Seasonal changes in steroid hormone profiles, body weight, semen quality, and the reproductive tract in captive African wild dogs (Lycaon pictus) in South Africa

Abstract

Characterization of reproductive seasonality in the African wild dog (Lycaon pictus) could assist reintroduction programs. Male wild dogs (n=14) were assessed quarterly (January, mid-summer; April, late summer; August, late winter; November, early summer) for serum testosterone, body weight, testicular and prostatic volume, preputial gland measurement, and ejaculate characteristics. Bi-monthly fecal samples were collected from male (n=11) and female (n=4) wild dogs for analysis of fecal androgens and progestagens. Fecal androgens were higher in early summer (246.4±14.5ng/g) than in early winter (218.6±13.4ng/g). Serum testosterone was higher in mid-summer (1.4±0.3ng/ml) than in late winter (0.7±0.1ng/ml). Number of spermatozoa per ejaculate was greatest in late summer (301.4±39.3×106). Other semen parameters peaked in mid-summer (pH: 7.4; progressive motility: 85.0±0.1%; live spermatozoa: 81.0±16%; normal morphology: 71.5±8.2%). Total testicular and prostatic volume were greater during summer (testicular: 36.7±4.2cm3; prostatic: 12.0±1.9cm3) than winter (testicular: 25.2±1.9cm3; prostatic: 5.8±0.8cm3). Preputial pendulance also was greater in summer (7.1±0.5cm; n=9) than winter (5.9±0.2cm). Baseline fecal progestagen metabolites were 6.2±2.5μg/g and peak fecal progestagen metabolites were 14.7±2.8μg/g. Copulations resulting in pregnancies (n=2) occurred in late summer and gestation was 71days. Female wild dogs were seasonally monoestrous with mating in summer and winter. In conclusion, wild dogs are reproductively seasonal with improvement in male reproductive variables during summer and a bi-phasic seasonal pattern to female receptivity.