I know the blood flow seems obvious, but lesser known is the fact that phosphodiesterase inhibitors have direct impacts on the nervous system. There's a PDE4 inhibitor that is commonly used in Japan to treat post-stroke inflammation. (Also, caffeine is a weaker, broad spectrum PDE inhibitor.)
"Firstly, PDE5 inhibitors could enhance memory and learning by increasing long-term potentiation mediated by the glutamate NO-cGMP intracellular pathway, as cGMP-activated protein kinase is thought to mediate memory consolidation.
Secondly, as cGMP is a known vasodilator, the cognitive effects of PDE inhibition could be explained by enhanced cerebrovascular function owing to increased delivery of glucose and oxygen to the brain. Finally, improved erections might alleviate performance anxiety and boost self-confidence, with potential benefits to mood, cognition, and general health."
What a pretty guy! That injury sounds terrible for a bird. Does it heal on its own? Or do they need to do some kind of surgical intervention?