It is hard to image our purring family members as carnivores, but this indeed is what they are. The medical research supports feeding our cats a diet more in tune with this then previously thought.
In the wild our cats would eat prey such as birds, mice, rabbits, etc. These prey would be comprised of proteins, fats, minerals and roughly 70% moisture; with no significant source of carbohydrates.
Therefore feeding a low moisture, high carbohydrate kibble is a far reach from what cats are designed to eat.
The lack of moisture in a kibble diet means it is inadequate in meeting their hydration requirements. Newer feline specialists are now praising a canned/wet food diet, and discouraging a strictly dry/kibble diet.
If your cat is chronically dehydrated, various health issues may arise; this includes but is not limited to:
Constipation: lack of hydration can create dry, hard pellet shaped stools that become difficult to pass
Bladder issues: stones or crystal precipitates can form in a bladder that is not being flushed on a frequent enough basis. This can potentially cause a urinary blockage which is a life threatening emergency situation.
Kidney disease: constant strain on the kidneys to process toxins, proteins, etc without proper hydration can cause permanent damage.
So what should you feed your cat?
Cats should be fed a high moisture (~70%), high protein, low carbohydrate diet.
What about dental health?
Dry kibble has been touted to clean teeth but in reality cats are not effective chewers and most dry food has minimal impact on their dental health.
However there are some functionally designed and tested dental kibble that can be used supplementary or as a treat to help clean the teeth.
Some high protein/low carbohydrate canned food found in pet stores include - Natures Variety Instinct - Wellness Core or Wellness Grain Free - Go!