Hopefully we'll find other articles about this condition.
Read the very short article on site of Medical Center of Palm Harbor, "
Pyloric Stenosis and Pylorospasm."
That author suggested there is quite a difference in outcomes, depending on whether or not the condition is congenital.
Pyloric stenosis is treated by surgery to enlarge the pylorus. If the condition is congenital, the chances for cure are excellent. If it is due to other causes, chances for complete cure are fair.
Another article on site of Embrace Pet Insurance (which also doesn't list yorkie among the typically affected breeds), talks about diagnosis saying,
Diagnosis of the problem can be difficult if the complete closing down of the pylorus is intermittent, but it usually relies on X-rays after barium administration. These “barium studies” often show a thin line of minimal amounts of this contrast material getting through the pylorus into the intestines, thus strongly suggesting the diagnosis of pyloric stenosis.
Endoscopy (using a fiberoptic device to view the area) will assist the diagnosis by visualizing the thickness of the pylorus and by allowing for tissue sampling of the affected area. Fluoroscopy is another technique used to visualize the motion of material as it passes through the area.
Surgery is sometimes required to establish the definitive diagnosis.
Certain blood test findings will also point to the presence of the disease.