1. FIRST POTENTIAL CASE OF NOCARDIOFORM PLACENTITIS IN
A MARE FROM ALABAMA
S.M. Shrader1
, J.C. Newton1
, R.R. Wilborn2
. 1
Department of Pathobiology and 2
Department of Clinical Sciences, Auburn University, Auburn, AL
Clinical History
A 14-year-old Warm Blood mare from Tallapoosa County, AL presented to the Auburn University Large Animal
Teaching Hospital Theriogenology service in April 2012 for a breeding soundness examination. The horse had
previously foaled twice. Examination indicated that she was a good candidate for breeding. On May 14th
, she
was inseminated using a deep uterine horn insemination technique with the first dose of frozen semen, ovulat-
ed overnight, and was administered the second dose of frozen semen the following morning. A follow-up exami-
nation indicated that she was not pregnant. On June 4th
, she was artificially inseminated in the left uterine horn
with fresh semen from one of the stallions at the AU Theriogenology center. Pregnancy was confirmed on July
9th
and the expected due date was May 31st
, 2013. The pregnancy was unenventful until she presented on Mar
26th
, 2013 for udder development (day 275 of gestation). At that time she lacked vaginal discharge and cervical
dilation; however, treatment for suspected placentitis was initiated (consisting of trimethoprim sulfa, flunixin
meglamine and altrenogest). Premature labor occurred on April 10th
(at 290 days gestation). The mare delivered
a live foal (that was subsequently euthanized).
Discussion
The underlying etiology of the chorionitis in this case remains undetermined; however, the late-term
abortion, well-demarcated avillous chorionic surface and intralesional branching filamentous Gram
positive bacilli are consistent with previous reports of nocardioform placentitis[1]. Nocardioform pla-
centitis is the predominant cause of placentitis and reproductive loss in central Kentucky[2] and is as-
sociated with species in the genus Amycolatopsis[3] and Crossiella equi[4]. This form of placentitis
has also been confirmed in a mare and stallion in Florida and a mare and stallion in Virginia[1]. The
pathogenesis of nocardioform placentitis continues to be debated. In general, there are two main
routes of placental infection: hematogenous spread or ascension of infection from the cervix. Hema-
togenous spread seems unlikely in this instance because in all reported cases, the nocardioform bac-
teria result in a focal lesion. An ascending infection does not seem likely either because the microvilli
surrounding the cervical star are unaffected.
Abstract
A 14-year-old Warm Blood mare from Tallapoosa County, AL presented to the Auburn College of Veteri-
nary Medicine at 275 days gestation with premature udder development. Therapy, consisting of altreno-
gest and trimethoprim/sulfamethoxazole, were initiated for suspected placentitis; however, premature la-
bor occurred at 290 days gestation. The mare delivered a live foal (that was subsequently euthanized)
and the entire placenta was submitted for gross and histopathological examination. On gross examina-
tion, the chorionic surface had a 30-cm x 40-cm, well-demarcated, pale pink-yellow area surrounded by
hyperemia. In some areas, the line of demarcation was associated with and obscured by yellowish
plaques. On the allantoic side, adjacent to the umbilical cord-associated vasculature, were numerous,
variably sized (up to 9-cm in diameter), ovoid to irregularly shaped, firm, mottled red nodules (consistent
with adenomatous hyperplasia). Histologically, the chorion had a focally extensive avillous area that was
associated with a surface of degenerate epithelium. Along the periphery of this area, there were degen-
erate and necrotic trophoblasts with a mixed inflammatory infiltrate and numerous, variably sized, Gram
positive bacilli, including some with filamentous branching. Aerobic bacterial cultures confirmed the pres-
ence of numerous Gram positive bacilli. PCR was performed on a placental swab (submitted to the Uni-
versity of Kentucky Veterinary Diagnostic Laboratory) to test for the presence of Amycolatopsis spp. and
Crossiella equi (nocardioforms known to cause placentitis in mares from Kentucky and Florida). Results
were negative. Although neither of the previously reported nocardioforms was identified, based on the
late gestational premature labor, gross findings, and histopathological observation of placentitis with in-
tralesional Gram positive filamentous bacteria, this case represents the first potential occurrence of eq-
uine nocardioform placentitis in Alabama. Diagnostics
Bacteriology:
A uterine culture, performed immediately following premature labor, revealed growth of unspeci-
fied Bacillus spp. Frozen serum from the mare, placental and uterine swabs and placental exudate
were also submitted to the University of Kentucky College of Agriculture Veterinary Diagnostics La-
boratory. Their laboratory confirmed the presence of an unclassified Gram positive bacillus
(consistent with Bacillus spp). Additionally, PCR was performed for the detection of Amycolatopsis
and Crossiella equi (nocardioforms previously isolated from cases of equine placentitis); however,
neither pathogen was detected. She was subsequently re-cultured on May 3rd
and was found to be
negative for bacterial growth.
Gross Placental Examination:
The entire placenta was received for examination. On the allantoic side of the chorioallantois, adja-
cent to umbilical cord-associated vasculature, were numerous, variably sized (up to 9-cm in diame-
ter), ovoid to irregularly shaped, firm nodules with pale to dark red mottling. On cut surface, similar
mottling is observed and there were numerous microcavities that contained flocculent yellowish-
brown liquid. The chorionic surface of the placenta had a roughly 30-cm x 40-cm, well-demarcated,
pale-pink to yellow area that was surrounded by hyperemic chorion that was variably covered by
thick dark brown mucous. In some areas, the line of demarcation was associated with and focally
obscured by yellowish plaques. The amnion and umbilical cord were grossly unremarkable.
Figure 1: Gross image of the placenta. On the allantoic side of the chorioallantois, adjacent to umbilical cord-associated vasculature, are numerous, variably sized
(up to 9-cm in diameter), ovoid to irregularly shaped, firm nodules with pale to dark red mottling (adenomatous hyperplasia). The amnion and umbilical cord are
grossly unremarkable.
Figure 2: The chorionic surface of the placenta has a roughly 30-cm x 40-cm, well-demarcated, pale-pink to yellow area
that is surrounded by hyperemic chorion that is variably covered by thick dark brown mucous. In some areas, the line of
demarcation is associated with and focally obscured by yellowish plaques.
Figure 3 (left, 2x, H&E): Junction of the villous and avillous chorion. The avillous area is composed of edematous and de-
generate trophoblastic epithelium with few villi that are blunted and fused. Adjacent intact villi are markedly congested.
Figure 4 (right, 100x oil, Gram): Gram positive filamentous branching bacilli.
Figure 5 (left, 20x, H&E): Edematous and degenerate
trophoblastic epithelium with villus edema, necrosis,
mixed inflammatory cell infiltrates and Gram positive
bacteria that include filamentous branching bacilli.
Diagnostics
Histopathologic Examination:
Chorion: There was a focally extensive avillous area that was associated with a surface of trophoblastic
epithelium that was mildly edematous with variably degenerate epithelial cells. Multifocally, and more
prominent at the demarcation with the villous portion of the chorion, was villus edema, variable necrosis
and sloughing, and islands of degenerate trophoblasts that were variably associated with necrotic cellular
material, infiltrating neutrophils, and congested vasculature. Along the periphery of these islands, and
more concentrated within areas of dense necrotic cellular debris, were variable numbers of a mixed
Gram positive bacterial population that consisted of small to medium length bacilli and scattered filamen-
tous branching bacilli. Villi that remained intact were multifocally blunted and fused with stromal infiltra-
tion by lymphocytes, plasma cells, and neutrophils.
Allantoic nodules: The nodules were composed of numerous, variably sized, multifocal to coalescing cyst-
ic glandular structures that were filled with variable amounts of lightly eosinophilic proteinaceous fluid,
necrotic cellular material, degenerate neutrophils, and variably sized dark purple globules. These pseudo-
glands were lined by plump, sometimes vacuolated, cuboidal to squamous epithelial cells that were typi-
cally 1-3 cell layers thick. The glandular structures were surrounded by a mildly edematous and congested
stroma.
Morphologic Diagnoses:
Chorion: Chorionitis, lymphoplasmacytic and neutrophilic, focally extensive, chronic-active with tropho-
blastic degeneration and necrosis and a mixed population of intralesional Gram positive bacilli (including
branching filamentous forms)
Allantoic nodules: Adenomatous hyperplasia, multifocal to coalescing, mild to marked, chronic-active
References
1. Christensen, B.W., et al., Nocardioform placentitis with isolation of Amycolatopsis spp in a Florida-bred mare. JAVMA, 2006. 228(8): p. 1234-1239.
2. Donahue, J. and N. Williams, Emergent causes of placentitis and abortion. Vet Clin North Am Equine Pract, 2000. 16: p. 443-456.
3. Labeda, D., J. Donahue, and N. Williams, Amycolatopsis kentuckyensis sp. nov., Amycolatopsis lexingtonensis sp. nov. and Amycolatopsis pretoriensis sp. nov.,
isolated from equine placentas. Int J Syst Evol Microbiol, 2003. 53: p. 1601-1605.
4. Donahue, J., N. Williams, and S. Sells, Crossiella equi sp. nov., isolated from equine placentas. Int J Syst Evol Microbiol, 2002. 52(2169-2173).