"Glass Balls Mimic Embryonic Development" - Drs. Nie, Johnson, Braden and Wenzel, from the College of Veterinary Medicine at Auburn University are responsible for research presented in a paper at the 2001 American Association of Equine Practitioners meeting in San Diego*. Their research focused on the use of a glass ball inserted into the uterus of a mare in order to suppress estrus.

The following interview with Dr Nie is an excerpt borrowed from dvmnewsmagazine.com* Apr 1, 2003 -
"The size of the ball is important, and a 35-mm diameter ball seems optimal. After adequate preparation, a sterile palpation sleeve is used and the glass ball is passed vaginally through the cervical lumen and into the uterine body. The glass ball can then be manipulated via rectal palpation and moved further into the uterine body.

Correct placement of the ball at the horn-body junction can be easily confirmed with an ultrasound examination. Some practitioners follow placement of the ball with infusion of antibiotic (ticarcillin at 1 gram is recommended by Nie) to help with any possible infection. Correct sterile technique will lessen the need for such use however.

The ball should be placed within 24 hours of ovulation. Some veterinarians have reported that certain mares will spontaneously expel the balls, but this is uncommon and was not observed in any of the mares in Nie's study. The use of glass balls to suppress estrus provides the practitioner with a safe, simple method of keeping some mares out of heat.