Effects of castration on penile extracellular matrix morphology in domestic cats.

Objectives This study was undertaken to verify the possible modifications caused by hormonal deprivation in the extracellular matrix in the penises of neutered cats. Methods Twenty-seven penises from domestic shorthair cats were collected: 14 samples from intact cats and 13 from neutered cats. Sections were stained with Weigert's resorcin-fuchsin, hematoxylin and eosin, and picrosirius red. Histomorphometric analysis was performed using light microscopy and image analysis software. The following parameters were analyzed: density of the elastic fibers and collagen fibers in the corpus spongiosum; density of the elastic fibers in the tunica albuginea of the corpus cavernosum and the tunica albuginea of the corpus spongiosum; luminal area of the urethra; area of the corpus spongiosum; area of the corpus cavernosum; and thickness of the urethral epithelium. The data were analyzed using the Shapiro-Wilk test to verify the normal distribution, and groups were compared using Student's t-test; P <0.05 indicated statistically significant differences. Results Significant differences were observed between intact cats and neutered cats in the density of elastic fibers in the tunica albuginea of the corpus cavernosum (8.13% ± 1.38% vs 3.11% ± 0.66%), tunica albuginea of the corpus spongiosum (4.37% ± 1.08% vs 3.30% ± 1.01%) and corpus spongiosum (6.28% ± 3.03% vs 4.10% ± 2.19%), and density of collagen fibers in the corpus spongiosum (34.11% ± 10.86% vs 44.21% ± 12.72%). Conclusions and relevance The results show a significant decrease in the density of the elastic fibers and a significant increase of the density of the collagen fibers in the corpus spongiosum in neutered animals. This suggests that the compliance of the periurethral region is reduced, and these changes could be a predisposing factor for urethral obstructive disease.