Testicular ultrasound analysis is a non-invasive diagnostic method and an important step in andrological examination, which enables the early assessment of fertility disorders. Given the importance that asinines have for low-income families, and the need for experiments to establish these patterns of andrological evaluation for donkeys, this study aims to quantitatively determine the testicular echogenicity without a defined racial pattern, as well as to evaluate the testicular biometry and ultrasound changes observed in the testicles of these animals. 30 asinines without a defined racial pattern were used, divided into two groups according to age group (AG1 - 15 animals from 16 to 50 months of age and AG2 - 15 animals over 50 months of age and maximum 130 months). Ultrasound scanning was performed in longitudinal and transverse sections of the testicles. The images obtained were analyzed using GIMP 2.8 software (2012) and a standard gray scale graph (histogram) was generated. The AG2 group showed a significant difference in testicular length, width, and height (P < 0.05), when compared to the AG1 group. When comparing the volume and testicular index between the groups, it was observed that the animals of the AG2 group presented values higher than that of AG1 (P < 0.05). There was no significant difference (P > 0.05) between echogenicity (gray scale histogram) of the parenchyma and left testicular mediastinum, between the studied age groups. There was a significant difference (P < 0.05) between the echogenicity of the mediastinum of the right testicle between the age groups.

Keywords: Diagnostic imaging, reproduction, ultrasound, asinines