Kidney Disease in Dogs Part 2 – Question Low Protein Dog Food

So you know now why your dog or cat is in kidney failure, the main reason being dry dog food but secondarily it can follow some chemical insult. If your vet now recommends a low protein dog food, particularly a dry one, to benefit his failing kidneys, you should be more inclined to strongly question this advice. But it gets worse. If you’ve heard enough and are ready to start your new raw life, please jump to Kidney Disease in Dogs Part 3: The Solution.

Vets Are used to looking at the bloods of animals fed minimum protein diets…

Conventionally trained vets are taught that when protein rises in the blood it means the liver and kidneys may no longer doing their job properly, one or both is packing it in. Protein is used as a useful bio-indicator of what might be happening under the hood. Nothing wrong so far. 

The problem is people are starting to feed their dogs like the little meat-eaters they most certainly are, to the great benefit of their health. This means a diet of lots of protein and a little fat (for example a rabbit, should you suck all the water out of him, is perhaps 70-80% protein and 10% fat. While many pre-made raw dog foods produce excellent product to this protein:fat ratio many of the cheaper brands (and indeed our mixes we make ourselves) are usually a little fattier. 

a dog taking a steak off a plate

Compare this natural diet to dogs fed cereal-based fed dogs. These animals must exist on a diet of 18-22% protein, the minimum you can use in you food and state it is “complete by AAFCO standards”. The rest of these products are cereal, around 50-60% carbohydrate.

These are two very different feeding styles with one getting lots of protein and the other the minimum required. It should thus come as no surprise that when their bloods are tested, raw fed dogs have significantly more protein in their blood, around 20-30% more.

This rings alarm bells for your conventionally trained vet who has been using for their comparison laboratory dogs fed standard, cereal-based diets, food that is desperately low in proteinAny dogs fed a slightly more luxurious diet containing more meat always risks appearing to have “excessive levels of protein in their blood” to these animals but not because they are sick, it’s just they’ve been eating more.

The theory coming from dry food manufacturers and the vets they educate is that this extra blood nitrogen risks creating an extra load on the kidneys, as it’s them that need to filter all this “excess protein” from the blood. Your vet then reaches for the low protein dry food to try and control this rise. Makes sense, doesn’t it?! 

And the theory has a tiny bit of weight in that there are one or two instances in the treatment of human kidney disease where low protein is recommended. These are just before beginning dialysis (after which they are advised to increase their fresh protein intake to normal levels afterwards, and something dogs can’t do anyway) or if you have proteinuria (very dangerously high blood urea nitrogen, which in dogs is a BUN level of 80. This in itself is not only rare, but an indication that the dog is in the vey end stage of kidney failure and in serious trouble. Yes, low protein at this time is sound advice). 

But what of every dog in between?! 

Irish kelp for dogs

Studies Show That Even With Their Kidney Function Reduced by 90% They do Better on Higher Protein Diets.

Somewhat unsurprisingly as they are meat eaters, studies show dogs thrive on high protein diets (Robertson et al. 1986, Bovée 1991, Finco et al. 1994, Hansen et al. 1992, Laflamme et al. 2008). In fact, their ability to process protein is so efficient, that prior to feeding them the high-dose protein diets, many of the studies authors cited above actually removed 75% (and as much as 90%) of the kidney function in healthy dogs (by chopping off supply to the rest of the organ), to replicate chronic kidney failure. All these studies unequivocally prove that dogs with CKF can safely deal with and do better on higher protein diets than low protein dog food.

…renal function and biochemical responses to dietary changes were studied in four dogs with stable chronic renal failure. The objective was to determine if dogs with moderate stable failure adjust to diets with varied protein and electrolyte content. These dogs were found to have the capacity to adapt to a wide range of dietary protein and electrolyte intake. The only exception was found in dogs fed a reduced-protein diet, which failed to appropriately adjust renal tubular excretion of sodium and phosphate. The only advantage of reduced dietary protein in this study was a reduction in blood urea nitrogen (BUN). Disadvantages of reduced-protein diets were reduced glomerular filtration rate (GFR) and renal plasma flow.

Bovée 1991

There is just one study I can find that seems to disagree with the above. Upon finding 10 cats suffered kidney disease on a higher protein (40%), commercial dry diet, DiBartola et al. (1993) replicated the diet in 9 laboratory cats. They note that phosphoric acid was added during production, as was the case in the first diet. In just two years, three of the nine previously normal cats suffered renal dysfunction and renal lesions. However, we cannot say for sure what the problem is here. Maybe it was the presence of phosphoric acid added to the mix. We know that it is the inorganic forms of phosphorus used in dry foods (monosodium and dicalcium phosphate) that affect postprandial plasma phosphorus in cats (Alexander et al. 2018, Coltherd et al. 2019), NOT phosphorus occurring naturally in food items such as meat or vegetables seems to have little to no effect whatsoever (this is crucial for your diet advice going forward, we will revisit this in Part 3).  

As always, the science supporting dry food is dangerously out of whack..

Dry food companies emblazon on the front of their food bags “clinically proven to benefit kidney disease in dogs”. There is no mention of the study on the bag. Were they talking about dogs in proteinuria whereby a lower protein diet might of helped? Or is that they reduce the salt content of their kidney food which would instantly make the kidneys happy? Or is the food more digestible? Or less antigenic somehow? Maybe it’s wheat free, that’d be nice. Or maybe the manufacturer who conducted the trial in-house put the decimal point in the wrong place and the food didn’t help at all. What we’re missing is actual evidence. It’s worrying our vets are not asking for this.

The fact remains that vets and dry food companies are the only people calling for low protein diets as a starting point to treat kidney disease in dogs (and senior dogs, God don’t get me started there). Now it happens that protein is expensive compared to carbohydrates. This is why most dry dog foods include so much cereal. By incriminating protein they can include even more cheap carbohydrate filler. Crystals aside, all these carbs convert to sugar in the blood which is balanced by lots of insulin. Excess insulin and soon insulin resistance contributes to the metabolic syndrome that is associated with the development of kidney disease too. 

It’s all wrong.

OK, I think I have been as clear as I can. Dry food is absolutely not recommended here so let’s take a look at what you should do!

References Used but Not Linked

ANTECH Diagnostics (2003). ANTECH News, online journal, June 2003

Finco, D. R., Brown, S. A., Crowell, W. A., Brown, C. A., Barsanti, J. A., Carey, D. P., et al. (1994). Effects of aging and dietary protein intake on uninephrectomized geriatric dogs. American Journal of Veterinary Research, 55: 1282–1290

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