• horse;
  • colic;
  • abortion;
  • endotoxaemia;
  • fasting;
  • clenbuterol


The medical records of pregnant mares over a 3-year period were reviewed. In all cases persistent pain or progressive abdominal distension were the main reason for referral.

The overall survival rate for the 115 mares treated for colic was 73.9% (85 cases). The abortion rate was 20.5% in surgical patients (34 cases), 40% (5 cases) for mares with uterine torsions and 10.8% (46 cases) after medical treatment. The total abortion rate was 16.4%.

Clinical evidence of endotoxaemia was, except for 1 mare, present in all the aborting mares after colic treatment. Anaesthesia did not appear to be a problem because abortion occurred in 5/46 medically treated cases as well as in 9/39 mares treated surgically. Abortion occurred in 3 mares that suffered intraoperative hypoxia, but fasting for >30 h did not seem to cause prolonged hypoglycaemia and subsequent abortion. Clenbuterol hydrochloride was used as a tocolytic agent in 9 mares with uterine displacement, abortus imminens and post-operative uterine torsion and 3 mares aborted during treatment.