Age-related diffuse chronic telogen effluvium- type alopecia in female squirrel monkeys (Saimiri boliviensis boliviensis)

We investigated the diffuse alopecia affecting some female squirrel monkeys (Saimiri boliviensis boliviensis) housed in a breeding facility. We randomly selected 100 female and 10 male animals and performed a complete physical exam and a hair assessment on all animals; blood tests, trichograms, hair density; and skin biopsies in representative cases; and a dominance behavioral assessment of 50 animals. Hair coat was normal in 35 female monkeys and all 10 male animals. Of the 65 females with diffuse alopecia, 17 had mild, 22 moderate, and 26 severe hair loss. The alopecia group had a mean age of 9.6 +/- 0.6 years, whereas that of the normal group was 4.7 +/- 0.6 years (P < 0.05). The parity in the alopecia group was 4.2 +/- 0.6 but 2.0 +/- 0.6 (P < 0.05) in the normal group. There were no statistically significant differences in body weight, hemoglobin, blood urea nitrogen, serum glucose, liver aspartate aminotransaminase, or free thyroxine. The trichogram demonstrated 20.8% +/- 1.6% (mean +/- standard error) of telogen hairs in the alopecia group compared with 9.5% +/- 2.8% of the control group (P < 0.05). The hair density in the alopecia group was 52.8 +/- 4.1/cm2 and 79.6 +/- 14.3/cm2 in the control group. Skin biopsies in affected monkeys demonstrated increased telogen follicles, with no fibrosis or inflammation. There were no statistically significant differences in the dominance behavioral analysis. The findings are consistent with chronic telogen effluvium (CTE). A number of organic, behavioral, and dominance-related stress causes of CTE were excluded. CTE appears to be predominantly age-related in this population. CTE in female squirrel monkeys may serve as an animal model for human diffuse alopecia.