Dog knot stuck usually occurs due to anatomical defects in the reproductive tract of either male, female or both dogs. (dog-health-guide.org)
It is particularly helpful for radiolucent stones and anatomical defects of the bladder wall. (lbah.com)
The embryos survived long enough to have distinct anatomical defects, including missing lower limbs and digits — and the absence of the entire lower urinary tract and penis. (sciencemag.org)