I switched my dog to a better quality food but didn't have any of the old food left to transition her slowly?

At most a little digestive upset, (loose stools) doesn't last long.

I wouldn't worry about not transitioning her food. She might vomit once or twice but nothing serious should come of it. Check the bag and see if it has wheat. A vet told me once that many dogs are allergic to wheat. A very common allergic reaction in dogs is itchy feet. If your dog spends a lot of time chewing the bottoms of it's feet it's probably a reaction to something like it's food or even some plants outside that are bothering it. How often do you give your dog baths? Dogs have very sensitive skin and if you bath them too often it can cause problems especially if you don't get them dry all the way to the skin. Also dogs skin can get dry just like peoples. A good cure for that is adding a good oil such as fish oil to their food daily. The vet should have some good supplements and so should pet shops. I don't know if Frontline kills mange but your dog could have mange which is a mite that burrows into the skin and causes a lot of itching. If that's the case you will be wise to get the help of a veterinarian. Stress (yelling,loud noise, abuse, other dog being dominating, boredom, lack of exercise) can cause a dog to itch. She might even be allergic to something in the Frontline. Good luck in figuring it out. I have had several itchy dogs and know how elusive the remedy can be. The quickest, easiest solution is to just go to the vet if you can afford it. That will save your dog a lot of misery.

Maybe nothing will happen and maybe she'll end up with explosive diarrhea, since all dogs are different. If it were me, I would have just bought another 20 lb. bag of the old and do the gradual thing. This way you would be doing the right thing, and you also won't have to go shopping for dog food for awhile or end up with your dog having the sh*ts. When I acquired a *second hand dog* about a year ago, she had some MAJOR GI problems, and we found out she couldn't tolerate grains. When switching to a grain free food, we still did the gradual change as I didn't want to make things worse for her before making them better, nor have to clean up the messes in house, which were not her fault to begin with.

Some dogs are absolutely fine with abrupt changes in diet, so you may not have any problems.

But if your dog turns out to be one who is senstive to abrupt changes in food, then you may see vomiting, gas and loose stools.

If these two foods have "basically the same ingredients", how is a change meant to improve her skin problem? Has the dog been to a vet about the skin issue?

She might have some runny stool for a bit but that is about it.

If she has a skin allergy going on and no issues with fleas I would stop using the frontline for a while also.

It will take about a month or so to see a difference if it was her food.