Hello and welcome to the forum. I understand that Tails use different products so without knowing the type that your dogs had it is not possible to say which ingredient/s were problematic.
The first rule when looking for a suitable food is to look at the ingredient list - it should be crystal clear so you know exactly what you are giving your dog. Secondly, but just as important the meat source should appear at the top of the list and be named. If you see the word 'derivatives' in the list, it is not a good sign. All this (and more) is explained and discussed in this thread.
We can help to source a better product for your dog using the Dog Food Directory. However, to use the filters we need more information. For instance, type - dry/wet/raw/fresh, budget, preference for buying - online/pet shop/supermarket.