dog cant gain weight

Question
QUESTION: Hi, I have a cocker spaniel.  She is about 2 years old.  And to all of my tries, she has been unable to gain weight.  She is a normal height and length.  But all the different types of food I try, it never works.  She will eat, but is unable to gain weight.  She is unable to eat can food due to it upsetting her stomach, and causes loose stools.  What do i do, I am really concerned about her?

ANSWER: Naya, have you taken a stool sample to the vet for analysis?
If not, I'd certainly do that.

And I'd need to know what canned food exactly that you tried with her?  Are you saying her tummy doesn't get upset on dry food?  What dry food are you feeding?  When you tried canned food, did you transition her over slowly or switch abruptly?

I do have some suggestions but need to know the answers to the above questions first.  And what is her weight now?
Delores

---------- FOLLOW-UP ----------

QUESTION: hi, i have taken a stool sample to the vet the last time i took her, which was about 2 weeks ago.  the stool sample came back fine and healthy.
the canned food that i tried with her was the pedigree.  i even tried mixing it with dry food.  but that didn't help.  i thought about trying puppy food with her.  the dry food that i feed her is the Purina healthy morsels food.  she now weighs approximately 16-18 pounds.

Answer
Well, that may well be your answer.  Pedigree and Purina are full of things that are indigestible for dogs.

If you didn't go very slowly switching her over to another food, that would cause loose stool.

The first thing I'd do is change to a better kibble.
I recommend Canidae or Innova EVO.  Go to their websites and find a dealer near you.  Canidae.com or google Innova Dog food.  AvoDerm is also good and now available at PetSmart.

Start with that and add a little plain boiled chicken to it.
Buy some boneless/skinless chicken breasts...simmer till done and cube it up.  Start with only a little...and add more if things go well.

You can cook a lot of chicken, keep some out to use for several days and freeze the rest and take out as you need it
by freezing it in small baggies.

She needs more calories and a higher quality protein than
she's getting (what you're feeding now is by-products - something that is never in a quality dog food)

Even switching to a new kibble should be done slowly until you see there's no reaction.  3/4 of the old kibble and 1/4 new kibble.  Then start adding the chicken.

When that's all accomplished then I'd use the Canidae canned and add just one or two spoonfuls to the kibble and slowly increase.
Delores