Hemopet Interviews Steve Brown

Steve Brown Discusses Vitamin D Toxicity in Pet Foods

For the past few weeks, Hemopet has been trying to understand how toxic levels of vitamin D ended up in pet food. What appeared odd was that these excesses happened with two different types of pet foods – kibbles and canned – that were manufactured in different plants and affected various brands. Indeed, the processing of kibbled and canned foods are completely different from one another. Fortunately, the kibbles were recalled in December 2018 and the canned in February 2019. While many dogs apparently became ill, none of the 6 dogs originally reported to the FDA passed away as a result.

We still need to know why toxic levels of vitamin D were found in pet food. After a thorough search into pet food manufacturing practices, we decided to talk with expert, Steve Brown, who graciously agreed to speak with us.

Steve Brown has led a storied life from working at the Massachusetts Institute of Technologies to creating some of the best known pet food products available. Over 25 years ago, he helped develop the low-calorie Charlee Brown Dog Treats. From there, he proposed products to the pet food industry and was given the opportunity to tour several pet food manufacturing plants. He was dissatisfied by the experience and set off to create Steve’s Real Pet Food, the first commercially available raw dog food.

Since raw dog food was uncharted territory during the 1990’s, Steve applied his researcher skills to develop a raw diet that met the Association of American Feed Control Officials (AAFCO) standards. In doing so, he created a comprehensive pet nutrition database of supplements and food that has information from the United States Department of Agriculture (USDA), AAFCO, European Union pet food standards and other sources. He continued this work for several years, sold it recently to the Animal Diet Formulator, and entered retirement.

First, let’s discuss vitamin D…

Vitamin D is a fat-soluble vitamin just like vitamins A, E and K. They are stored in fatty tissue and in the liver, unlike the water-soluble vitamins B and C, which are flushed out.

The main way vitamin D is produced in the body is when skin is exposed to sunlight. However, even with sunlight, today’s depletion of the ozone layer and industrial haze provide less than the required amounts of direct sun and vitamin D to sustain the body’s needs for optimal health.

Vitamin D helps dogs and cats maintain the appropriate calcium and phosphorus levels in their bodies, which is essential for bone formation, as well as for heart, muscle and nerve function. However, very high amounts of vitamin D can have numerous serious health effects, including kidney and liver disease and even death.

Symptoms of vitamin D poisoning in dogs and cats include vomiting, loss of appetite, increased thirst, increased urination, excessive drooling and weight loss.

What Steve says…

With kibble, most manufacturers assume that the finished product has little or no micronutrient value. So, the manufacturers spray on a premix of vitamins and minerals. Steve says a number of things could happen.

Steve does not know exactly what happened in these recent cases of vitamin D excess, but he has several thoughts:

  1. The minimums and maximums for vitamin D are not that far apart, at least when compared to other nutrients with known maximums. The minimum is 500 IU/kg and the maximum is 3000 IU/kg (AAFCO, dry matter basis). Thus, the maximum is only 6 times the minimum, which does not leave much room for error.
  2.  The intensity of vitamin D within these supplements is much more nutrient-dense than in the supplements you can buy at a store. Commercial manufacturers are very in-tune to palatability issues, and the fillers in these supplements are not tasty ingredients. So, one gram or capsule of most retail vitamin D supplements may have 500 – 5000 IU. One gram of a commercial vitamin D supplement can contain 500,000 IU. A dog can get a toxic amount of vitamin D, if the pre-mix is not blended well, the food manufacturer fails to blend it evenly, adds too much or makes any mistake. In this event, chances are there may be other nutrient excesses, deficiencies or imbalances elsewhere in the batch. We just may not be aware of them.
  3. For example, Steve believes that the pre-mix may have become settled and separated due to uneven mixing or mishandling. When this occurs, the minerals are much denser and fall to the bottom of the vat. The vitamins, on the other hand, end up at the top. So, a dog that eats a meal with a pre-mix from the top of the vat, may ingest an excess of vitamin D and other vitamins.

What about the dogs that receive minerals from the bottom of the vat? This concerns Steve, too. Copper accumulation – also known as copper-storage hepatopathy or toxicosis – is a progressive, slow and chronic condition that can lead to cirrhosis of the liver and liver failure. Some breeds are known to be genetically predisposed to copper storage disease (e.g. West Highland White Terrier, Bedlington Terrier, Skye Terrier, Doberman Pinscher, Labrador Retriever, Keeshond, and American Cocker Spaniel). They should eat even lower amounts of copper (10-14 mg/kg, versus the 18-22 mg/kg often found in current pet diets. Acute or sudden onset of copper toxicosis and liver disease can also happen in young dogs, but is more rare.

In sum, the onset of vitamin D toxicity is rather rapid with severe clinical symptoms, and can lead to death. The less attention-getting ‘sleeper condition’ of concern is the slower progressive accumulation of copper.

What about vitamin D excess in canned pet foods? Steve admits he knows less about the processing of canned foods compared to kibbles. Canned food is ostensibly not as highly cooked as kibble, so the ingredients retain more vitamins, minerals and amino acids. Plus, it is more moisture-rich than kibble. Is the fact that canned foods – or even dehydrated and freeze dried or raw foods – are expected to be more bioavailable taken into consideration during formulation?

Steve said that the majority of pet food formulations – whether it be dehydrated or freeze dried, canned, raw, kibble or home-prepared – do not have enough vitamin D derived from the actual food ingredients. So, they do need an added vitamin D supplement.

This is the same for human foods. Vitamin D is added to several staple human food items as well to make up for the food deficit.

Steve knows a lot and is passionate about vitamin D. In the early 2000’s, his first raw dog food formulation was erroneously and presumptuously claimed to have an excess of vitamin D. He carefully pored over the data and proved that his food, in fact, was just above the bare minimum AAFCO standard for vitamin D.

Overall, Steve says that the pre-mixes of vitamins and minerals have improved greatly since the 1990’s, when vitamin D toxicities were occurring at a greater rate. Still, he would prefer if manufacturers added the vitamins and minerals separately.

Related Conversation

In November 2014, Dr. Karen Becker interviewed Steve and we had a question pertaining to this statement:

“Many board-certified veterinary nutritionists rely on formulation software that uses only USDA data and AAFCO minimums and maximums. But there are problems with the data. Raw kale is an example. USDA data shows copper levels 7 times higher for raw kale than what is actually in it. The USDA reported copper levels in raw kale at 2.9 mg/kg in 2008, but at 14.9 mg/kg in 2013.”

We were wondering if the discrepancy could be due to differences in the soil, the climate, or where the kale was grown.

Steve said, “No, this discrepancy is too high for those variables.” He then showed us a comparison between the various types of processed kale that included added spices as well as frozen kale. They were all in the same range for amounts of copper as in the original data from 2008.

He also demonstrated this for vitamin D. We asked him why these discrepancies exist. He noted that it was the food testing laboratories. Therefore, we need to look more at the average amounts. This is why his database reflects multiple sources beyond just the USDA.

What’s Steve Up to Now?

Steve claims to be retired, but he does not appear to be slowing down when it comes to developing products for optimal pet nutrition! Currently, he is researching the emerging important human and pet health topic of gut microbiota.

Steve believes that while we have gained great insight into feline and canine nutrition, we are also “chasing our tails” in some respects. He believes that dogs are born in environments that are too sterile these days. So, they are not getting exposures to the robust mix of gut bacteria imparted by more natural environments.

His observations come from the many years he bred dogs. He realized he had less health problems with the litters he let “just be puppies”.

So, he is now working on products for the canine gut microbiota and plans to start testing it with dogs on kibble diets in a few months.

This is exciting! We cannot wait to find out the results and to report the findings.

W. Jean Dodds and Hemopet would like to thank Steve! We were honored that he agreed and thank him enormously for his time and insight.


Becker, Karen. “Steve Brown on Optimal Nutrition for Dogs.” Healthy Pets Mercola, 7 Nov. 2014, http://www.healthypets.mercola.com/sites/healthypets/archive/2014/11/07/steve-brown-raw-pet-food-diet.aspx.

Dodds, Jean. “Dietary Modification to Reduce Copper Accumulation.” Hemopet, 10 Feb. 2015, https://drjeandoddspethealthresource.tumblr.com/post/110643792676/copper-accumulation-dogs#.YCFCSuhKjIV.

Home Page. Animal Diet Formulator, http://www.animaldietformulator.com.

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