The Long Cat Food Guide

Everything and more from the Quick Guide, plus documentation.

A Quick Note On Switching Cat Food:

After reading this information, you may decide that Fluffeh needs a different diet from what she's eating right now. That's cool. You should know, however, that some cats can get diarrhea and/or vomit from abrupt food switches. Go slow, especially if you're doing something drastic like switching from all-dry to all-canned, or all-commercial to all-homemade. Mix a little bit of the new food with the old every day, or introduce just a little bit of the new type food and monitor your cat's reaction. Let your cat determine the speed of the food switch. Many cats do all right with sudden, wholesale food change--my cats have never shown discomfort, and the poor bastards have had to put up with a lot of fucking around in terms of their diet--but it's definitely not uncommon for cats to get indigestion because of this. You have been warned.

Things to Avoid:

1. Don't get food containing by-products of any kind.
It's not that by-products are inherently bad so much as the quality control is terrible. The AAFCO definition of by-products encompasses a whole lot of different bits of an animal, which means the contents for each batch can vary quite a bit. I also think (and this is mostly personal opinion and some common sense reasoning here) that the risk of nutritional imbalances are increased when by-products are the primary or sole animal protein source. By-products tend to be high in ash and fat-soluble vitamins simply because they tend to contain a large proportion of organ meats. Pet food manufacturers compensate for this somewhat, but it's not unknown for pet foods containing by-products to contain astronomical amounts of certain nutrients that can become toxic at high doses, such as vitamin A, vitamin D and iodine. And now there's some evidence that excess vitamin D may quite possibly be responsible for feline odontoclastic resorptive lesions (a fancy description for a type of dental cavity that occurs around the crown ["neck"] of the tooth), since some very new research has shown that cats with resorptive lesions also have higher-than-normal levels of vitamin D in their blood. (But to be fair, the extremely high level of vitamin D in some cat foods is most likely due to overzealous supplementation, and not entirely to byproduct usage.)



2. Don't buy food that contains unnamed species in the ingredient list, e.g., "Animal Liver", "Meat Meal." This decreases the risk of Fluffy being fed Fido or Patches. The rest of the KMOV report can be found here, here and here.
   
   

3. Avoid the preservatives BHA, BHT and ethoxyquin. Even though cancer did not develop consistently in studies involving BHA and BHT, what was a consistent result was low birth weight and enlarged livers in long-term studies involving rats, and liver hypertrophy in studies involving rhesus monkeys.
   
   Ethoxyquin was a originally a pesticide and rubber stabilizer formulated by Monsanto. It's not allowed in human foods except to preserve the colors of certain spices like paprika at no higher than 100 ppm; the highest allowable ethoxyquin residue in meat and eggs suitable for human consumption is 0.5 ppm. The highest allowable concentration for pet food? 150 ppm. Quite a discrepancy, especially taking into account that cats typically weigh less than 1/10th of the average human, and it's not as if we're meeting our daily energy requirements through eating nothing but paprika and chilli powder.
   
   There's a fairly big loophole about the addition of ethoxyquin and other preservatives, by the way, so not seeing these chemicals on the ingredient list may not necessarily mean they're not present.
   
   Above and beyond the disputed toxicity and carcinogenicity/mutagenicity (the only major study on ethoxyquin in pet foods was performed by Monsanto, and it's been criticized for being flawed), I find the idea of feeding my cats nothing but foods containing preservatives day in and day out somewhat creepy, but this is because the philosophy I hold to when it comes to feeding companion animals is: If the quality isn't equivalent to what I would feed myself, it's not going into my pets, either. An advantage to canned food is that it rarely needs preservatives, because canning in and of itself retards spoilage.
   
   
4. Avoid soy if you can. Soy presents many different problems:
   
   It decreases plasma taurine in cats. Yes, manufacturers can compensate for that by upping the taurine that's added to the food. However, soy doesn't provide any unique nutrients that can't be fulfilled by other ingredients that won't interfere with taurine levels. Don't believe the hype, including the hype provided by "holistic" pet food companies like Wysong. Soy is included for one reason only in cat (and dog) food: it's a much cheaper protein source than meat, and is the only plant protein that provides a complete amino acid profile.
   
   Soy contains trypsin inhibitors, and since trypsin is one of the three primary enzymes involved in protein digestion, their presence poses a big problem, especially for an obligate carnivore like a cat. The normal cooking process doesn't completely deactivate these enzymes.
   
   Soy (along with most legumes and grains) contains large amounts of phytic acid. In fact, soy contains more phytic acid than any other legume or food plant studied. Phytic acid combines with minerals in the cat's digestive tract, thereby inhibiting their absorption. Again, normal heat processing doesn't destroy phytic acid.
   
   Soy contains phytoestrogens which have been known to cause damage to cheetah livers and reproductive systems. Yes, cheetahs are especially sensitive because they're notoriously inbred and fragile. However, the soy that caused problems in the studied cheetahs made up a fairly small proportion of their food, and cats in general are pretty sensitive to all sorts of wacky chemicals, up to and including estrogens.
   
   Soy also fucks with thyroid hormones. The elevation of T4 hormones documented in that study may or may not lead to hyperthyroidism down the line; since no controlled long-term study has been done (and probably never will be), there's really no way to know. But again: there are lots of good foods that don't use soy, so why not avoid it if you can? (NOTE: In a previous version of this page, I heavily implied that soy directly caused hyperthyroidism, and Khelmar very rightly smacked me down for it.)
    
5. Avoid foods that contain a lot of plant-based proteins or too much plant matter in general, especially starchy grains. Plant-based proteins like corn gluten meal are generally inferior in quality to animal protein, mostly because they're not as digestible and don't contain a good amino acid profile. According to this study, diets based on corn gluten meal are less digestible and also cause relatively more mineral losses loss compared to diets based on meat meal. And this other study suggests that corn gluten meal diets cause more urinary sediment compared to fish meal diets, and therefore may not be as effective in preventing struvite crystals. Grains and plant matter also contain relatively large amounts of phytic acid (see notes above on soy), and tend to contain more fiber than cats need, which in turn interferes with protein digestibility and mineral absorption. There are known cases of cats suffering from mineral deficiencies due to eating commercial dry food high in plant matter.
   
   
6. Try not to feed more more than 50% dry food in general (in my unprofessional but semi-informed opinion, not feeding dry food at all is best if you can manage it). Dry food absolutely sucks for cats for many, many reasons:
   
   It contains way too much carbohydrate. This is simply a matter of manufacturing logistics. Starchy grains and other plant matter are needed for the extrusion process, at least 40% usually. Cats, on the other hand, are pretty much unsuited to utilize carbohydrates since they evolved to derive their energy from protein and fat. They lack hepatic glucokinase activity, which is the enzyme responsible for aiding in the metabolism of large loads of post-meal glucose. They don't have amylase in their saliva, which is an enzyme that initiates the breakdown of complex sugars into simpler ones, and they produce only 5% of the overall amylase that dogs do. They lack fructase, another enzyme that's responsible for metabolizing sugar (in this instance, fructose). Cats on dry food only diets experience relatively large spikes in blood sugar, sugar their bodies can't deal with adequately, and this has very real consequences. Feline obesity is at an all-time high, with estimates of about 25% of the cat population being obese. The major predisposing factor for obesity? Dry food-only diets. Diabetes is also becoming a very real problem for more and more cats, and many researchers are now finding that high-protein diets (either wet food or presciption high-protein dry like Purina DM) help control this condition even better than the traditional high-fiber, high-carb prescription diabetes formulas, which were mostly based on human and rat research to begin with.
   
   And futhermore, the latest research now indicates that diets containing starch may contribute to struvite urinary crystal formation.
   
   Dry food generally contains inferior protein sources compared to canned or home-made diets. The animal proteins in dry food are often over-processed as well. Meat meals are cooked not once, but twice at extremely high temperatures: once to remove water and fat, and the second time during the kibble-making process. It's a simple fact that the more a protein is cooked, the less the digestibility is.
   
   Dry food also contains too little water, but I'll cover that in point number 4 in "Things To Look For."
   
   Dry food does leave behind less residue than wet food, and therefore may slow down the progression of dental plaque accumulation and periodontal disease. However, dry food in and of itself doesn't prevent dental disease, and it certainly doesn't "help clean teeth with mechanical brushing action." That's a bunch of marketing bullshit. there are plenty of cats on dry food-only diets who still need annual dental cleanings done. Here's a passage from Small Animal Clinical Nutrition on page 491 that addresses this specific subject:
   

   Many of the studies traditionally cited to substantiate claims that dry foods reduce accumulation of plaque and calculus are old reports that used small numbers of animals, had varying evaluation methods and did not report data analysis.
   
   Although consumption of soft foods may promote plaque accumulation, the general belief that dry foods provide significant oral cleansing should be regarded with skepticism. A moist food may perform similarly to a typical dry food in affecting plaque, stain and calculus accumulation (Figure 16-8). In a large epidemiologic survey, dogs consuming dry food alone did not consistently demonstrate improved periodontal health when compared to dogs eating moist foods.
   
   Typical dry dog and cat foods contribute little dental cleansing. As a tooth penetrates a kibble or treat the initial contact causes the food to shatter and crumble with contact only at the coronal tip of the tooth surface (Figure 16-9). To provide effective mechanical cleansing, a food should promote chewing and maintain contact with the tooth surface (Figure 16-9).
   

7. I'd avoid foods that are targeted specifically at certain lifestages, breeds or "lifestyles". I'd especially avoid feeding senior formula food. "Lifestage nutrition" is yet more marketing bullshit. Think about this for a second: once you were weaned and old enough to sit with the adults, did you get special "child-specific" food? I don't know about you, but I had to suck that adult food down and like it. Sure, there are foods that are associated with kiddies like sugary cereals, hot dogs and those god-awful Lunchables abominations, but it's not as if there's anything special about these foods nutritionally beyond their astronomical nitrate, artificial coloring, preservative and refined sugar content. Doctors don't go around telling parents "Feed your 8-year-old only Trix, because Trix is for kids!" And then when you get old, you don't get "senior-formula" food if you're still healthy. At worst the food is softer if you don't have any teeth left. This is true pretty much everywhere in the animal kingdom. Or at least it's true for vertebrates. There's no such thing as "Voles for Kittens" or "Mice for Senior Cats" running around in the wild. Yes, kittens need more nutrients and calories than adults do--but that's per lb. bodyweight, and kittens will generally eat more food per lb. bodyweight than adults too. That's how they (and just about every other animal) adapted to do to meet elevated nutrition requirements. And cats more than most animals tend to adjust their food intake with beautiful efficiency. A truly high-quality cat food is calorie- and nutrient-dense across the board, and you adjust the serving size based on age and size.
   
   Lifestage nutrition came about primarily for one very simple reason: shelfspace. The more visibility a brand has on a shelf, the more likely a consumer who's just browsing around will pick it up to try. One can only have so many different flavors. Lifestage nutrition now allows a brand to at least triple its shelf presence.
   
   To a certain extent, lifestage nutrition also allows manufacturers to spend some bucks making kitten food, and then cut down on the nutrient and calorie density by adding more fillers and still charging the same price.
   
   And at least one lifestage formula (senior foods) seems to be based on non-cat-specific (or at least flawed) research and assumptions. The traditional senior formula food is calorie-restricted, lower in protein and fat and higher in carbohydrates. This is consistent with rat, dog and human research that indicates senior animals tend to have slower metabolisms, have lower calorie needs and get chubby as a consequence. However, research now shows that senior cats actually have similar calorie needs as young adult cats, and in fact show impaired protein digestion, which means calorie-restricted, low-protein diets are completely inappropriate for healthy older cats. In fact, one major survey indicated that cats eating senior foods tend to be chubbier than the general population.
   
   And don't even get me started on hairball, "indoor-cat" and low-fat/high-carb weight control formulas and how bogus all that is. Dudes who make those weight loss formulas need to check out a recent study showing how cats fed a meat-based diet adapt fat their oxidation in response to increasing amounts of dietary fat.
   
   If you have to use a lifestage formula, I recommend using kitten food. This is especially true of dry food, since adult and senior dry food contains more carbohydrates and non-meat ingredients than kitten formulas.

Things to Look For:

1. The first ingredient in a truly high-quality cat food should always be meat from a named species. Meat has a better amino acid profile, is more digestible, and avoids many of the problems with plant proteins that I listed above. Try to look for foods that contain more fresh meats in their ingredients instead of meat meals, because as noted in point number 6 above, meat meals tend to be cooked more and therefore less digestible.
   
   
2. If the food contains preservatives, look for non-toxic antioxidants, e.g. mixed tocopherols (vitamin E) and vitamin C.



3. Look for a food that contains minimal plant matter, and is preferably grain-free.



4. Try to feed as much food as possible that contains more than 70% water. Why? Because the average cat's thirst instinct ain't for shit. This makes sense when you realize that cats evolved as desert mammals and adapted to get most of their water intake from their food. Their primary food source? Tasty little rodents, which like most other mammals, are usually about 70% water. As a consequence, when cats undergo mild dehydration they have extremely efficient kidneys that work overtime to conserve water by concentrating their urine. They don't adapt their water intake based on the water content of their food, they base it on the dry matter. The upshot of all this is that cats eating only dry food get 50% of the water of cats eating only wet food.
   
   An interesting consequence of this lack of water is the increased likelihood for cats on dry food diets to develop uroliths (urinary crystals) and feline lower urinary tract disease (FLUTD) of all sorts. Initial research indicated that diets extremely high in magnesium coupled with slightly alkaline urine could cause struvite urolith formation in healthy cats, so pet food manufacturers lowered magnesium levels and added urine acidifiers to their foods. And sure enough, struvite uroliths declined. But then number of reported calcium oxalate uroliths (which form in acidic urine and which seem to be more likely to form in cats eating low-magnesium diets) started rising. In fact, the University of Minnesota noted that between 1984 and 1995, CaOx uroliths went from 2% of all reported uroliths to 40%. And then more and more research showed that foods high in moisture worked better to prevent FLUTD of all sorts, including idiopathic cystitis (by far the most common form of FLUTD). When you think about it, upping a cat's water intake when it has uroliths makes sense. The more water a cat drinks, the more dilute the urine is, and the probablity for crystal saturation and precipitation decreases accordingly. Research in the 70s showed that hematuria (bloody urine) induced by feeding a high-magnesium diet was abolished when the water content of the food was increased to 80%. Nobody quite knows the exact mechanism of why wet diets prevent idiopathic cystitis better than dry, but there's speculation that it has to do with urine concentration and solute load as well.
   
   
5. For a cat, look for dry matter protein content of more than 38%.
This means that for the average canned cat food that has 78% water, you're looking for at least 8.5% crude protein content. Cats are obligate carnivores; they need insanely large amounts of protein in their diet because not only do they need protein for muscle repair and the like, they use it as their preferred fuel source as well. Some nutritionists talk about the "sparing effect" carbs have on protein in that cats will use carbs for energy in the absence of excess protein, but what these nutritionists are ignoring is the fact that cats need to use protein for energy since they primarily generate their energy via gluconeogenesis and are naturally insulin-resistant, which makes deriving energy from large amounts of carbs somewhat tricky.


6. Less than 10% calories from carbs whenever possible. You know why.
   
   
7. Feed a variety of flavors from as many different brands as your cat will allow you to. I was pretty amused when Small Animal Clinical Nutrition denigrated this practicse, speculating that owners probably have a misconception that complete and balanced commercial cat foods aren't truly complete and balanced. It's true that most of them are balanced in a fashion and all are technically formulated to meet AAFCO nutrient recommendations, but different brands and flavors can have extremely different nutrient profiles. And a varied, nutritious, species-appropriate diet is one of the cornerstone to a healthy life. Would anyone in their right mind eat nothing but Easy Mac N Cheese washed down with a multi-vitamin every day for every meal for all their lives? Don't believe the hype about how you need to feed nothing but Science Diet Nature's Best day in and day out so your cats can enjoy the full benefits of their about-to-be-patented superior antioxidant formula. Feeding a wide variety of foods cuts down on food addictions and does a better job of covering nutritional bases.
    
8. If you're a really paranoid bitch like me, make your own cat food. I think freshness is a greatly underrated virtue when it comes to food--not just pet food, either. You can definitely avoid feeding your cats 4D meats (Dead, Dying, Diseased, Disabled), and if your cat has food allergies or irritable bowel disease, it's one of the best ways to ensure that they're not getting anything in the food that could cause a flare-up. But you need to be very, very careful when making your own cat food. It can be the very best thing for your cats, or it can be the very worst thing. Don't be a stupid asshole and feed your cat nothing but texturized vegetable protein and canned mackerel. People like these are what fuel the fearmongering horror stories in books like Small Animal Clinical Nutrition, and why many vets blanch when you tell them you're feeding your cats a home-made diet. Read a bunch, ask questions, talk with a vet who's well-versed in feline nutrition, use common sense once you have the basics down, do only what you're comfortable with and are sure you can cope with, and if you want, start out with a pre-packaged supplement like Feline Future Instincts TC to begin with so you get a feel as to what it's like to make your own cat food. More information on how to join the dark side provided in the links section.

Bitch, I'm Clicking Those Ruby Red Shoes Already