Pyloric stenosis arises from muscular hypertrophy and is considered to be congenital. According to Secord, it is seen most frequently in Boxer and Boston Terrier puppies.
"Canine Pyloric Stenosis,"
Iowa State University Veterinarian: Vol. 20
, Article 14.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol20/iss2/14