RESUMO
The aim of this study was to monitor the oestrous cycle using vaginal cytology, ultrasound and measurement of hormone levels associated with the modification of external genitalia in female Euphractus sexcinctus. Five adult female six-banded armadillos were used for the study. Every three days, we chemically restrained the animals with a combined dose of ketamine and xylazine for 90 days. On each occasion, we conducted vaginal cytology and monitored the alterations in the vulval appearance. In addition, we obtained blood samples for serum estradiol and progesterone analysis and evaluated the ovaries by ultrasonography (8 MHz). As results, at least two entire cycles were monitored per female as based on external oestrous signs. We determined that six-banded armadillos' oestrous cycle lasts 23.5 ± 3.12 days, comprising 8.8 ± 1.4 days for oestrogen phase, in which we verified vaginal bloody discharge, vulvar oedema, presence of mucus and ease of introduction of the swab. During oestrus, females presented an oestrogen peak of 240.66 ± 12.69 pg ml(-1) , on average, with a positive visualization of ovary follicles by ultrasound. The progesterone phase lasts 15.62 ± 2.1 days, characterized by the absence of bloody secretion and difficulty in introducing the swab; there was verification of a progesterone plateau of 10.83 ± 1.86 ng ml(-1) , on average, with identification of corpora lutea in 60% of the ovaries. This is apparently the first description of the six-banded armadillos' oestrous cycle, which proves the efficiency of a multiparametric analysis to monitor it.
