Clinically, collagen fleece patching of the penile tunica albuginea (TA) has been successful. However, the histopathological and hemodynamic outcomes are not known. We studied in vivo TachoSil® patching in two beagle dogs weighing 16.8 (16.7-16.9) Kg. Bilateral intracavernous pressures (ICP) response to 10 mg papaverine hydrochloride were measured. A full-thickness defect was created on the left side in TA 1 × 0.5 cm, and four transverse incisions 1 cm long were made on the right side, placed 0.5 cm apart, and covered with TachoSil®. Six months later, ICP measurements were repeated, and the penis was excised for histopathology. Grossly, the graft site was indistinguishable. The mean baseline ICP was 19.3 ± 2.98 mmHg and increased after papaverine injection to a mean peak ICP of 122 ± 26.1 mmHg. The ICP measurement before and after grafting did not show a significant difference in the baseline (p = 0.068) or the peak pressure (p = 0.465). Histologically, minimal foreign body reaction was seen, and the TA was completely regenerated. The underlying cavernous tissue did not show inflammation or necrosis. The study is the first to show the long-term histopathologic regeneration of TA after collagen fleece patching while maintaining the hemodynamic response to papaverine.