10 Reasons Why Dry Food Is Bad for Cats & Dogs

CatdryfoodUpdated 5/17/20.


In this article, I’ll give you 10 reasons why dry food is so very bad for pets so you’ll understand why, if you want optimal health and long life for your pet, dry food isn’t going to get you there.

1. Ingredients



  • Restaurant waste and out-of-date supermarket meats




Cost isn’t a reliable indicator of quality, although extremely cheap foods are bound to contain extremely cheap ingredients. The manufacturer has to buy ingredients, process them, bag and ship the finished food to a distributor, and at the same time pay for labor and overhead. Then the distributor stores the food and ultimately delivers the food to retail outlets. Those stores charge for shelf space to keep themselves in business. And yet, the food may sell for $1.50 a pound, while guaranteeing a profit for everyone along the way! The cost of all the ingredients in a $1.50/pound food can’t be more than 30 cents/pound. And if the manufacturer also promotes the food through expensive advertising, that cost has to be deducted, too.


2. Processing


While heat processing makes vegetables, fruits, and grains more digestible, it has the opposite effect on proteins. Not only are cooked proteins less digestible, but they become distorted, or “denatured,” by heating. These abnormal proteins may be a factor in the development of food allergies, as the immune system reacts to these unfamiliar and unnatural shapes.


3. Carbohydrates

Carbohydrates are molecules that contain carbon (C), hydrogen (H), and oxygen (O) —carbon and water (H2O) —in other words, “hydrated carbon.” The simplest carbohydrate is sugar; and all carbs are varying configurations of sugars. Fiber is a special type of carbohydrate made by plant cells to keep their cell walls rigid, allowing plants to grow upright from a relatively small base. It takes a special enzyme (cellulase) to digest fiber that dogs and cats do not have.

Dogs and cats are carnivores, meat-eaters. Their natural diet is high protein and high moisture. For example, a whole rat contains about 8% carbs. Natural prey (birds, rabbits, rodents, etc.) contain from 9-10% carbs. Most of this consists of glycogen, the storage form of sugar that the body stores in the muscles and liver; and some comes from undigested food in the prey’s gut. The carnivore’s ideal diet is essentially the Atkins diet: lots of protein and fat, and a small amount of complex carbohydrates from vegetables.

The average carb content of dry cat food is about 30% carbohydrates; but it ranges from 8% in EVO Cat and Kitten food (the carbs are replaced by 44% protein and an astronomical 47% fat), to 48% in Blue Buffalo Lite. Protein is the most expensive ingredient, and carbs the cheapest; so in general (but clearly not always!), cheaper foods contain more carbs.

While classified as carnivores, dogs (and humans) are, in practice, omnivorous, meaning they can use pretty much any food as fuel. They use carbs directly for energy by breaking them down to simple sugars. Sugars not needed for immediate energy, or to replenish glycogen stores in the liver and muscles, are turned into fat. This takes place through several biochemical pathways; but a major pathway used by most mammals (involving the enzyme glucokinase) is essentially absent in the cat. Strictly carnivorous cats preferentially use protein and fat for energy, and these pathways are mandatory. Felines can digest and absorb carbohydrates, but those carbs mostly turn quickly and directly into fat.


Heat processing increases the glycemic index of carbohydrates. Corn—a common ingredient of dry food—has a glycemic index similar to a chocolate bar. When dry food is available all the time, cats in particular will nibble at it 15-20 times a day. This causes multiple sharp swings in blood sugar and requires the pancreas to secrete insulin each time. Over-secretion of insulin causes cells to down-regulate and become resistant to insulin. This is one reason why dry food is a major contributor to feline (Type II) diabetes. While dry food does not directly cause diabetes in dogs, it does contribute to metabolic syndrome, a pre-diabetic condition.

The pancreas also secretes bicarbonate to neutralize the acid in food coming from the stomach. Continual pancreatic stimulation also creates an alkaline environment in which urinary crystals and stones can easily form.

4. Calories

It’s currently estimated that more than 50% of dogs and cats in the U.S. are overweight, and many are seriously obese. Carrying extra weight isn’t cute or cuddly—it will shorten your pet’s life, create unnecessary discomfort, and will surely lead to one or more chronic diseases, such as diabetes, bladder and kidney disease, arthritis, liver failure, chronic gastrointestinal problems, poor immunity, and even cancer. You’re not doing your pet any favors by giving in to those big eyes, and those even bigger appetites, which are in most cases caused and perpetuated by dry food.


  • Diabetes
  • Vomiting
  • Chronic Vomiting
  • Chronic Diarrhea
  • High Blood Pressure
  • Skin and Coat Problems
  • Hepatic Lipidosis (Liver Failure)
  • Pancreatitis
  • Arthritis
  • Heart Disease
  • Asthma
  • Allergic Skin Disease
  • Inflammatory Bowel Disease
  • Bladder Disease
  • Kidney Disease

5. Dehydration

Obviously, dry food is dry. This is a very big problem for cats, whose ancestors are desert-dwelling wild cats. They have passed on their super-efficient kidneys, which are designed to extract every last drop of moisture from prey animals. As a result, cats have a low thirst drive, and don’t drink water until they are about 3% dehydrated—a dehydration level so serious that most veterinarians would consider giving intravenous fluids. Dogs have a higher thirst drive and will drink more readily, so they are less prone to serious dehydration.

Dehydration causes or contributes to many serious health issues, including urinary crystals and stones, bladder infections, FLUTD, constipation, and kidney disease.

6. Potential Contaminants



Animals that die on the farm may not be transported to the rendering plant for days after death. These carcasses can be heavily contaminated with bacteria such as Salmonella and E. Coli released from the decomposing digestive tract. Dangerous E. Coli bacteria are estimated to contaminate more than 50% of meat meals.


In addition, flavorings such as “animal digest” that are sprayed onto dry food can easily become contaminated with Salmonella, as numerous recalls and human illnesses have proven. In 2012, Salmonella sent 49 people to the doctor after they simply touched dry pet food.

Drugs. Because sick or dead animals are frequently processed for pet foods, the drugs that were used to treat or euthanize them may still be present in their meat and organs. Penicillin and pentobarbital (the euthanasia drug) are just two of the drugs that can pass through processing unchanged. Antibiotics used in livestock production also contribute to antibiotic resistance in pets and people.


Chemical Residues. Pesticides, herbicides, and fertilizers may leave residue on plant products. Grains that are condemned for human consumption by the USDA due to residue may legally be used in pet food. The USDA does not even test for glyphosate, the active ingredient in Monsanto’s Roundup®, so there may be any amount of it in either human or pet food!

GMOs. Genetically modified plant products are also of concern. As of 2015, 95% of the planted area of soybeans, 88% of cotton, and 95% of corn in the U.S. were genetically modified varieties. Corn in particular is heavily contaminated with glyphosate. Cottonseed meal is a common ingredient of cattle feed, as are soy and corn. Soy and corn are also used directly in many pet foods. A 2010 study found significant damage to the liver and kidneys of rats fed genetically modified corn, as well as an increase in tumors. Unless corn is specified to be organic, it is almost certainly loaded with glyphosate.

Acrylamide and other Maillard Reaction Products (MRPs). These carcinogenic compounds form at cooking temperatures of about 250˚F in foods that combine certain sugars and the amino acid asparagine (found in large amounts in potatoes and cereal grains). It forms during a chemical process called the Maillard Reaction. Most dry pet foods contain cereal grains or starchy vegetables such as potatoes, and they are processed at high temperatures (200–300°F at high pressure during extrusion; baked foods are cooked at well over 500°F). These conditions are perfect for the Maillard reaction. In fact, the Maillard reaction is desirable in the production of pet food because it imparts a palatable taste, even though it reduces the bioavailability of some amino acids, including taurine and lysine. The amount and potential effects of acrylamide and MRPs, many of which are toxic) in pet foods are unknown.

7. Preservatives 



8. Liver Disease




9. Allergies & Asthma




The gut doesn’t take kindly to this reaction, and will start rejecting the food one way or another: vomiting, diarrhea, or both. Cats seem to be especially good at vomiting, and indeed, vomiting is the primary symptom of food allergies, as well as full-blown inflammatory bowel disease.



10. Kidney and Bladder Stones


Cats get a condition called “Feline Lower Urinary Tract Disorder” (commonly referred to as FLUTD, LUTD, or sometimes by the older, outdated term, FUS—feline urologic syndrome) is not a single disease. In fact, it comes in at least three distinct varieties:

  • Cystitis – This term means “inflammation of the bladder.” The majority of LUTD cases (about 2/3) fall into the category of “idiopathic cystitis” (bladder inflammation of unknown cause). This syndrome in cats is very similar to interstitial cystitis in women. It is rare for bacteria to be involved—most are “sterile” inflammations. (Diabetics and elderly cats are more prone to get bacterial infections because their defenses are compromised.)

Dogs also get cystitis, crystals, and stones. However, in dogs, these conditions are far more likely to be caused by bacteria, partly because so many dogs must hold their urine for many hours while their guardians are at work or school. The urinary system’s natural defenses include urine flowing through and washing bacteria out along with it. When urine is held, bacteria have many hours to colonize the bladder and start causing havoc.


What to Do

To give your pet the moisture and protein content that are so necessary for good health, try canned, homemade, or raw food.

Even though canned food is processed, it’s cooked only once (briefly at lower heat), rather than twice at high heat for dry food (once when the animal products are rendered, and again during extrusion). Canned food also tends to have a much higher protein content than dry food.

Homemade food is ideal, if you are following a balanced recipe. [Warning: most “cookbooks” and recipes on the internet are NOT balanced, and can cause serious harm over time.] When you make your pet’s food, you are 100% in control of the quality of the ingredients, and you can add additional supplements depending on your pet’s individual needs, rather than getting a “one size fits all” commercial pet food.


For Dr. Jean’s best-selling ebook “What Cats Should Eat” (including an updated list of Dr. Jean’s recommended brands by name), please visit our Bookstore or Amazon.com. For our canine pals, “Paleo Dog” has information not only on diet, but also lifestyle: holistic health care, vaccination, and much much more!

Also see:

What Cats Should Eat

Homemade vs. Commercial Food for Cats (and Dogs!)

Homemade Diets for Cats and Dogs

Selecting a Good Commercial Pet Food

Switching Foods

The “Dangers” of a Raw Diet

Why Cats Need Canned Food

Do you really know what's in your cat's food?



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