The generally accepted belief is that feeding a high protein diet to older cats and dogs may cause kidney disease or make existing kidney disease worse. This thinking originated from rat studies which showed that a lower protein diet slowed kidney disease. The research was highly influential among veterinarians and carried over to opportunistic pet food manufacturers in spite of the lack of research corresponding to cats and dogs. We now know that older dogs and cats need the same level of daily protein as younger animals.
Low protein diets cannot cause or alter the course of kidney disease. Lower protein levels can lead to malnutrition, with a common effect being muscle loss. As humans and animals age, we tend to lose muscle tissue and we suffer from loss of muscle strength. This is why older persons are less steady and lose their balance easily. You can actually see the atrophy in dogs, especially in the hind limbs and along the spine. New studies show that feeding pets a diet with higher protein increases their amount of muscle tissue and thus their ability to maintain better movement and balance.
Part of the confusion is created because a lower protein diet can minimize some of the symptoms of kidney disease. Lower protein decreases the amount of ammonia which their bodies must convert to urea. Urea must pass through the kidneys then out the body. Pets with kidney disease have a harder time ridding their bodies of this urea, so a lower protein diet could possibly lower the amount of urea passing through their system and thus create fewer side effects (loss of appetite, mouth sores). Since kidney disease is fatal, pets in advanced stages of kidney disease may simply need to be kept more comfortable and a low protein diet may be OK. However, for healthy older pets, a high protein diet is essential in maintaining muscle mass and strength, as well as a healthy immune system and good bone density. Don’t let the pet food companies convince you otherwise!
Information taken from an article by Dr. Ken Tudor, published by PetMD, 7/5/12, “Geriatric Dogs Need More Protein”