Abstract
Placing a sterile glass ball or marble into the uterine lumen is a popular method to suppress unwanted oestrous behaviour in mares. This is in spite of the original report of Nie et al. (2003), which detailed the lack of efficacy of the technique. Recent reports in the literature have described a number of untoward problems associated with the technique. This paper describes two further cases, one involving fragmentation of marbles in the uterine lumen and a second describing the laparoscopic removal of a marble after it had tracked through the endometrium and became pedunculated between the myometrium and serosa. The inefficiency of suppressing oestrus with glass balls, combined with the potential problems their placement may cause, argue strongly that this practice should be considered unethical.
