The squirrel monkey: an animal model of pelvic relaxation

Casual observations of pelvic prolapse have previously been made in adult female squirrel monkeys. We objectively observed and described the pelvic findings of the adult females in our colony to evaluate their potential as an animal model for studies of pelvic relaxation.

Subsets of a group of 28 adult female squirrel monkeys were examined on three separate occasions and photographed to document perineal findings. Four areas of loss of support in the vagina were described, including the urethra, anterior segment, cervix, and posterior segment. The degree of loss of support at each specific site was documented. Also, three measurements were obtained from each animal, including the distance from the base of the clitoris to the posterior edge of the perineal body and the length and width of the introitus. The length of the perineal body was calculated.

Fifty percent of the animals had at least one site of pelvic prolapse at rest or on straining. With straining 50% had urethral prolapse, 21% had anterior segment prolapse, and 11% had posterior segment prolapse. None of the animals had evidence of cervical prolapse. Of the animals with findings of pelvic relaxation, 43% had combined prolapse at two or more sites. Of the measurements obtained, only the width of the introitus was significantly different between the group of normal animals and those found to have pelvic prolapse (p < 0.0005).

On the basis of observations of our colony of squirrel monkeys, a significant number of animals demonstrated findings of pelvic support loss with defects similar to those observed in humans. Although limitations to some techniques of evaluation and surgical intervention exist, the squirrel monkey is an animal model that may provide new opportunities for basic investigation of the pathophysiologic features and the management of pelvic relaxation.