Allergies and other sensitivities can develop through exposure, so as your cat ages, she may no longer tolerate dyes and food additives that did not bother her when she was younger.
In other words, even if she has eaten a particular food for years with no problems, there may come a time when she can no longer eat that food. If you notice changes in your cat's skin and coat, elimination patterns, or behavior, or if she develops bad breath or gains or loses weight, talk to your vet and keep in mind that many health problems are food related.
High quality foods do cost a bit more per bag or can because they contain better ingredients. On the other hand, they are nutritionally denser and are more easily digested that poorer foods, so your cat can eat less food per meal and get better nutrition.
The cost per meal may be about the same, and the health benefits of better food are incalculable. Price alone does not indicate high quality, of course. Some of the more expensive cat foods offer more in advertisement that tug at your heart than they offer in food quality.
I would suggest that you spend some time reading labels in a pet supply store and perusing some of the websites recommended so that you can make an informed decision about the best food for your aging cat.
High quality cat foods are recommended for seniors because they are nutritionally denser and more easily digested than poorer foods. So, how to change your senior cat's food? Age often makes the digestive system more intolerant of change.
And, a sudden switch to a new food may cause vomiting and/or diarrhea. If you need to change your senior's cat food, make the change gradually, slowly increasing the proportion of new food and decreasing the old over the course of a week or two.
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