Gestational period and reproductive cycle in Spix's yellow-toothed cavy (Galea spixii Wagler, 1831)

Abstract

Spix's yellow-toothed cavies are rodents displaying high biological and farming potential. Knowledge of cavy reproductive aspects is paramount for satisfactory breeding. This study aimed to determine the gestation length and characterize the reproductive cycle phases of Spix's yellow-toothed cavies, also investigating potential male effects on these processes. The investigated animals were categorized into three groups: Gestational follow-up (G1), with a 5:1 female-to-male enclosure ratio; estrous cycle (G2), with a 5:1 female-to-male ratio with a male confined to a cage; and G3, consisting of five females and no male. Daily colpocytological examinations were performed, with the presence of spermatozoa on the microscopy slides indicative of copulation. G1 females were separated from the male immediately after copulation, with this being considered day "zero" of the pregnancy. G2 and G3 females were evaluated for two complete estrous cycles and qualitatively assessed through vaginal smears. The gestation length of the Spix's yellow-toothed cavies averaged 59 ± 2.24 days, with a continuous polyestrous cycle lasting 14.8 ± 0.73 days in G2 and 14.6 ± 0.75 days in G3. The proestrus phase was characterized by the dominance of parabasal cells, dyes, bacteria, and leukocytes; the estrus phase, by superficial cells with the predominance of anucleate cells with and without the presence of bacteria; the metestrus phase, by parabasal cells and numerous genuine cells, neutrophils, and bacteria; and the diestrus phase, mainly by basal, parabasal, and mutant cells, as well as high amounts of vaginal mucus, neutrophils, and bacteria. The presence of a male cavy significantly influenced diestrus duration, prolonging this phase, which is potentially attributed to female progesterone production effects.
Keywords: Estrous cycle; estrus; Galea spixii; pregnancy; rodent.