by Pierce Fleming, DVM
April 20, 2013
Most people and even some veterinarians tend to treat cats as small dogs. In many instances this distinction is valid. However, in regards to nutrition, the two species have very different requirements. Dogs (and humans) are omnivores. That means they are efficiently able to utilize animal and vegetable protein. Cats are true carnivores. They need the nutrients of animal tissues. Their digestive systems are not equipped to process carbohydrates as efficiently as dogs and people. And dry food, kibble specifically, is necessarily formulated with starch and plant based ingredients. Cats inability to metabolize carbohydrates efficiently can lead to obesity and it’s many health problems.
Cats metabolically are designed to use higher levels of protein and fats for energy than omnivores. Their metabolism is limited in it’s ability to lower the glucose loads post eating so instead of being used for or stored as muscle energy, it is stored as fat. High amounts of dietary carbohydrates increase this glucose load and actually decrease cats ability to digest protein as well.
Cats need higher amounts of specific amino acids that are essential to their proper nutrition. They are unable to synthesize these as omnivores can because they are a part of a natural carnivorous animal protein diet. They also require increased amounts of many water soluble B vitamins as well as fat soluble vitamins, some of which are found naturally only in animal tissues.
A 2011 study by the Association for Pet Obesity Prevention found that over 50% of cats were either overweight or obese. Wikipedia defines obesity as a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. House cats fed energy dense, high-starch, dry foods take in more caloric energy then they need and this gets stored as fat. Most cats are relatively inactive which contributes to their propensity to put weight on. And the more weight they put on, the less active they become spiraling into a circle of health problems.
Overweight cats, as with overweight people, are prone to diabetes mellitus. But most cats develop non-insulin dependent diabetes as opposed to omnivores that usually develop the insulin-dependent form. This is important as to how the diabetes is controlled because non-insulin dependent diabetes can often be controlled through diet. Obesity in cats causes resistance to the effects of insulin. Diet recommendations for insulin-dependent diabetes in omnivores include low fat, high fiber diets. But because of the unique metabolism of cats, high protein, low carbohydrate diets will result in weight loss that will reduce their insulin resistance. This lowers the amount of insulin required for cats and up to one third of these feline diabetics can actually get off insulin altogether. Not surprisingly, there is a prescription diet for that (and it even comes in a convenient dry form!).
Cats eating commercial dry food will take in about half the water of cats fed canned food. Of all the recommendations for cats having urinary problems such as chronic infections and crystals in the urine, increasing water intake and keeping proper hydration is perhaps the most important. How many urinary issues would be avoided on a canned food diet alone?
There are many more health problems associated with overweight cats such as fatty liver disease, arthritis, and heart problems. We do not have a complete understanding of the complexities of inflammatory bowel disease in cats but feeding an omnivore’s diet to a digestive system designed for a carnivore may likely play a role in that pathophysiology as well. Sick, injured or anorexic cats have even higher protein needs than healthy cats.
A landmark paper that was written over ten years ago (link below), pointed out these distinctions, but still the veterinary community has been slow to recommend an all or even mostly meat diet for cats. Owners still mostly prefer the convenience of dry cat food to that of canned or raw. We often hear of fat cats who will not even eat anything that is not kibble. Food manufacturers add flavor enhancers to their dry foods that appeal to cats. I won’t even go into heavily processed food such as the semi-moist, spongy cats foods that can also contain sugar derivatives among other processed ingredients. Yes, they do supplement these foods to provide synthesized amino acids and vitamins necessary for proper feline health. But suffice it to say there is enough information available today that explains the health benefits of real food versus processed food, for humans as well as animals. Read some Michael Pollan if you need convincing. But you still need to read your labels! There are lot of canned cat foods that also contain more vegetables and grains then carnivores should have.
As we are learning more all the time as to what constitutes a good diet for ourselves, we, as guardians, need to consider our animals diet as well. Cat owners, in particular, need to be sure they are providing proper nutrition in the form of meat-based diet, be it canned, raw or homemade. You may have to do that gradually to gain your cat’s acceptance of what constitutes a proper diet. But think of it as tough love. Just as you wouldn’t let your child eat a junk food diet, do the same for your kitties. They will live longer, healthier, more active lives. And I’m guessing you will spend a lot less on veterinary bills as well.
Zoran, DL. The carnivore connection to nutrition in cats. JAVMA 2002; 221:1559-1567.
Find that at website: //my.vetmatrix.com/0024270/storage/app/media/DrZoran.pdf
Dr Fleming works at Plymouth Heights Pet Hospital in New Hope, MN