Impact of fine or large needle aspiration on the dog's testis: in vitro ultrasonographic, bacteriological, gross anatomy and histological assessment

Despite its extensive use for evaluation of spermatogenesis and assisted reproduction, the safety and consequences of fine (FNA) and large needle aspiration (LNA) to the testicular parenchyma and its normal function have not been established. This study was performed in order to accurately assess, by serial in vitro ultrasonographic, bacteriologic, gross anatomic and histological examinations, the type and extent of the effect of FNA or LNA on the dog's testis. Twenty three sexually mature, 1 to 2 years old, healthy laboratory Beagles were randomly assigned to 2 groups: (1) 5 dogs without testicular aspiration (control group) and (2) 18 dogs in which one of their testes was aspirated using a 23 G butterfly needle and the other using a 19 G butterfly needle (experimental group). Two dogs at a time were castrated 10 minutes, 60 minutes, 2, 14, 29, 63, 76, 90 or 180 days post-aspiration. The control group was also castrated 2, 29, 63, 90 or 180 days after the beginning of the experiment. Following castration, in vitro ultrasonographic, gross anatomic, cytological examinations of epididymal sperm, bacteriologic and histological examinations of the testes were performed. Following testicular FNA and LNA bacteriologic, gross anatomic, histologic, epididymal sperm findings and the in vitro ultrasonographic appearance of the testis were normal, except of intratesticular haemorrhage, detected the first days post-aspiration, and degeneration of less than 1.5% of the seminiferous tubules. Within the parameters of this experiment, testicular FNA and LNA have no ill effect on the canine testis and therefore, both FNA and LNA should be considered safe.