2018: TRANSCUTANEOUS ULTRASOUND-GUIDED TWIN REDUCTION IN A QUARTER HORSE MARE


 

Transcutaneous ultrasound-guided twin reduction in a Quarter Horse mare 

College of Veterinary Medicine, Texas A&M University, College Station, TX 
  

Twin pregnancies maintained through late gestation are undesirable due to complications 
such as abortion, dystocia and may prove fatal to the mare,1 as well as complicate the resumption 
of a normal estrous cycle and rebreeding of the mare.2 Current options for treatment of a twin 
pregnancy include manual reduction per rectum, cranio-cervical dislocation, transvaginal 
ultrasound-guided, or transcutaneous ultrasound-guided twin reduction.2 A healthy, 9-year-old 
Quarter Horse mare was referred to the Texas College of Veterinary Medicine for transcutaneous 
ultrasound-guided twin reduction. Abdominal ultrasonography identified two fetuses in the right 
ventral abdomen, both with normal tone and heart rate. The larger fetus (thoracic diameter 7-8 
cm) was present in the right cranioventral abdomen, while the smaller fetus (thoracic diameter 6-
7 cm) was present in the right inguinal region. The mare was sedated and the right caudoventral 
abdomen was clipped, aseptically prepared, and a local anesthetic (carbocaine) was applied. 
Using ultrasound guidance, an 18g 3.5” spinal needle was inserted into the heart of the smaller 
fetus and 6 million units (15-20 mLs) of procaine penicillin G (PPG) was injected to induce 
cardiac arrest. The larger fetus maintained a normal heart rate (93 bpm), tone, and rhythm 
throughout the procedure. Postoperatively the mare was treated with flunixin meglamine, PPG, 
and altrenogest and recovered normally. Abdominal ultrasonography later verified the presence of 
the larger fetus with a normal heart rate (131 bpm) and tone, and the smaller fetus, which had no 
heartbeat and decreased tone. The mare delivered a viable-term foal in addition to the mummified 
remains of the non-viable fetus without complications. This case highlights a common 
reproductive problem in the mare and is an example of the optimum outcome of a transcutaneous, 
ultrasound-guided twin reduction procedure. 

 
Keywords: Mare, twin, pregnancy, reduction, transcutaneous, ultrasound-guided 

References 
1. Miller A, Woods GL: Diagnosis and correction of twin pregnancy in the mare. Vet Clin North Am Equine 

Pract 1988;4:215-220. 
2. Tan DKS, Krekeler N: Success rates of various techniques for reduction of twin pregnancy in mares. J Am 

Vet Med Assoc 2014;245:70-78.  
 

Clinical Theriogenology • Volume 10,  Number 3 • September 2018 350

S.R. Grissom, C. Navas De Solis, A.M. Ripley, C.C. Love