THE SQUIRREL-MONKEY AS AN ANIMAL-MODEL OF PELVIC RELAXATION - AN EVALUATION OF A LARGE BREEDING COLONY

OBJECTIVE: Findings of pelvic relaxation have been reported in up to 5 0% of older adult female squirrel monkeys. To evaluate further the pot ential use of the squirrel monkey as an animal model of pelvic relaxat ion, we objectively observed and described the perineal findings of 16 0 adult females. The aim of this study was to examine the relationship of perineal findings to age and parity, factors thought to predispose women to pelvic relaxation. STUDY DESIGN: The urethra, cervix, and an terior and posterior segments of the vagina were evaluated. The degree of support loss at each site was documented. Genital measurements wer e obtained by previously reported methods. The findings were tested fo r association with elements of obstetric history, age, and subspecies. RESULTS: The females represented three subspecies and ranged from 3 t o 17 years old with parities of 0 to 10. The proportion of females wit h normal support was inversely related to increasing parity and age. A lthough birth weights, frequency of dystocia at term, and requirement for cesarean section did not differ significantly between females with and without evidence of prolapse, animals with multiple sites of prol apse tended to have infants with higher birth weights. Animals without prolapse were significantly younger and less likely to have been deli vered of a term infant (p < 0.001). Subspecies differences unrelated t o age or parity were found for each of the genital measurements. Diffe rences were also found between animals with normal perineal findings a nd those with findings of prolapse. Animals with prolapse had shorter perineal bodies (p < 0.001), greater genital hiatal ratios (p < 0.001) , and wider genital hiatal measurements (p < 0.001). Females with abno rmal pelvic findings were of increased parity (4.0 vs 1.6, p < 0.001) and age (9.4 vs 6.3 years, p < 0.001) compared with those with normal pelvic findings. CONCLUSION: Analysis of genital prolapse in a large p opulation of breeding squirrel monkeys demonstrated an association of loss of pelvic support with age and parity. A tendency for loss of sup port at multiple sites was associated with obstetric complications. Th ese observations support continuing investigation into the nature and cause of spontaneous pelvic relaxation in this species and support the potential use of this nonhuman primate as an animal model.