feeding canned and/or dry

I have 17 cats which are rescue kitties, so while most love me and some just don't mind me, a few don't care for people at all.
They are all in door cats and their area, in addition to the house, includes a large screened porch where they spend most of their time. There food, water and litter boxes are located on the porch. Most of my cats look healthy and are active and playful, but I have two (sisters) who have some digestive problems (diarrhea). They use their boxes, but don't always make it in time. They are also thin. I managed to get one in a carrier- probably about a year ago now- and the vet ended up telling me that it is their food. I know, just like people, one animal can have a sensitivity while another doesn't. I have been feeding Friskies canned and dry food, but am concerned about quality. I recently purchased "Chicken Soup for the Cat Lover's Soul" and haven't seen much of change, if any. It has only been about a week and a half.
Would it be better to give then this type of dry food and no canned food, or do you think the canned grocery store food would be better than no wet food? Unfortunately, cost is a factor.
Thank you for your advice.

RESPONSE:

It sounds like your cats may have a food sensitivity since your vet didn't find anything. Canned or dry only is unlikely to make any difference, it is the quality of the food that matters. Raw meat diets work very well to control this. If that is not an option, and you cannot get good high quality cat foods because of the costs, you may want to try some probiotics or all natural therapies to help control the loose stools.
Only Natural Pet has some really good products and we have used them often for chronic issues in our cats. Check them out and see if there is something that works for your babies. Whether food changes or holistic therapies, you should start to see some improvement within a few days. Be sure to transition to new foods over several days to minimize digestive upset. Once they are on the new food exclusively, if you don't see improvement within a week or so, it is safe to assume that it is not making a difference. Unfortunately, with digestive issues that have no cause, trial and error is the only way to find out what will help. Let us know how it goes.

Donna - House Full Cats Mom