Dogs need vitamin A (or more precisely: retinol), because it is an essential vitamin for them. Vitamin A is one of the nutrients that can indeed be overdosed and overconsumption (“hypervitaminosis”) can be associated with tooth loss, liver damage, miscarriages, loss of fur and even death.
Is there a vitamin A overdose in BARF? Spoiler: No!
Critics often warn of "BARF" saying that the use of vitamin A-rich ingredients can quickly lead to an oversupply of vitamin A. In a BARF-ration, cod liver oil (lýsi) and liver and - far behind in terms of quantity - eggs, fish as well as meat contain vitamin A. And many BARF-feeders do feed all of these ingredients. That must lead to an oversupply, right?
Is it actually possible to overdose retinol/vitamin A with a normal BARF ration?
This is because dogs are very insensitive to vitamin A compared to us humans.
This is shown by the so-called safe upper limit or nutrient maximum. The meaning of it: As long as this amount is not exceeded, there is no overdose. For vitamin A, the NRC (National Research Council, USA) has set it at 2.099 μg per kg metabolic body weight per day for dogs in their maintenance metabolism. This is very abstract, so let us take a look at a few examples.
Let's consider a 30 kg dog. The safe upper limit for this dog is an incredible 29.906 μg of vitamin A per day!
Can we reach that amount with BARF? Let´s look at teh table below:
As you can see, the safe upper limit is not achieved, neither with BARF, nor with dry food – it is not even close! Also, the use of cod liver oil is also unproblematic. Even if you were to cover the entire amount of innards needed in a BARF ration with liver alone (72 g per day in our example) and you would add 2 teaspoons (ca. 10 ml) of cod liver oil per week on top of that, you were far away from the safe upper limit. Of course, you have to keep in mind that the vitamin A concentration of liver can vary greatly, because it is a natural product. But even if you happen to get only liver pieces that contain a lot of vitamin A, you won't reach the safe upper limit with a normal BARF ration plus 10 ml of cod liver oil per week.
If you wanted to poison a dog with vitamin A, for example, you would have to feed 500 g of liver per kg of its body weight every day. The 30 kg dog would get 15 kg (!) liver each day. An amount that probably not even a Labrador would be able to eat😉.
Why is there so much vitamin A in the foods?
The high coverage of vitamin A in all the constellations above is of course striking.
Why the coverage is so high in dry food can only be guessed. In the case of BARF, the high amount goes hand in hand with the natural structure of a prey animal. If you look at a rabbit, the proportion of liver is ca. 3,3 % of the body weight. This is what a BARF ration is based on. The 600 g BARF ration in our example contains an average of 23 g of liver per day. If you would try to feed only as much liver as you need to meet the vitamin A needs, you would only be able to feed tiny amounts of liver. At the same time, however, this would lead to a deficiency of other important nutrients, e.g. copper, manganese, vitamin D and various B vitamins. So not only is it unnecessary to reduce the proportion of liver, because the safe upper limit of vitamin A is not exceeded. It is even disadvantageous, because other nutrients could then be missing.
Vitamin A coming from beta-carotene
Dogs, just like humans, are able to convert B-carotene into retinol. B-carotene is found in carrots, sweet potatoes and other fruits with an orange-yellow colour.
This means that a dog is not necessarily dependent on liver & Co. for vitamin A supply. It could technically also survive with carrots.
What happens if you add carrots to all the vitamin A that is already in a BARF ration (or even in a dry food)?
Absolutely nothing happens. The body would only convert B-carotene into retinol if it is needed. If the dog already gets retinol, the body does not convert B-carotene. So you can simply ignore the amount of vitamin A that is in the fruit-vegetable mix.
Vitamin A supplements
In contrast to a normal amount of liver oil and cod liver oil in a BARF ration or in fruits containing B-carotene, the additional feeding of supplements containing vitamin A can be quite problematic. Sometimes it is not even obvious at first glance that vitamin A is part of the ingredients of supplements. It could be hidden in the "nutritional additives" section. So this is something to watch out for.
Conclusion
Vitamin A can be overdosed and if done, it can lead to severe health problems.
However, this is not possible with a normal BARF ration.
Even if the entire amount of innards in a BARF ration would consist of liver and the usual amounts of cod liver oil (“lýsi”) are added on top, you do not even get close to the so-called safe upper limit. Even compared to dry food, an average BARF ration does not provide more vitamin A.
The concern and prejudice that BARF rations overdose vitamin A are unfounded.
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