SheltieGuy
Forums Enthusiast
Ok, let's do this thing. Some of this is pretty much 'What she said' to Dr. Shelli's post in terms of the potential renal hazards of high protein diets... I'm just gonna take longer.Some , however, is more speculative.
For starters, we have to review our high school biology. i apologize if this is overly simple, I know that the people here take pains to be well informed, but many years of being a veterinarian has taught me to 'demistify' - that is too simple is far better than too complex. Far better, when an animal's condition is explained, that an owner walk out thinking, 'Well, Duh!' than 'Well.....Huh??"
So what is a carbohydrate? It is , not surprisingly, hydrated carbon - that is C + H2O. The most important carb, the simple sugar glucose, has 6 molecules of each, so C6 H12 O6. Glucose is THE energy source for cells. They break it down by a process called glycolysis (glucose lysis) to turn the C6 H12 O6 into CO2, H2O and energy. And that energy is what fuels us.
Take home message - whether you eat sugar, starch, protein, or fat, if the cells are using it for energy, they get it for their use as glucose. Period. This is why statements like ' Don't give cancer patients carbs, because , unlike protein, they digest as sugar,' are misinformed.
So what is a protein? To the C-H-O of carbs we add nitrogen, in the form of NH3, or an 'amine' group. (As in 'ammonia', or NH4. An amine group is basically an ammonia molecule.) This converts our carbs into 'amino acids', the famous 'building blocks of proteins.'
Proteins are used by the body in 2 ways - 1) They are used to create proteins- build tissue, replenish red blood cells etc. etc. and , 2) the important part for our discussion - if you eat more protein than you need for protein creation,they undergo 'deaminization' (amine removal) where the amine is ripped off and the remaining carb is used like any other carb - converted to glucose and shipped to the cells.
Deaminization requires energy, which is the idea behind the Atkins Diet. if you eat 300 calories of baked fish, and 300 calories of bread, you end up with more calories from the bread because you have to spend 50 calories converting the protein to carbs.
Take home message - having to use proteins for energy is not efficient nutrition. it's rather like Jack Nicholson in 'Five Easy Pieces' ordering a turkey sandwich and throwing out the lettuce, tomato, and turkey because what he really wanted was a piece of toast.
So, okay, the body has to do a little extra work. May keep my dog trim. Hey, it's protein! Make him big and strong and healthy. What's the problem?
The potential problem, and all the controversy, comes from all those amine groups that are left over after being ripped off. They rapidly convert from amine to urea, and await being eliminated by the kidney. And, yes, that most dreaded test for anyone with a dog with renal disease -the BUN- means Blood Urea Nitrogen - it is simply a measure of the buildup in the blood of all of those extra chopped off bits, and when it starts to rise you could be in big trouble.
Anyone hearing just a little bit of an alarm bell about feeding ultra high protein diets yet?
Now, sure, a normally functioning kidney can clear a tremendous amount of urea from the blood, and can handle this with no problem. But this is the famous 'taxing the kidney' or 'stressing the kidney' issue. its a bit like saying ' After he's finished his chores I make my kid carry a big rock back and forth across the field for an hour. Heck, he's young and strong, he can handle it.' Similarly, if the kidneys are in good shape, yes, they can simply work harder and keep all that unnecessary urea from building up to dangerous levels. But why in the world would you want to do that? What is the advantage?
And, as Dr. Shelli pointed out, if the kidneys are less than optimum, and this is a difficult thing to determine, the extra load from excess protein is certainly not good.
She mentions 30%, I learned more like 21%, (but she is probably correct.) And its a threshold thing. if you need 21% and you have 25% you will not notice a problem. (This is why a healthy individual can safely donate a kidney.) But you drop to 15% and BUN/creatinine start to rise ominously. In addition, if the kidneys are somewhat marginal, say in the 35% range, they will show nothing on routine tests, but in the presence of stresses like dehydration, or just the 'stress of stress', as for example being boarded where both those are likely to occur, then the kidneys will be pushed over the edge.
These are very real concerns.
'Common knowledge' for the past 50 years has been that the standard protein requirement for dogs is about 20%, perhaps 26% for growth, extreme activity etc. Now, of course, 'common knowledge' is often wrong and always subject to reconsideration, but this standard seems to have held up well. Dogs on 20% protein are not hypoproteinemic, (low blood protein - and we measure blood protein levels on every Chem screen), they maintain good muscle mass and show no other indication of protein deficiency. As the 20% certainly seems more than adequate for the 'protein building' role of dietary protein, much above that simply results in deaminization and lots of extra urea to deal with.
Given that the kidneys are usually the first organ to go in the degenerative diseases of the geriatric dog, why are we overworking possibly compromised organs? Testing BUN and Creatinine every 6 months is all well and good, but if you see them start to rise that tells you, in my opinion, that you should have stopped feeding the excess protein 6 months ago, because damage has been done. At the very least I would throw in a microalbuminuria test on the urine every 6 months, which can pick up renal disease before the BUN starts to rise.
Final thoughts- There is of course another side to the argument, which I respect. Science and medicine aren't about 'me right- you wrong', its about getting to the truth. A dog has to get energy from some food ingredient, and if not protein then the options are carbohydrates or fat. The concept of 'protein for protein creation and some energy, carbs for the bulk of energy production' can be challenged by 'protein for energy, don't worry about the kidneys, dogs are designed to handle it, carbs are simply bad.' That is a bit of 'another story for another time'. The point of this little epic was to point out the potential pitfalls of ultra high protein foods, especially when we want our pets to live for 15 years, which is a substantially longer life than that for which their kidneys were probably designed. - Dr. Mac
Correction, criticism, alternative reasoning welcome, and will not be taken personally.
I for one am VERY GRATEFUL for your informative answer.. I cant thank you enough for taking the time to explain this all to us ..
I will let my pup finish his TOTW (32% protein) then give him a lesser (20ish%). I think i am going to switch to FROMM.
AS i have said before this kidney issue hits home for me in a big way... Thank you soooooo much for helping us understand !
