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. 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.

Low Protein Dog Food For Kidney Disease Goes Against All The Available Independent Literature on the Subject…

Dogs are carnivores. That means they eat other animals, as animals are made up of protein and fat (e.g. a dehydrated rabbit is 70% protein and 30% fat, very roughly!). This is all they need, as dogs have no need for carbohydrates from external sources, which are derived from plants. In fact, dogs can make their own carbohydrates from protein and fat in a process called glycogenesis.

a dog taking a steak off a plate
Dogs are carnivores, they thrive on high meat protein diets not low protein dog food

So dogs, by their very nature, are protein eating machines that consume a lot more protein than omnivorous humans who eat both plants and animals. Raw fed dogs, that is dogs fed a biologically appropriate diet of fresh meat and bone containing 70% protein, consume a lot more protein than dry fed dogs who exist on a diet of 50% cereal (i.e. 50% carbohydrates) and, the legal minimum of, 22%  protein, most of which is plant derived. All this protein gets eaten, digested and then absorbed into the blood. Tests have shown that raw fed dogs have higher blood urea nitrogen (BUN ~20 mg/dl, n = 227) than cereal-based dry-fed dogs (16 mg/dl, n = 75; ANTECH 2003).

The theory coming dry food companies is that this extra blood nitrogen creates an extra load on the kidneys, as they need to filter excess protein from the blood, so it should be avoided in favour of low protein dog food. This theory stems from the fact that in a small number of human kidney disease patients, this is what they are advised before beginning dialysis (they are advised to increase their fresh protein intake to normal levels afterwards) or if you have proteinuria (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 latter end of kidney failure and in serious trouble).

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

As meat eating carnivores, dogs are shown to 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 high, 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

The Bovée finding above might explain some of the confusion. Dogs fed higher protein diets have higher levels of BUN and creatine in their blood. This is absolutely to be expected. Dodds, one of the world’s leading canine haematologists has been telling us this for some time. If vets continue to compare dogs fed biologically appropriate diets high in meat protein to laboratory dogs fed dry, cereal-based diets desperately low in protein then they will always think the former will have “excessive levels of protein in their blood” which MAY be in an indicator of renal failure. It MIGHT be in dry-fed dogs but it’s NOT in raw fed dogs. It’s just they’re eating more. As the other studies above show, renal function is actually improved on these diets.

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 3 of 9 previously normal cats suffered renal dysfunction and renal lesions. However, they and we cannot say what the problem was here. Was it the presence of phosphoric acid added to the mix, as the authors noted, or was it aggravating factors common to dry food such as a lack of water, the presence of carbohydrate, or high salt, or a great number of other factors happening in tandem, or was it simply that the cats kidneys can only take so much denatured meat meal in it’s food each day? We don’t know.

badge stating scientifically provenThis Draws into Question the Wisdom of Taking Lessons Learned from Feeding Omnivores (Humans), and Employing Them Directly Upon Carnivores…

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 evidence.

The fact remains that dry food companies (and those educated on their literature) are the only bodies calling for low protein diets as a starting point to treat kidney disease in dogs (and senior dogs ). Now it happens that protein is expensive compared to carbohydrates. This is why most dry dog foods include so much cereal thereby reducing the pesky protein content down to where it  resides today which is around the 22% protein level, the legal minimum you can put in a food and call it dog food, not the optimum (more here Where Are the Pet Food Police) so they’ve made clear that they are not great fans of using this expensive ingredient.

Ironically by reducing the protein content they are thereby increasing the carbohydrate content for the little carnivore. At 50% carbs, your average dog is already consuming double the amount of carbs in every meal that you as an omnivore are recommended to eat per day. All these carbs convert to sugar in the blood which is balanced by lots of insulin and constantly high blood insulin is strongly linked to kidney disease in humans. We already know from our article pancreatitis in dogs that the carnivorous dog is suffering terribly from the high dose carbs it is currently being fed so this doesn’t bode well for his kidneys.

The cynical among us might say that protein reduction in senior diets and for those with less than 90% chronic kidney failure is an extremely questionable cash savings exercise. Others say that the dry food companies are getting confused with phosphorus which is hard on struggling kidneys and should certainly be addressed and lowered in a dog with kidney disease. The two words do look quite similar. I’ll leave you to make up your own mind on this one.

OK, so I know the cause of the issue and what I shouldn’t feed, so what should I do?! Let’s take a look…

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