So, until more is known about the results of vaccination with the FIP vaccine, it is difficult for me to get behind it, even on a theoretical basis. There have been expermental studies of it that add to the confusion. Additionally, there are experts in feline diseases who have plenty of second thoughts. Occasionally my dog vomits a viscous liquid which looks kind of frothy and is a clear to yellowish color. I have never noticed any digested food in the goo.
Occasional vomiting can be a difficult case.
There are quite a few dogs, especially younger ones, that will vomit a bit of froth like you describe every so often. With no other problems than this, it is difficult to throw a lot of resources into trying to figure out exactly why this happens. While dietary indiscretion usually is seen by the vet when more serious gastroenteritis results, there is clearly a whole spectrum of ill effects. Vomiting is also possible from neurologic or metabolic disorders. Vomiting can also be a sign of serious disease.