Vitamin A Toxicity

Does hiding pills in liver risk vitamin A toxicity?

Some of the information presented on the internet can sound alarming. This is especially the case when it comes across with a tone of authority and conviction. More often than not, I find out about the latest worry via emails sent to me during any given week. The latest concern to cross my desk has to do with liver being used as a way to hide medications for dogs, and the “fact” that this will cause vitamin A toxicity.

There seems to be a misunderstanding of facts. Since emails regarding the subject are still arriving, let me try to help calm your fears if you’ve been reading the same thing.

Most people can pill their dogs without food. Due to Tori’s neck problem, I’m not one of them. I hide her pills in small bits of cheese, and sometimes in a bit of liver. I am not poisoning my own dog, and I bet you’re not poisoning yours either. Here’s what you need to know: The liver of any animal (chickens, cows, sheep, etc.) is a rich source of vitamin A. True enough, this vitamin can reach a toxic level, but you’d have to try really hard to get there. To give you an example, the NRC shows the recommended allowance for vitamin A (retinol rather than from vegetable sources) for a 10 pound dog to be approximately 156 RE per day. The NRC’s safe upper limit of vitamin A for this same 10 pound dog is 6,534 RE. As you can see, the range between the recommended allowance and safe upper limit is great, but how does this apply in real life? 2-1/4 oz of braised beef liver looks bigger than it sounds. Even so, this amount provides less than the safe upper limit of vitamin A , so our theoretical 10 pound dog would not have vitamin A toxicity. If this dog ate a raw diet, s/he could enjoy a little more beef liver and still not have a problem.

Beef liver does include one big potential problem if overfed. Unfortunately, this was not mentioned in any emails I received, but is what people should be far more concerned with. Beef liver provides a whopping amount of copper. Let’s consider the same 10 pound dog. The NRC recommended allowance for dietary copper is only 0.62 mg per day. 2-1/2 oz of braised beef liver would provide 10 mg of copper. Reality is different for most people. Few if any of us would feed enough beef liver to cause a major problem if we’re feeding it only as a way of hiding pills. However, we can choose chicken liver instead. 3 ½ oz of simmered chicken liver provides 3,978 Retinol (vitamin A) and only 0.496 mg of copper. The same amount of raw chicken liver provides 3,290 Retinol (vitamin A) and 0.492 mg of copper. This is far more than anyone would use as a pill-pocket for a 10 pound dog, and without risk of toxicity.

As an aside, if you're wondering why raw liver provides less vitamin A and copper than the same amount of cooked liver, the answer is in the water content. One ounce of raw liver includes more moisture than cooked liver does. As a result, there is "more liver" in the cooked version, and so, more vitamin A and copper as well.