Have you contacted vet offices and low cost neuter/spay clinics? Since he is intact and someone may be keeping him, the finder may go and have him neutered.
There is a found basenji mix in San Antonio- does anyone know who is missing this pretty girl?
I found this girl (I call her Annie) on October 30 in San Antonio. She is about 24 pounds. She was not wearing a collar when I found her - I put the collar on her and got her vaccinations (the tags in the picture). I am attaching a picture. If you think you might like to adopt this sweet girl let me know…
If there's anyone who can help with adopting her, please contact me and I will give you the finder's email address.