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I heard a local veterinarian to say that Whiskas can cause kidney disease. I tried to research that claim, but so far I haven't been able to find academic articles dealing with this issue, even though there is a vast amount of anecdotal evidence.

I was wondering if anyone knows for certain if this is true or false. Apparently, older cats have propensity to suffer from kidney disease. However, some people say veterinarians have told them that Whiskas was responsible for the death of their cats. I suppose that veterinarians know about the incidence of kidney disease in cats, so it is surprising to read that kind of blanket statements being made by professionals.

Some people say that taurine is to blame. However, taurine is classified as an essential nutrient by the VCA Animal Hospitals. Others say that dry food or fiber is what makes cats sick, but again no evidence is offered to support this view.

UPDATE: In response to @DanS:

[...] Do some more research, are the salt levels [in Whiskas] high (magnesium etc.) are the protein levels high?

It is hard to answer precisely your question. As far as I know, there are not guidelines on daily recommended intake for cats. I even found some opinions saying that nobody knows (e.g. here). However, when it comes to protein there seems to be a magic number: 36%. It almost seems that food companies strive to reach that number. Of course, the question should be: 36% of what? In the package I bought, it says that the recommended amount is between 45g and 90g depending on age. This is equivalent to 16g and 32g of protein, respectively. Keep in mind that the product I bought is intended for kittens. Now, the only table of values I found was published (pdf) by FEDIAF (page 17.) It says the recommended amount of protein is 25.0g for adults and 28-30g when cats are still growing per 100g of dry food. As you can see, if my package contained 100g, it would have 35.5g of protein, an increase of 15% with respect to the highest recommended daily intake given by FEDIAF. Is this a significant increase? I don't know.

As for salts, I only know that Whiskas contains iodized salt but the product I bought doesn't say the amount. Other ingredients are specified in another paragraph but without percentages or amounts.

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    Whiskas uses the same ingredients as a bunch of other commercially prepared cat foods, so I don't know why a veterinarian would single it out as particularly bad. Did they mention wet or dry in particular or was it the whole brand? – Zaralynda Jul 25 '14 at 22:56
  • The veterinarian I know, singled out Whiskas in general. Some comments I have read, take issue with dry food, but that is not a generalized opinion. – Robert Smith Jul 25 '14 at 23:07
  • @RobertSmith in terms of salt I don't just mean NaCl but the total mix of anions and cations. Specifically excess magnesium and phosphorous (both necessary) can be deleterious to kidneys. On excretions phosphorous frequently exits as phosphates and insoluble ones like CaPO4 can cause problems. – Dan S Jul 26 '14 at 0:48
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    30-40% of the calories (35% is good) should be in the form of protein for normal cat food. If your cat has kidney problems I'd recommend LESS than that. Also check the ingredients and try to reduce vegetables, sea food, fish. The sources should be red meat or poultry. – Dan S Jul 26 '14 at 0:50
  • @DanS Sure, but the product doesn't specify very much about salts. I think phosphorous is the only one with 0.72g. This is very near the recommended intake of 0.84 given by FEDIAF. After conversion using 100g of dry food, it gives 0.8g. Again, without hard facts of what constitutes a good diet, these numbers are hard to interpret. – Robert Smith Jul 26 '14 at 0:59
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Whiskas generally contains the same ingredients (sourced from the same locations) as many other commercially available cat foods.

This fact was made very clear during the 2007 Melamine Pet Food Recall as pet owners feeding nearly every brand scrambled to find something safe to feed their pets as we learned that "two Chinese nationals and the businesses they operate, along with a U.S. company and its president and chief executive officer" contaminated wheat gluten with Melamine to make the protein content appear larger.

If there were any scientific studies to specifically point at Whiskas made public, I'm sure they would reformulate their product (to sell a product known to make cats sick would loose money). The vet may be suffering from a type of confirmation bias, where cats in that area tend to be fed cheap food, and so the vet sees a lot of elderly cats fed cheap food develop kidney disease and thinks that it must be caused by the cheap food. It's hard to prove a negative and cats who eat Whiskas do develop kidney disease. Cats who eat everything develop kidney disease if they live long enough.

Some Relevant Studies

A literature review from 2011 stated:

There are many documented causes of kidney disease in cats, but few of the identified aetiologies [causes] seem likely to explain the vast majority of cats with CKD. No risk factors (other than increasing age) have been consistently identified and CKD has been described in different continents with presumably different infectious, nutritional, husbandry, genetic and environmental influences.

  • Feline chronic kidney disease: Can we move from treatment to prevention? Joanna D. White, Richard Malik, Jacqueline M. Norri The Veterinary Journal 190 (2011) 317-322 web abstract

The most complete study that I can find discussing risk factors used questionnaires to review owner's recollections of the past 3 years of a large amount of diet and lifestyle variables to develop models to predict (retrospectively, they already knew who had it) kidney disease. Only 38 cats with kidney disease and 56 control cats were studied.

None of the lifestyle variables were significant in this small, exploratory study. Several diet variables were significant predictors of CRF, alone and in specific combinations. Increasing fiber in the diet appears to decrease the odds of CRF. Factor-2 was significant, with increased odds for lower levels of protein, fiber, magnesium, and sodium, and higher levels of ash. This demonstrates that patterns of usual dietary intake — and not just individual nutrients — might be important when considering the etiology of CRF.

(One way to analyze a large number of highly correlated data, such as the nutrition profile of several different commercially prepared cat foods, is to project the data onto an eignvector and use that as a variable, so that's why Factor-2 appears here. The effects of lower protein, fiber, magnesium, sodium, and higher levels of ash all happened together and could not be separated. The effect of Factor-2 on the model may be the result of some or all of these variables, or them occurring together. It's not known).

That said, the evidence for fiber and Factor-2 is pretty weak. The table for the 3 models developed during this study is below, and the 95% confidence interval (CI) for the odds ratio (OR) includes 1, which means that the odds of having kidney disease aren't affected by the variable (in this case, fiber or Factor-2).

enter image description here

Remember that this study has some flaws (small sample size, retrospective, selection bias, not randomized/blind/etc, based on human recollection), and it has not identified cause, but likelihoods.

  • Diet and lifestyle variables as risk factors for chronic renal failure in pet cats K.L Hughesa, M.R Slatera, S Gellera, W.J Burkholderb, C Fitzgeralda, Preventive Veterinary Medicine Volume 55, Issue 1, 10 September 2002, Pages 1–15 web abstract
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  • By the way, in the second study you cite, you are suggesting that they analyzed commercial food. Do you know if Whiskas (or some other widely known brand) was included? – Robert Smith Jul 26 '14 at 1:12
  • @RobertSmith It doesn't say what food brands were fed. They didn't directly analyze the food either, they asked the owners what brands they fed, then looked up the values in Animal Nutritionist (a software program) – Zaralynda Jul 26 '14 at 1:16

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