Impaired spermatogenesis, tubular wall disruption, altered blood-testis barrier composition and intratubular lymphocytes in an infertile Beagle dog - a putative case of autoimmune orchitis.

Impairment of blood-testis barrier integrity can be observed during inflammation, infection, trauma and experimental autoimmune orchitis, which is inducible in rodents. In the present study, an initially fertile two-year-old Beagle dog was presented with a decline in total sperm number resulting in azoospermia within five months, verified by twice-monthly semen analyses. The dog was clinically healthy with bilateral small testes and showed normal thyroid function. Bacterial cultures of semen were negative and serum biochemical analyses showed no abnormal findings. To determine causes of azoospermia, the dog was castrated. Histological examinations of hematoxylin-eosin stained testicular sections revealed impaired spermatogenesis, seminiferous tubules with spermatogenic arrest or Sertoli-cell-only syndrome as well as focal interstitial and even intratubular lymphocytic infiltrations. Germ cell sloughing, apoptosis and giant cells were also observed in some tubules. Subsequent immunostainings of smooth-muscle-actin, claudin3, claudin11 and connexin43 demonstrated, for the first time, a mechanical and functional disruption of the tubular wall and alterations of blood-testis barrier proteins in these tubules. Presence of claudin3 and claudin11 in canine testis was confirmed using RT-PCR and sequencing and/ or Western-blot analyses. All findings suggested a possible spontaneous autoimmune orchitis to be the underlying cause for the observed azoospermia.