Most cats that visit our Hollywood Pet Hospital today are fed a dehydrated form of combined protein, carbohydrate and fat in various shapes and sizes. Is this the optimum form of nutrition for a cat? It is my opinion that we have moved away from the optimal form of nutrition for our favorite obligate carnivores. The three main problems with feeding dry cat foods are inappropriate forms of protein, too high a carbohydrate content and too little overall water intake.
An obligate carnivore is an animal that must derive its nutrition from meat-based proteins. This is not because it tastes better, but because cats cannot make certain amino acids that can only be found in meat proteins. Meat proteins and plant proteins are not made from the same amino acid subunits; therefore you cannot simply replace meats with plants and call the diets equal, not for cats anyway. People can take the subunits from plant proteins and break them down and rearrange them to make all of the proteins that our particular bodies need which is why we can eat plants or animals or both. Cats, on the other hand, are missing this ability and have to have these amino acids fed directly and certain of them are never found in plants. Many dried cat foods are created from plant proteins that have been cooked and processed in order to make them more digestible for cats, which were not meant to eat them. Then these diets are supplemented with the missing amino acids in order to prevent obvious nutritional deficiencies. While this method of food preparation creates a diet on which a cat can live, it still does not create a diet that produces the best health for our furry friends.
A second issue with dry cat foods is the percentage of carbohydrates that are in dry foods vs. canned foods. Canned cat foods tend to have a much higher protein vs. carbohydrate ratio (on a dry matter basis). On an as fed basis it can appear that the dry foods have a higher protein concentration, but once this food is rehydrated in the body there is a larger volume of carbohydrate consumed when compared to a canned food diet. Cats do not have the same enzymes or digestive pathways as animals that were meant to eat a higher percentage of carbohydrates in their diet. Therefore they turn the carbohydrates they do eat into fat, rather than glucose that can be used by the body. As a result many cats on dry food diet suffer from obesity or diabetes. Canned cat foods tend to have more actual meat ingredients and less inappropriate grains and carbohydrates and this makes canned foods, in general, superior nutritionally than dry food for cats in particular.
A third issue with eating a dehydrated food product daily for an entire lifetime is that our cats are living in a continuous state of dehydration. A cat in the wild that is catching and eating a prey diet is eating an animal that is 70-80% water vs. our domesticated cat eating a dry diet that is approximately 10% water. This is a complete reversal of the water, nutrient ratio. The response of the pet food industry has been to create very imaginative ways of trying to get cats to drink more. The fact is that once a cat feels thirst it is already in a negative water balance. No matter how much they drink, they will just be playing catch up with the amount of water body needs to breakdown, digest, process, and eliminate the nutrient and waste products of the dehydrated diet that they are consuming. Many owners are surprised to learn, when they take their cat to the vet, that it is dehydrated. “She is always drinking or begging for water.” When I hear this statement it is just more evidence of a pet that is missing the water that it needs in the diet. Cats are frequently brought to the veterinarian with some condition of the urinary system that is stressed by continuously trying to eliminate waste and balance the body’s ph and hydration without having enough water do perform all its tasks. Commonly seen conditions include cystitis, kidney disease, stones and crystals in the urine, urinary obstruction and high urine ph. In some pets, which have these conditions over and over again, long-term resolution is achieved when the diet is changed from dry to canned foods.