Reproductive parameters of male crab-eating foxes (Cerdocyon thous) subjected to pharmacological semen collection by urethral catheterization

Abstract

The crab-eating fox inhabits all Brazilian biomes, but little is known about its in situ reproduction. The objective of this study was to assess the pharmacological semen collection by urethral catheterization in crab-eating foxes. In addition, we compare seminal and reproductive biometric parameters between juveniles and adults, as well as between the breeding season (June to September) and the non-breeding season (October to May). For this study, free-living crab-eating foxes (individuals n = 8; adult = 6 and juvenile = 2; capture events N = 10) were captured in the Pantanal using Tomahawk traps. Biometric parameters, such as testis volume, differed between juveniles and adults, but there was no difference when comparing adults across seasons. All eight attempts to collect semen from adults were successful, but attempts to collect from juveniles were unsuccessful. The average semen volume (±SD) was 39.13 ± 21.98 µL, with motility averaging 40 ± 29.01 % and vigor of 2.57 ± 0.79. The sperm concentration was 277.57 ± 298.74 × 106 sperm/mL, and the percentage of morphologically normal sperm was 50.1 ± 14.7 on average. Significant increases were observed in sperm motility, concentration, and the proportion of sperm with normal morphology during the breeding season. It is the first time that pharmacological collection has been performed on the species and the first time that semen has been collected from free-living C. thous. The results suggest that male crab-eating foxes exhibit temporal variation in seminal quality, providing additional evidence that this species is a seasonal breeder.