I have a 5 1/2 month old English mastiff puppy. For the past 2 weeks he's had very loose stools. He's been tested for worms and giardia which came back negative. The vet said he may not be getting enough fiber in his diet. I have him on Premium Edge large breed puppy food and the vet gave me Hill's W/D for weigh gain control (adult food). I don't think I can afford both brands of food. Do I continue him on the puppy food and find a fiber supplement or should I switch him to adult food higher in fiber? He currently weights 83lbs. Is he growing too fast. The vet didn't give me any solid answers to go on. I reallly am lost at this point.
Innova and Wellness may be too rich for the OP's puppy. Especially the Innova as it is very high in calories and fat.
If your vet thinks your puppy is overweight then I would heed his advice, especially because you have a large breed. Being overweight during the growth stage is not good for your dog as it puts unnecessary stress on his 'immature' joints. Once his growth plates close, this stress may do serious damage to his physical structure and problems such as hip dysplasia may result.
How long have you fed the Premium Edge food? I would ask your vet what kind of test he used to screen for worms or Giardia. If he used a fecal flotation or a snap test for Giardia, I would ask him to send a stool sample to a labratory for a more definitive test. The snap test can give false negatives and the fecal flotations aren't totally reliable...as I've seen at the clinic where I work.
Also, it sounds like he's still eating. Is he drinking an abnormal amount of water? Is he vomiting? Is he still acting like himself? Or is he lethargic?
One thing you can do is fast him for 24 hours. Then start feeding him boiled chicken with a bit of the broth...just a little at a time. Then once he can eat that, add some white rice. A bland diet may be just what he needs.
You can always add some pumpkin (you can use the canned but not the pie filling) as well to help with the loose stools. But right now, try the bland diet and see if his stools firm up. After you gradually reintroduce his regular food, and the diarrhea resumes, you may want to consider a change in food. Oh yes, and you may want to decrease the amount of food you feed him and increase the amount of exercise he gets. Take him for an extra walk. No treats.
Once his stools and diet are stable, you can give him steamed green beans as treats or puree them and add to his food. You have to process veggies somehow by cooking or pureeing as dogs cannot break down the cellulose. Anyways, green beans are an excellent source of fibre and are low calorie. So decrease his food by 1/4 cup and add green beans.