Equine - Pregnancy Loss and Pathologic Pregnancies Flashcards
When is pregnancy loss the most common?
in early pregnancy - within the first 35 days
15-20% of mares will lose pregnancy before day ____.
50
Up to 30% of mares will lose a pregnancy by _______.
foaling
What pregnancy losses are most commonly noted and detected by owners?
mid to late term losses
Pregnancy loss occurs frequently prior to the diagnosis of ______ particularly in _______ mares.
pregnancy; subfertile
What can cause pregnancy loss?
stress, endocrine imbalance, poor uterine environment
What stressors can cause pregnancy loss?
transport (not recommened until after 40 days of gestation), introduction to new groups, severe heat, significant work
What endocrine imbalances can cause pregnancy loss?
Cushing’s or Metabolic Syndrome
What disease processes can cause poor uterine environment that leads to pregnancy loss?
endometrial cysts, glandular fibrosis, and endometritis
True or False: Endometrial cysts can only cause late term pregnancy loss.
false- it can cause pregnancy loss at two different stages
How can endometrial cysts cause early pregnancy loss?
large intraluminal cysts can interfere with maternal recognition of pregnancy - interfere with embryonic movement
How can endometrial cysts cause mid to late-term pregnancy loss?
Large or multiple cysts may lead to placenta insufficiency
What can cause an increase in size and/or number of endometrial cysts?
lymphatic obstruciton, endometrial fibrosis, and endometrial glandular changes
How are endometrial cysts diagosed?
via transrectal ultrasonography
It is paramount to document what about endometrial cysts?
their size and location at the time of ovulation prior to pregnancy diagnosis
Where may endometrial cysts be located?
they may be luminal or intramural (lymphatic vs. glandular)
How can endometrial cysts be shaped?
ovoid, multilobular, or perfectly spherical
How are endometrial cysts treated?
hysteroscopic endometrial laser ablation
When can periglandular fibrosis cause pregnancy loss?
early, mid, or late-term losses
What age of mares typically get periglandular fibrosis?
older mares
What is periglandular fibrosis?
Increased layers of fibrocytes surrounding endometrial glands with glandular nesting
How is periglandular fibrosis diagnosed?
via endometrial biopsy
What % chance of foaling will a mare have if she is diagnosed with stage IIb periglandular fibrosis?
10-50% chance of foaling
What % chance of foaling will a mare have if she is diagnosed with stage III periglandular fibrosis?
<10% chance of foaling
What is the treatment for periglandular fibrosis?
none - the affected mares may be candidates for assisted reproductive techniques
What are some genetic and embryonic causes of pregnancy loss?
Embryonic factors, chromosomal abnormalities, genetic developmental abnormalities, and intrinsic factors with particular stallions and mares
What are some infectious causes of pregnancy loss and high-risk pregnancies?
endometritis (bacterial and fungal), placentitis (ascending, nocardioform, or hematogenous), leptospirosis, Equine Herpes Virus (EHV-1 and EHV-4), Equine Viral Arteritis Virus, and Potomac horse fever
What percentage of pregnancy loss is caused by placentitis and when does it occur?
20-30%, loss occurs late in gestation (8-10 months)
What are the types of placentitis?
ascending placentitis, hematogenous placentitis, and nocardioform placentitis
What is the most common type of placentitis and what is it caused by (general)?
ascending placentitis - multiple bacterial species are implicated
What is hematogenous placentitis an extension of?
bacteremia or viremia to seed the placenta leading to diffuse placentitis - may see clinical signs attributable to systemic infection in addition to abortion
What causes Nocardioform placentitis?
Amycolatopsis species, Crosiella equi, or Streptomyces species
What bacteria are commonly associated with ascending placentitis?
Streptococcus equi subsp. Zooepidemicus, E. coli, Klebsiella pneumoniae
What is the pathophysiology of ascending placentitis and fetal death.
There is bacterial colonization of the chorioallantois, then colonization and replication within the allantoic cavity, umbilicus, and amniotic fluid. This leads to increased inflammatory cytokines and prostaglandins. Uterine contractility is increased. There is an altered hormonal provile and activation of the HPA axis leading to abortion or delivery of premature, severely compromised foal.
True or False: Abortion due to placentitis often occurs without any premonitory signs.
TRUE
If a mare has clinical signs due to placentitis, what would they be?
early mammary development and/or secretions
How is placentitis diagnosed?
via transrectal ultrasound assessment of the combined thickness of the uterus and placenta (CTUP)
What should the CTUP be at days 271-300 of gestation?
<7 mm
What should the CTUP be at days 301-330 of gestation?
<10 mm
What should the CTUP be at greater than day 330 of gestation?
<12 mm
What is Nocardioform placentitis?
chorioallantoic thickening with thick exudate at the uterine body/base of gravid horns
The gross lesions of Nocardioform placentitis are ______.
pathognomonic
How is Nocardioform placentitis diagnosed?
Based on gross lesions, touch impression smear of chorioallantois, or PCR and/or histopathology BUT mainly increased CTUP
What does nocardioform placentitis result in?
premature delivery without fetal infection and/or sepsis - the foals exhibit signs of prematurity
What are some treatments for placentitis?
systemic antimicrobials, anti-inflammatories, and tocolytics
What systemic antimicrobials can be used to treat placentitis?
Trimethroprim sulfamethoxazole (TMS - abx of choice), Progaine penicillin (PPG)/potassium penicillin (K-PEN), and gentamicin
What anti-inflammatories can be used to treat placentitis?
flunixin meglumine (Banamine) and firocoxib (Equioxx)
What tocolytic can be used to treat placentitis?
altrenogest (Regumate)
What Leptospira species is the most common serotype in abortions?
L. kennewicki
How is leptospirosis transmitted?
contact with contaminated urine, aborted fetuses, and feed or water
When are abortions due to Leptospirosis often seen?
1-3 weeks after signs of maternal illness (fever, anorexia, jaundice, depression, renal disease, uveitis, etc.)
How is Leptospirosis diagnosed?
Serology, ID spirochetes in fetal kidney, placenta, or maternal urine, or FAT, IHC from placenta or fetal kidney
What may you see on necropsy due to leptospirosis?
you may see cystic nodular (adenomatous) allantoic hyperplasia
What is the treatment for leptospirosis?
maternal procaine penicillin or oxytetracycline - does not eliminate shedding
How is leptospirosis infection managed?
Isolate positive animals, prevent contact with swamp areas, contact with runoff water from cattle, pigs, dogs, and wildlife, and minimize rodent populations
What strains of equine herpes virus typically cause pregnancy loss?
EHV-1 and occasionally EHV-4
When do abortions due to EHV commonly occur?
in late term pregnancy - >6 months
Why is serology not valuable for diagnosis of EHV?
because the seroprevalence of EHV is 80% in equine populations
What will necropsy show in a fetus with EHV?
fresh fetus, with frequent focal hepatitis and pulmonary and placenta edema
What will histology show on a fetus with EHV?
intranuclear inclusion bodies in the lung, liver, thymus, and adrenals
How is EHV diagnosed at necropsy on a fetus?
FAT, virus isolation, PCR
How is EHV infection prevented during pregnancy?
vaccinate at 5, 7, and 9 months of gestation
How is EHV managed?
isolate pregnant mares from sick animals, group mares at similar stages of gestation;segregate farm by age, quarantine new arrivals for greater than 21 days prior to introduction in the herd, and hygiene-reduce fomite transmission
What is the major transmission method of Equine Viral Arteritis (EVA)? Minor?
major - venereal, inhalation
minor - vertical (in utero), horizontal (fomites, etc.)
What clinical signs may mares have due to EVA?
they are frequently asymptomatic or may have a mild fever, nasal discharge, and possible peripheral or cutaneous edema
What is the abortion rate due to EVA? When does it typically occur?
Abortion rate is 10-60%. It typically occurs in mid to late gestation
In the US, what breeds is abortion due to EVA prevalent in?
standardbreds
How is EVA diagnosed?
at necropsy (may see placental hemorrhage and edema due to vasculitis), virus isolation, RT-PCR, or serology of dam
What is the recommended treatment of EVA?
There is none - isolate and segregate EVA infected animals from non-vaccinated animals
How is EVA prevented?
early vaccination - isolate pregnant mares from individuals vaccinated for 30 days
What causes Potomac horse fever?
Neorickettsia risticii
How is Potomac horse fever transmitted?
ingestion of trematode intermediate host while drinking or grazing
What clinical signs are due to Potomac horse fever?
colitis, pyrexia, anorexia, diarrhea, illeus, laminitis, and abortion
How is Potomac horse fever diagnosed?
Response to treatment, PCR, +/- paired serology
How is Potomac horse fever treated?
Oxytetracycline
How is Potomac horse fever prevented?
vaccination and insecticides
What are the different forms of hydrops?
hydroallantois and hydroamnios
What is the most common form of hydrops and what is it due to?
hydroallantois due to abnormal placentation
What causes hydroamnios?
a defect in the fetal swallowing system
What is usually recommended with hydrops?
pregnancy termination or controlled drainage if attempt to maintain pregnancy to term
What is uterine torsion?
rotation of the uterus along its longitudinal axis due to increased fetal movement or sudden falls
When is uterine torsion most common?
in 7-9 months of gestation
What are the clinical signs associated with uterine torsion?
mild, intermittent, or acute severe colic
How is uterine torsion diagnosed?
rectal palpation or transrectal ultrasonography
How is uterine torsion diagnosed via rectal palpation?
identification of taught broad ligaments - direction of torsion
How is uterine torsion treated during pregnancy?
rolling with application of plank and person of moderate weight or surgical correction
What direction is a mare rolled in to relieve torsion?
In the direction of the torsion
What surgical correction can be done to resolve uterine torsion?
flank laparotomy or midline celiotomy
How is uterine torsion treated at foaling?
Derotation with a detorsion rod and controlled vaginal delivery or a C-section
What are the complications associated with uterine torsion?
placental detachment, premature placental separation (red bag), uterine wall necrosis, fetal death, adhesion formation (colic)
What is the most common cause of pregnancy loss in the UK (less common in the US)?
umbilical cord torsion
What is umbilical cord torsion due to?
increased fetal movement, hydrops conditions, long umbilical cords
Umbilical cord torsion is an umblrella term that covers what three processes to the cord?
torsion, ischemia, and/or necrosis
How many twists are normal to the umbilical cord?
4-7 twists
What will mammary secretions look like if there is a prepubic tendon/abdominal wall rupture?
hemorrhagic mammary secretions
What mares are predisposed to prepubic tendon/abdominal wall rupture?
Mares with hydrops, twins, or trauma
How are mares with prepubic tendon/abdominal wall rupture managed?
they are supported until foaling with a hernia belt and then either have assisted delivery or a C-section
What is the prognosis of a mare with prepubic tendon/abdominal wall rupture? Future fertility?
grave and grave
Many things can cause systemic compromise, what is the treatment of choice for this?
addressing underlying pathology and promote pregnancy maintenance (Regumate)
