A newly developed vaginal probe to detect freemartin heifers and/or determine if heifers born co-twin to a bull have a normal reproductive tract.The crucial probe end length is 7 cm. Research has shown that no freemartin calf has a vaginal length longer than 7 cm.The distal end of the narrower center section is 14 cm from the tip. Over 95 percent of heifers born co-twin to a bull and with a normal reproduction tract have a vaginal length of 14 cm or more. Animals with a vaginal length of 7-14 cm should have chromosome testing done to confirm if a freemartin. This probe is designed to be used on heifers 30 days or less of age. Call toll free 1-800-892-6978 or email us at info@animalhealthusa.com