Sometimes after a long, hard birth where a cow tries to have a large calf without help and it's in the birth canal too long, or after a hard pull with the pressure of a large calf coming through the pelvis affects the main nerves that control her hind legs. This can also happen in cows that give birth to a normal birth weight calf, particularly if those cows have a smaller-than-normal pelvic area, or heifers that are first-time calvers delivering a normal-sized to a little larger-than-normal calf.

The Gluteal and the Obturator nerves are the ones most affected; the latter more commonly affected than the former. The gluteal nerve is the nerve that controls the muscles to the buttocks. The obturator nerve runs along each side of the pelvic cavity to control the thigh muscles. If this nerve is damaged, the cow cannot pull her hind legs inward and underneath her to stand. Often one leg's more affected than the other, depending on which side she's lying on. Both legs may also be affected, resulting in her unable to get up without some kind of help. If only one leg is affected, she will be able to get up and stand (with a bit of encouragement), and stay up if the weaker leg can be kept from sliding out to the side. The gluteal nerve can also hinder a cow's efforts to get up, however if she does get up, she'll be a bit wobbly when she walks and possibly loose balance.

No matter what nerve is affected, getting the cow up as soon as possible is important, because the sooner she gets up, the quicker she recovers. If she sits for a long period of time, the worse it will be because often paralysis will worsen or get to the point where it is untreatable and you will have to put her down. Things can get especially bad if she's been lying in an awkward position for a while. Knowing the steps on how to get a cow up as soon as possible is very important.

Note: This condition is often referred to by veterinarians as "Obturator Paralysis."[1]