Dogs are used to eating the same types of food day in and day out. (bracpet.com)
The worst thing you can do is feed your cat the same food every day of it's life; this contributes to allergies and digestive issues. (purebredcatrescue.org)
Although cats don't nutritionally need variety (if the food is balanced and «complete»), most will get bored of the same food day in day out. (messybeast.com)