Survey of Testicular Lesions in Stallions

Abstract

Very little is known or has been published about the incidence of testicular lesions in the general equine population. The aim of this survey was to assess the incidence of microscopic lesions in a random sample of pubertal stallions of different ages. Testicular tissue from 65 adult stallions were fixed, processed and stained for microscopic evaluation. A board-certified pathologist evaluated the histological slides and assigned grades to the tissue based on distribution and severity of any present lesions. Tissue alterations were grouped by their location in seminiferous tubules, testicular interstitium, rete testis, epididymis or capsule. In the seminiferous tubules, 89% of the sampled stallions had evidence of tubular degeneration and 31% had evidence of tubular atrophy. Tubular dilation, intraepithelial cysts and intratubular giant syncytial cells characterized the degenerated seminiferous tubules. Intratubular granulomatous inflammation was present in 38% of the stallions. A malignant seminoma was identified in one stallion. Of the 65 stallions, 92% had significant tissue alterations presenting as interstitial edema, Leydig cell hypocellularity, perivascular lymphocytic inflammation and interstitial fibrosis. The majority of the lesions graded as minimal to mild; some were moderate or severe. No significant tissue alterations existed in the rete testis, epididymis or capsule.