- Induction of abortion/parturition
- Conservative management
- Humane euthanasia
Prolonged Gestation due to Fescue Tox
• Endophyte: Acremonium coenophialum • Alkaloids: Ergovaline, Loline • Endocrine effects • Low plasma progesterone concentration • Low relaxin level
Clinical effects of fescue tox
• Placental edema thickening • Premature placental separation (Red bag) • Abortion • Agalactia • Weak /immature foals
Tx/Px of Fescue Tox
- Remove from pasture
* Domperidone
Prolonged Gestation
Congenital hypothyroid dysmaturity syndrome - cause
- Mustard toxicity
* Brassica spp
Endocrine effects of brassica tox
• Glucosinolates broken down into
thiocyanates and thiouracil
analogs are goitrogenic
Clinical effects of mustard tox
• Poor development (prematurity signs) • Incomplete ossification of the cuboidal bones • Flexural deformities of the forelimbs • Ruptured digital extensors • Hydrocephalus, patent urachus
Prolonged Gestation
Intrauterine growth retardation - cause
- Poor nutrition
- Abnormal placentation
- Fetal abnormalities
Bloody vaginal discharge
• Impending abortion
• Hemorrhage from
varicose veins
Differential diagnosis of body wall defects
• Severe ventral edema • Hernia • Prepubic tendon rupture • Rupture of the mammary ligament • Udder edema
Management of mares with body wall defects
• Confine / control exercise • Control food and water intake • Symptomatic treatment in case of ventral wall edema • Support body wall • Pain management • Close monitoring for foaling • Induction of parturition when appropriate