FIRST POTENTIAL CASE OF NOCARDIOFORM PLACENTITIS IN

A MARE FROM ALABAMA SM Shrader1 JC Newton1 RR Wilborn2 1Department of Pathobiology and 2Department 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 trimethoprimsulfamethoxazole 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 HampE) 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 HampE) 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 BW 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)