Jutta Sielhorst

1 INTRODUCTION The incidence of twin pregnancies after fixation in the mare has declined over the last few decades due to improved ultrasound image quality, veterinarians routinely performing early pregnancy diagnosis (<16 days post ovulation) by ultrasonography1 and the reduction of any twin embryo by manual crushing before fixation occurs, with success rates of >95%.2-4 However, twins are occasionally missed pre-fixation due to variable growth patterns that occur with asynchronous...