You have probably heard statements similar to one or more of the following:
"BARF (Biologically Appropriate Raw Food)? Stay away from that, there is way too much protein in it! With this kind of feeding, you are causing kidney diseases for your dog!"
"The overdose of protein in BARF causes kidney and liver damage!"
"Your puppy will grow way too fast due to the excess of protein in BARF and it will suffer from problems in the musculoskeletal system!"
Usually, there is no proof for the accuracy of these statements provided along with them. And as will be shown, these allegations are unfounded.
This is going to be a bit nerdy, because one needs to do some math in order to proof or disproof those statements.
At first, let us see if an oversupply of protein would be damaging for the kidneys or the liver (given, there was actually an oversupply)
"The question of the extent to which a long-term massive protein oversupply can lead to organ damage, especially of the liver or kidneys, is controversial..." *
This quote stems from the book "Nutrition of the Dog" by Helmut Meyer and Jürgen Zentek, the standard work on dog nutrition.
What it means:
It's not clear whether even a massive protein oversupply is harmful at all. So it seems like there is no such thing as an "overdose of protein" to begin with.
Now, let us ask ourselves the question:
What would be a possible definition of a "massive oversupply"?
According to the above mentioned book, an "extreme" oversupply is given if the consumption of protein is more than 20–30 g of protein per kg body mass (BM).
Of course, the meaning of the word "extreme" is not necessarily the same as "massive", but I think we can agree that it still resembles an amount that is way higher than the normal amount needed.
So for the further analysis of this topic, let´s define a "massive oversupply" as an amount being 5 times the amount needed. Just keep in mind what has already been stated above: Even with this amount being exceeded it is questionable whether it would be harmful to the dog...
Side note: It does not make sense to consume an unnecessarily high amount of protein as there are no advantages in doing so and the protein metabolization always takes up the liver and kidneys, even if it is not clear whether this could actually become a problem in the long run.
How high is the protein requirement of a dog and when is it "too much"?
According to the book mentioned before, the daily protein need in the maintenance metabolism (the one in which the body is enabled to fulfil all life processes, e.g. breathing, digestion, movement) is calculated with the following formula**:
5 g CP x BM^0,75
"CP" stands for digestible crude protein
"BM" stands for body mass in kg
"^0,75" stand for high 0,75
According to this formula, a dog that weighs 28 kg therefore needs
5 g x 28 kg^0,75= 60,9 g of crude protein per day.
(NOTE: In cases of physical exertion, during growth, pregnancy or in the lactation phase, the protein requirement of a dog increases).
As stated previously, even if and when this amount would be exceeded, it does not mean that there is an oversupply. For that to happen, certain maximum amounts would need to be exceeded. Unfortunately, these maximum amounts, however, are not (yet) defined in more detail for protein.
But let´s use our definition in which 5 times the daily amount of crude protein needed is considered as a "massive" oversupply. Then the formula for a 28 kg dog looks like this:
25 g x 28 kg^0,75 = 304 g
Using the book´s description of "extreme" oversupply (= daily 20 to 30 g per BM), then it would be even more: 560 g to 840 g protein!
This represents up to almost 14 times of the calculated amount needed (= 60,9 g/day). Also, given that the average amount of protein in meat is ca. 20 %, 560 g protein resemble an amount of ca. 2,8 kg of muscle meat (and 840 g resemble 4,2 kg). That is A LOT of meat to eat!
How much protein is in dry food?
If we look at BARF and its risk of providing too much protein, we also have to have a look at the protein supply for dogs that receive ready-made food for comparison. Ready-made food is considered to be ideally put together and tailored for the needs of dogs.
For this comparison, some dry foods (which are all available in Iceland) were selected as examples and the rations for a 28 kg dog (large breed) were calculated according to the manufacturer's instructions (data as of 06/2024).
In order to be able to compare the amount of protein, we need to look at the absolute content of crude protein in g supplied with the food. This is necessary because, as the name suggests, dry food almost completely comes as dry matter, while BARF is considered wet food. It is therefore not possible to simply compare the percentage of crude protein stated on each package. However, if you calculate how much protein is consumed daily, a comparison is actually possible.
And now tell me: How much protein is in BARF?
Let us look at a typical BARF ration for a 28 kg dog. Tripe is replaced 1:1 by meat as tripe is rather expensive in Iceland and hard to get. The meat contains about 15% fat, so we calculate some extra fat to reach an average of 20% fat in total for a dog that is active for 2 to 3 hours per day. Since there is extra fat added, the amount of meat is reduced accordingly. This dog also gets an egg per week. In addition, the dog receives fish oil, cod liver oil and small quantities of seaweed. However, none of the latter components contribute significant amounts of protein.
Here, too, the absolute amount of protein consumed has been calculated.
SIDE NOTE: Just for comparison reasons the same calculation was done for a BARF ration without extra fat with just muscle meat that contains 15 % fat (which would be sufficient for a dog that e.g. moves less). Here the protein per day is 105,1 g (less fat results in more meat and therefore more protein).
As it was to be expected: BARF does not provide too much protein. The ready-made food sometimes even provides more crude protein than BARF.
As a matter of fact, there no such thing as a "massive" or an "extreme" oversupply in BARF rations. We calculated and stated before that a 5-fold coverage of the protein amount needed would be 304 g per day and that could be described as "massive". This amount is not achievable with BARF at all!
Why does ready-made food sometimes provide even more protein than BARF?
The calculated protein need for dogs refers to the need for digestible crude protein, meaning protein that can be digested 100 %. If protein is digestible by 100 %, then it is high quality protein. The lower the digestibility, the lower the protein quality.
If food does not provide enough digestible/high quality protein, then more of the low-quality protein it contains must be supplied to meet the demand. Feedstuffs such as carcass meal or corn gluten, which are often used in ready-made food, have a digestibility of 50-70 % – in contrast to meat, which can be digested up to 98 %. Therefore, ready-made food must contain more protein.
Why is the argument still repeated over and over again, when the calculation shows that it is not true?
Maybe it's simple panic-mongering, but it's more likely that many critics never did the math. Some people don't seem to realize that meat is actually only 12-24 % crude protein.
Perhaps it is also due to the fact that most critics are not informed about how a BARF ration is composed in the first place. Of course, if you were to give a 28 kg dog 720 g of pure chicken breast a day and nothing else, he would probably develop kidney and liver problems in the long run. But firstly, this is not BARF and secondly, the health problems would then not be the result of the exaggerated supply of proteins, but from the absence of an adequate energy source. In such a case, the body has to use proteins for energy production, which leads to the increased production of ammonia and ultimately urea, which in return can stress the liver and kidneys. If there is enough fat in the ration, this is not necessary. This reduces the amount of meat and improves the so-called protein-energy ratio.
That's why BARF always points out that the dog needs a source of energy and that's why the BARF plans always talk about streaky muscle meat (about 15-25 % fat) or it is recommended to add fat if only lean meat is available.
Only those who ignore the rules of the BARF concept may feed excessive amounts of protein. If you don't stick to the rules, you don't do BARF - it is rather doing some pseudo-BARF or some other kind of raw feeding.
Summary
The calculations clearly show that BARF does not contain too much protein.
On one hand, because protein cannot be overdosed under normal circumstances and on the other hand, because there is simply not too much protein in a BARF ration.
If you do the math, you will find out that a little more protein is supplied than would be absolutely necessary to cover the basic needs. But you will realize as well that in ready-made food similar - if not higher - amounts of protein can be found.
Accordingly, the prejudice that BARF would put too much strain on the dog's kidneys or liver due to too high amounts of protein is simply unfounded.
It is always good to do the math...I love math!
* Meyer/Zentek (2013): Ernährung des Hundes, S. 67
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