Recently, AAFCO (Association of American Feed Control Officials), the group that sets nutritional standards for pet food, considered allowing a “controlled copper” claim on dog food labels based on evidence of increasing copper toxicity problems in dogs.

This proposal began because  veterinarians noticed that more and more dogs were developing copper toxicity. Now, certain dog breeds are genetically prone to copper storage disease: Bedlington Terriers but also West Highland White and Skye Terriers, Doberman Pinschers, Labrador Retrievers, Keeshonds, American Cocker Spaniels, Dalmations, Corgis, and Anatolian Shepherds. Excess copper accumulation in the liver can cause severe inflammation, anemia, liver failure, and death. Dogs with this genetic condition must eat a special, low-copper diet such as those made by Hill’s and Royal Canin.

But these new cases of copper-associated liver disease were not happening in predisposed breeds–they were occurring in normal, healthy dogs eating ordinary commercial dog food.

Multiple researchers, including Dr. Sharon Center at Cornell, put 2 + 2 together. Changes had been made in the nutrient requirements for copper, and the safe upper limit for copper had been eliminated. They discovered that copper levels in dog food were rising over the years, and, surprise! Copper level in healthy pets’ livers also increased. In some cases, the increase was severe enough to cause copper hepathopathy (liver disease) just like those genetically predisposed dogs.

Responding to the alarm raised by these scientists, AAFCO and FDA put together a working group to look into the issue. I was invited by FDA to be in that group. The proposal being considered was to allow language on pet food labels for manufacturers who were willing to limit the amount of copper in their foods to the normal minimum, but not in great excess.

Language was proposed for addition to the AAFCO Official Publication for a “controlled copper” claim. But the committee meetings were contentious. The scientists in the group (including myself) were in favor of this addition, but the group included individuals representing the interests of the pet food industry, and they were completely against it. Now, why would that be? Why would the pet food industry be against something that could save dogs lives? The proposed language was fairly inocuous. But industry was concerned that companies who chose to use a “controlled copper” claim would have a competitive advantage. So they made up all kinds of excuses that really weren’t true, but they were plenty  loud about it.

The proposed language did win in the working group on a “party line vote” (science vs. profit), but when it got to the full AAFCO committee, the science proponents were rational and reasonable and the industry reps were loud, obnoxious, and not at all hesitant to promote their irrational, exaggerated “concerns.” So naturally the proposal failed.  It turns out that the history of copper in dog food is a “series of unfortunate events” that is harming our pets in the name of profit.

I thought that you might be interested to see what goes on behind the scenes and how the pet food industry is completely profit motivated and absolutely uninterested in the health of our pets.

  • It was AAFCO that created the copper issue in the first place. Now that we are seeing the results of AAFCO’s actions, it is logical that AAFCO should take steps to mitigate them. This is entirely appropriate for AAFCO, as one of its primary roles is consumer protection.
  • A single 1993 paper comparing copper oxide and copper sulfate suggested that copper oxide is not sufficiently bioavailable to be used as a copper source in pet foods. AAFCO relied on this one paper—which was not peer-reviewed, not replicated, and did not cite a single case of clinical deficiency in any dog anywhere—to change its 1997 Nutrient Profiles to require copper sulfates or chelates to be used as copper sources in pet food. [Czarnecki-Maulden et al. 1993]
  • The 2006 NRC Dog and Cat Nutrition Requirements failed to set a Safe Upper Limit (SUL) due to insufficient data. In 2007, the AAFCO Canine Nutrition Expert Subcommittee—without any evidence that AAFCO’s published copper maximum was inappropriate—eliminated the maximum in its Nutrient Profiles. 
  • The Expert Committee (a group of nutritionists who looked at the copper issue) cited 23 papers, 11 of which were more than 10 years old. More recent papers show that the problem is bad and getting worse. Contrary to what was stated in one of our meetings, there have been numerous case reports of non-predisposed dogs developing CuAH/CAH. Additionally, several papers suggest that excessive copper in pet food is a broader issue than has yet been considered. (See References below.)
  • Excessive copper levels may be a contributing factor in idiopathic epilepsy [Rosendahl 2023].
  • There is evidence that increased copper levels may also be affecting cats [Yamkate et al. 2022] and ferrets [Richard et al. 2022].
  • Liver copper levels have risen ever since the change to copper sources in 1997. According to Strickland, et al. (2018), “While causation cannot be determined, the close temporal association of changes in [Cu]H with changes in AAFCO copper supplementation recommendations are concerning.” These changes are occurring both in pre-disposed and non-predisposed breeds.
  • These concerns are not limited to “a small group of veterinarians.” I was recently talking with a colleague who owns a clinic in a suburb of Denver. I asked what she knew about copper in dogs. She had not read any of the articles about it so was unaware of the controversy. However, she has had recently seen several cases of dogs with persistent, unexplained elevations of ALT that were subsequently diagnosed by a specialist with CuAH. If average veterinarians in average practices are seeing these cases, the problem is likely quite significant. 
  • The ACVIM (American College of Veterinary Internal Medicine), with its 3,000 members, has expressed concern “that [t]here is strong case-based evidence that current dietary copper allowances for canine diets have caused increased hepatic copper concentrations in pet dogs of mixed or pure breed ancestry. This concern has been amply documented in peer-reviewed veterinary literature. While ACVIM has not reached a consensus on what action should be taken, has expressed a desire “to raise awareness to facilitate early diagnosis and treatment of canine CuAH.” That is precisely what the proposed change to the OP will accomplish.
  • The allegation (made by the industry reps) that AAFCO is getting into marketing is frankly ridiculous. This is not a marketing issue; it is a safety issue. Previous examples include taurine, “lite/light/low calorie,” urine pH, etc. – all of which have profound implications for pet health.
  • The copper in mineral premixes is added on top of the natural copper content of ingredients. Many producers have moved away from “by-products” and use more livers and kidneys; these organs are particularly high in copper. This, of course, provides an even larger safety margin for “controlled copper” in dog foods. 
  • In terms of liability, if there is such a possibility (again, an imaginary reason suggested by the industry reps), I would think there would also be liability for those who are actively fighting against this change. We are talking about a simple, easy-to-understand declaration for consumers concerned about their dogs, to help them make an appropriate choice. Opposition to this change goes directly against AAFCO’s primary mission, as shown above.
  • AAFCO regulators and industry representatives have been working very hard for years to implement the Pet Food Label Modernization (PFLM) project. Isn’t this issue exactly what PFLM is about? Giving consumers more information, more transparency, so they can make better choices?
  • Eventually the premix makers, manufacturers, feed formulation programs will come to the same conclusion: that they ought to reduce copper in their foods. They will quietly make changes in their recipes. But how many dogs will suffer over the next decade or two while that happens? Liver inflammation is painful. Ascites is painful. Losing a beloved pet is painful. How can we justify withholding this relevant information? 
  • Of course, this issue needs more research (the pet food reps were very alarmist about this). Scientific knowledge is expanded and refined every day. Nobody knows everything about pet nutritional needs, but we’re learning. And we have more than enough information now to make this simple change. 

There really is no excuse for the vast overages of copper (and other minerals) in many pet foods.  The current minimum copper for growth is 12.4 mg/kg DM, and for adult maintenance 7.3 mg/kg DM. Some foods have tested well over 10 times that level between 2015-2020, according to the Expert Committee report. 

In one of our working group meetings, I mentioned that pet foods had routinely tested at 300-400% of their minimum requirements. I was challenged on this. But tests of wet and dry dog and cat foods performed by the Kentucky Department of Agriculture in 1994-1995 showed that copper was at 300% or more in well over 40% of dog foods. Note that this was while copper oxide was still in use—clearly, ingredients alone were providing sufficient copper in the vast majority of foods. Less than 5% of products failed to meet 100% of the minimum requirement.  

        Food Tested Cu > 300% of AAFCO min.
Dry adult dog foods  41.4%
Growth dry dog foods  58.8%
Canned adult dog foods  43.1%
Growth canned dog foods  48.3%

 

The same was true of other minerals like iron, zinc, and particularly manganese, which exceeded 450% of the AAFCO minimum in more than 90% of dog foods.

I have seen no evidence that this habit of vastly over-supplementing minerals has changed since then. In fact, the evidence suggests that this practice is ongoing. 

 

References

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