I believe the problem is what you are feeding and you are feeding dry foods. You need a canned food with no grains.
Nutrition since there are so many bad things out there is very important to your cats health
Contrary to what you may have heard; dry foods are not a great thing to feed a cat.
Please read the label on what you are feeding? What are the ingredients? Do you know what they mean? Is the first ingrediant a muscle meat like chicken or meal or other things?
Dry foods are the number 1 cause of diabetes in cats as well as being a huge contributing factor to kidney disease, obesity, crystals, u.t.is and a host of other problems. Food allergies are very common when feeding dry foods. Rashes, scabs behind the tail and on the chin are all symptoms
The problems associated with Dry food is that they are loaded with grains and carbohydrates which many cats (carnivores) cannot process. Also, Most of the moisture a cat needs is suppose to be in the food but in
Dry, 95% of it is zapped out of dry foods in the processing. Another thing, most use horrible ingredients and don't use a muscle meat as the primary ingredient and use vegetable based protein versus animal. Not good for an animal that has to eat meat to survive.
You want to pick a canned food w/o gravy (gravy=carbs) that uses a muscle meat as the first ingredient and doesn't have corn at least in the first 3 ingredients if at all. The best food for cats does not contain any grains at all.
Fancy feast is a middle grade food with 9lives, friskies whiskas lower grade canned and wellness and merrick upper grade human quality foods. I would rather feed a middle grade canned food then the top of the line dry food.
Also, dry food is not proven to be better for teeth. Does a hard pretzel clean your teeth or do pieces of it get stuck? http://www.felinefuture.com/nutrition/bpo_ch4a.php
Please read about cat nutrition.
Vetinarian diets The reason your vet thinks so highly of the pet food they sell probably has more to do with money than nutrition. In vet school, the only classes offered on nutrition usually last a few weeks, and are taught by representatives from the pet food companies. Vet students may also receive free food for their own dogs and cats at home. They could get an Iams notebook, a Purina purse and some free pizza. http://iml.jou.ufl.edu/projects/Spring04/Perhach/PetFood/Vets.htm