Disorders of Pregnancy in the Mare Flashcards
1
Q
Early Pregnancy: Pre-fixation (before day 16) events
A
• 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
2
Q
Early Pregnancy: Fixation
A
• 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
3
Q
endometrial cups form on what day?
A
day 35
4
Q
Pregnancy: Placentation
A
• Development of villi starts by day 45 covering the entire chorioallantoic surface and interdigitate with corresponding endometrial • Microcotyledonary, diffuse
5
Q
Emergencies in pregnancy
A
• Colic in the pregnant mare • Abnormal vaginal discharge • Premature mammary gland development or lactation • Ventral abdominal wall abnormalities
6
Q
Signs of impending pregnancy loss
A
• 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
7
Q
Ultrasonography - diagnosis of pregnancy problems- approach
A
• 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
8
Q
Fetal heart rate
A
• 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
9
Q
fetal biometrics
A
• Aorta systolic diameter • Biparietal diameter • Eye volume • Kidney cross sectional area
10
Q
Evaluation of the placenta: Transabdominal
A
• 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
11
Q
Combined uteroplacental thickness (CUPT) - where is it measured
A
• 3 to 5 cm cranial to the cervix
between the middle branch of the
uterine artery and the allantoic fluid
12
Q
Endocrine evaluation - Progesterone/Progestogen
A
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
13
Q
Endocrine evaluation - Estrogens
A
• Total estrogens should be > 1000 pg/ml
14
Q
Features of fetal stress
A
• 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)
15
Q
Features of death or imminent abortion
A
• Large of progressively enlarging areas of
placental detachment
• Premature mammary development and lactation
16
Q
Management of compromised pregnancy
A
- Limit effect of prostaglandin (NSAID)
- Ensure myometrial quiescence
- Antibiotics (placentitis)
- Improve oxygenation and reduce effect of inflammation byproducts
- Support fetal metabolism
17
Q
Bacterial placentitis isolates
A
• Streptococcus spp. (S. zooepidemicus) • Staphylococcus spp. • E.coli • Klebsiella spp • Enterobacter spp. • Pseudomonas spp. • Salmonella abortus equi
18
Q
Ascending placentitis causes abortion between what months of gestation?
A
6 and 9
19
Q
• S. equi subsp. zooepidemicus
placentitis appearance
A
acute and focal or diffuse
20
Q
ascending placentitis - bacteria
A
S. equi subsp. zooepidemicus
E. Coli
Psuedomonas aeruginosa
21
Q
Escherichia coli placentitis
A
Usually acute before 7 months
chronic and focally extensive,
involving the cervical star, after 9
months of gestation
22
Q
Pseudomonas aeruginosa
placentitis
A
Either focal or diffuse with a
thickened and discolored cervical
star
23
Q
Dx of bacterial placentitis
A
clinical signs
transrectal ultrasonography
bacteriology
24
Q
clinical signs of bacterial placentitis
A
Premature udder development or lactation Vaginal discharge Asymptomatic
25
• Transrectal
| Ultrasonography finding with bacterial placentitis
Increased CUPT
Areas of placental
separation
26
Features of placentitis in the dam
* Premature mammary gland development
| * Mucopurulent vaginal discharge (ascendant placentitis
27
Features of placentitis in the fetus
•Persistent fetal tachycardia
28
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
29
Features of placentitis - endocrinology
•Increased total progestogen concentration
•Decreased total estrogens
•Elevation of acute phase proteins (Serum amyloid A and
Haptoglobin)
30
Leptospirosis locations
• More frequently
diagnosed in Kentucky,
Florida and South
America
31
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
```
32
Abortion occurs when with lepto?
• Mid to late term abortion
(most in the last 3 months of
gestation)
• Not all infected mares abort
33
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
```
34
Leptospirosis – Pathological findings fetus
• Mild to moderate icterus
• Liver enlargement, hepatitis
• Tubulonephrosis and
interstitial nephritis
35
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)
36
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
37
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
```
38
Nocardioform placentitis - most severe infections are caused by what?
actinomycete Crossiella equi
39
EHV transmission
```
• Transmission:
• Respiratory
• Abortion may be stress related
• May occur in vaccinated mares (reactivation of
latent infection
```
40
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
41
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
```
42
prevention of EHV abortion
• Vaccination (killed vaccine at
5, 7, 9 months)
• Separation of pregnant mares
from high risk horses
43
Equine viral arteritis (EVA)
non arthropod-borne virus of
| togaviridae family
44
EVA transmission
primarily respiratory and
| venereal, fecal and urinary possible
45
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
46
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
47
lab dx of EVA
```
• Seroconversion
• Virus isolation: nasal swabs, buffy coat, urine or semen of
adult, placenta, spleen of fetus
• Immunohistochemistry
• PCR
```
48
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
```
49
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
50
Protozoal Abortion
* Neospora spp.
* Trypanosoma equiperdum (dourine)
* Babesia equi or caballi (piroplasmosis)
51
Mare Reproductive Loss Syndrome associated with what?
Eastern tent caterpillar and placental edema
52
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
53
Twinning in the mare
```
The leading cause of non
infectious abortion
(Thoroughbred, Warmblood)
• All (almost all) equine twins are
dizygotic
• Double ovulations
```
54
Twinning - Diagnosis
```
• Ultrasonography
Transrectal
Transabdominal
ECG
• Source of errors
Stage of development
Uterine cysts
```
55
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
```
56
Management of twin pregnancies - past 30 days
```
Transvaginal ultrasoundguided
aspiration
Intra-cardiac injection
Wait and see
Abort both and loose
season
```
57
Management of twin pregnancies
| • Past 65 days:
```
Transabdominal Intracardiac
injection
Cervical dislocation
Surgical removal
Abort both and loose
season
Complications
```
58
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!)
```
59
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
```
60
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
```
61
Surgical correction of uterine torsion
midline laparotomy
62
Hydrops allantois
Excessive accumulation of allantoic
| fluid
63
Hydrops amnii
Excessive amount of amniotic fluid,
edematous umbilical cord, abnormal
fetus
64
Hydrallantois - Hydramnios - causes
* Abnormal placentation
* Abnormal umbilical cord
* Lack of swallowing of liquid fluid
* Overproduction of fluid
* Fetal abnormalities
* Genetics
65
Hydrallantois - Hydramnios - dx
Clinical signs, palpation, girth
| measurement
66
Hydrallantois - Hydramnios - tx
* Induction of abortion/parturition
* Conservative management
* Humane euthanasia
67
Prolonged Gestation due to Fescue Tox
```
• Endophyte: Acremonium
coenophialum
• Alkaloids: Ergovaline, Loline
• Endocrine effects
• Low plasma progesterone
concentration
• Low relaxin level
```
68
Clinical effects of fescue tox
```
• Placental edema thickening
• Premature placental
separation (Red bag)
• Abortion
• Agalactia
• Weak /immature foals
```
69
Tx/Px of Fescue Tox
* Remove from pasture
| * Domperidone
70
Prolonged Gestation
| Congenital hypothyroid dysmaturity syndrome - cause
* Mustard toxicity
| * Brassica spp
71
Endocrine effects of brassica tox
• Glucosinolates broken down into
thiocyanates and thiouracil
analogs are goitrogenic
72
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
```
73
Prolonged Gestation
| Intrauterine growth retardation - cause
* Poor nutrition
* Abnormal placentation
* Fetal abnormalities
74
Bloody vaginal discharge
• Impending abortion
• Hemorrhage from
varicose veins
75
Differential diagnosis of body wall defects
```
• Severe ventral edema
• Hernia
• Prepubic tendon
rupture
• Rupture of the
mammary ligament
• Udder edema
```
76
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
```
