Cows can prolapse before or after calving. While both are situations that must be corrected, there are some differences in the type and severity of a prolapse.

Vaginal prolapses will typically occur before calving - usually in the heavily pregnant cow, according to Robert Cope, veterinarian at Salmon, ID. A uterine prolapse can occur directly after the cow calves.

The vaginal prolapse is more common and looks like a pink mass of tissue about the size of a large grapefruit or volleyball. Prolapse of the uterus is a larger, longer mass, more deep red and covered with the "buttons" on which the placenta attached. A veterinarian should be consulted for a uterine prolapse because it can be life threatening.

A common cause of vaginal prolapse is the pressure and weight of a large uterus in late pregnancy, Cope says. Some heavily pregnant cows will strain when passing manure while lying down, or begin straining from the irritation of a mild prolapse. Vaginitis (inflammation of the vagina), estrus, breeding or the presence of the calf's head or feet within the pelvic canal can also cause a cow to strain until the vagina prolapses, Cope says.

Mild prolapses (a bulge the size of an orange or grapefruit) will usually go back in when the cow gets up. But if she starts to prolapse each time she lies down, or if she strains while lying there, the tissues may be forced out farther, to the point they cannot go back in. Then she has a mass of vaginal tissue bulging out, becoming damaged, dirty and possibly infected.


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According to Cope, the vaginal wall is not a sterile environment, so infection is not the primary concern. Instead, he says, "Once these tissues are turned inside out, the returning blood supply from the prolapsed area becomes restricted, making the tissue swell. The longer it is left outside the cow's body, the more swelling occurs, and the harder it becomes to replace. If the cow is near calving, this swelling may make the birth process difficult."

If the prolapse is large (volleyball size), the urinary passage may also have pressure on it and the cow cannot urinate until the prolapsed tissue is pushed back inside. She may strain to urinate (unsuccessfully), aggravating the problem further.

For these reasons, vaginal prolapses should be repaired as soon as possible, even though the condition is not ordinarily life-threatening, Cope adds.

A prolapse can be life threatening, however, if the cow is not treated early. Heidi Smith, veterinarian at Terrebonne, OR, says some cows prolapse in earlier stages of pregnancy. If they are on summer range where they are not being observed daily, the vaginal tissue that is prolapsed and swollen may eventually become infected and make the cow seriously ill.