2018: MIXED GERM CELL TUMOR IN THE PLACENTA OF AN ARABIAN MARE


 

Mixed germ cell tumor in the placenta of an Arabian mare 

College of Veterinary Medicine, Auburn University, Auburn, AL 
 
A 14 year old Arabian mare was confirmed pregnant at 14 days via transrectal ultrasonography. 

The fetal heartbeat was present at 45 days and again at 5 months gestation. At 9 months gestation, the 
mare was presented for thick, clear vaginal discharge. The mare had travelled as a show mare and was 
current on vaccinations. She previously delivered multiple foals with no complications. Upon physical 
examination, the mare was clinically normal. Temperature, heart rate, and respiratory rate were within 
normal limits. The fetus could not be palpated or detected by ultrasonography transrectally. The fetal 
heartbeat was visualized on transabdominal ultrasonography but was not recorded. The allantoic fluid 
contained hyperechoic flecks. Treatment for placentitis was instituted and included trimethoprim 
sulfamethoxazole tablets (9,600/1,920 mg orally twice daily), altrenogest (22 mg orally twice daily), and 
flunixin meglumine (400 mg IV twice daily).2 The vaginal discharge remained unchanged despite 
treatment. Five days after the initial examination, the fetus was aborted. The fetus appeared grossly 
normal for his gestational age. The mare retained the placenta overnight. The following morning, gentle 
traction was required to remove the placenta as a large mass was holding it within the cervix. After 
removal, multiple masses were noted on the placenta. The fetus and placenta were submitted for 
necropsy. The placental masses and additional lesions found in the fetus’ liver were confirmed to be a 
mixed germ cell tumor. Placental germ cell tumors rarely metastasize to the foal. Metastasis occurs by the 
placental germ cell tumor sending cells through the umbilical vein to the fetal liver.1 The mare was treated 
for two days after the abortion with uterine lavages and infusion. She was re-bred to a different stallion 
two months later and delivered a normal foal. This case represents a rare neoplasia as a cause for vaginal 
discharge and abortion. 

 
Keywords: Equine, placenta, tumor, fetus 

References 
1. Bockenstedt MM, Fales-Williams A, Haynes JS: Equine placental mixed germ cell tumor with metastasis to the foal. 

Vet Pathol 2015;52:360-363.  
2. Bailey CS, Macpherson ML, Pozor MA, et al: Treatment efficacy of trimethoprim sulfamethoxazole pentoxifylline and 

altrenogest in experimentally induced equine placentitis. Theriogenology 2010;74:402-412. 

Clinical Theriogenology • Volume 10,  Number 3 • September 2018 358

C. Ikard, A.K. Johnson, K. Varga