Canadian beef producers breed their cows in the late summer to encourage calving during late March, April, and May, when the worst winter weather is usually over. A general rule of thumb is that someone needs to check on cows every three hours, especially heifers that are having their first calf, when there are early indications of dystocia (an extra-large calf), when multiple cows are calving at the same time, and during cold, wet weather. Cows need attention if the early stages of delivery last more than six hours, if labor lasts longer than two hours, or if there are signs the calf is in distress, for example, breech or backwards birth, or a swollen tongue.