These no eaters are not unusual and they are a pain.
The usual scenario is they refuse a meal, so you buy a different brand. They eat that enthusiastically, licking the bowl clean. Problem solved.
The next meal they refuse to look at the food, they won't even sniff it, they cower away as if you are trying to poison them.
You buy a new brand...........
Tinned food, kibble, fresh cooked meat & biscuit, raw meat, fish, egg, baby food, all rejected.
Bowl, plate, floor, roll food into a ball and throw it. They have your measure & they are not going to be fooled into eating.
Your vet says " No dog will starve themselves, they will eat eventually" ....These dogs have not read the same veterinary books.
What can you do?.......Try & relax, give them what they will eat, & accept you are going to have a very skinny dog.( Faith lived on nothing but large Bonios for many months)
For owners that are hoping to show their promising puppy, keeping weight on a cavalier determining to starve itself to a size zero is serious. They often feed a certain drug that will give the dog an appetite
Cavaliers......Tommy Tuppence 2000-2012 and a half share of Faith.
Japanese Chins.... Dandy, Benny, Bridgette and Hana.