Flu? dog? wont eat for 5 days..

Pixie my 2 lb chihuahua came down with a 104 fever on Sat am, she was acting fine, brought her to the vet, the vet noticed a heart murmur never heard before, she thought she could have endrocarditis, (had a echo done, she doesnt, she just has a slight mitral valve insuffiecency), on sun her fever went upto 105.5, she has been congested and stuffed up, had blood work and xrays done, all normal... her temp yesetrday ( wed) and today are normal, but she still wont really eat, and is still acting quiet..  She stopped eating sunday and today is thriusday, i am force feeding her and she WILL eat nutrical, but my question is, how long does a dog go w/out eating when they have a flu/cold/upper respitaroy infection? all tests were normal , could there be something else going on? any ideas? i am so so wortried since she is so small and food is sooooooooo important for her! thks!

[Aleda M Cheng, D.V.M., C.V.A]

Your dog may have had Canine Influenza, which is a very serious disease.

Please ask your vet for an appetite stimulant medication, such as Mirtazipine, or a steroids, or other medication.  She should eat whatever she desires until she is totally well.  Try giving her Human baby food meats, small pieces of chicken, beef, fish, cheese, yogurt, etc.

I am glad your dog is eating a little something, but dogs can go without food for a long time without getting hepatic lipidosis (fatty liver disease), that is deadly in other species.  The dog's ancestor the wolf can fast for several days at a time, then gorge, than fast again for several days.