An “expert” panel of the Association of American Feed Control Officials (AAFCO) refuses to set an upper limit of copper in commercial dog food. This decision was published recently, more than two years after five internationally known liver disease veterinary experts, with 200 years of combined experience, opined that there was too much copper in commercial dog foods.
The AAFCO is a voluntary association of local, state, and federal agencies that operate in a watchdog capacity to regulate the sale and distribution of animal feeds and drug remedies. AAFCO requires a minimum copper content of 7.3 mg/kg/DM (dry matter) in dog food or approximately 1.7 mg/1000 kcals consumed. It has NOT set a maximum limit. The Federal Drug Administration (FDA) and dog food companies look to AFFCO for guidance in setting required dog food contents.
AAFCO formed its “expert” panel in March 2021, a month after the five liver disease experts suggested setting a maximum copper content in dog food diets by using previously published data, clinical observations, and diet changes in dogs with copper toxicosis.
These five liver disease experts published their article in the Journal of American Veterinary Medicine Association in February 2021. https://avmajournals.avma.org/doi/full/10.2460/javma.258.4.357
They noted that AAFCO changed its recommendation regarding the type of copper additive to be used in commercial dog foods in 1997.
Copper oxide had been used in diets before 1997 but then without any evidence of dietary copper deficiency in dogs, the companies switched to copper sulfate because it was absorbed more easily. That’s when the five liver disease experts, in their practices, began to see a sharp increase in the number of dogs of all breeds and mixed breeds that had copper toxicosis (CT) also known as copper-associated hepatitis (CAH), chronic copper-associated hepatitis, and copper-associated liver disease.
The AAFCO panel recently called for in vivo studies (live animal research) before a maximum copper number could be set but failed to explain how these studies would be conducted without harming their dog subjects. https://www.aafco.org/wp-content/uploads/2023/03/Response-from-AAFCO-to-JAVMA-Viewpoint-Article-of-February-15-2021.pdf and https://truthaboutpetfood.com/wp-content/uploads/2023/01/Copper_in_Dog_Foods_Expert_Panel_Report_to_the_PFCkv2136684-2136685.pdf
The panel’s majority rejected a request to only allow copper oxide in dog foods. Some members recommended that the AAFCO Pet Food Committee consider language defining low copper food as containing Cu maximum of 15 mg/kg/DM (dry matter) or more than triple the amount of copper found in Hills and Royal Canin specialty liver diets. But that also was rejected.
Hills advertises its prescription liver diet dog food as approximately 5ppm which equals 5 mg/kg/DM. Royal Canin lists its maximum copper content as 5 kg/mg/DM. Both foods have low protein- 14.5 % listed for Hills and 14% for Royal Canin.
Certain breeds predisposed to CT include Bedlington Terriers, Dalmatians, Doberman Pinchers, Labrador Retrievers, and West Highlands White Terriers. But according to Keith P. Richter, DVM, of the Veterinary Specialty Hospital of San Diego, one member of the expert liver disease group, all breeds and mixes, including “designer dogs,” can have CT which is fatal unless caught early. In these predisposed breeds, he adds, research shows that genetic and environmental factors, including food, contribute to the manifestation of the disease. He says that veterinarians routinely ask the owner of the patient suspected of liver disease what food the dog eats and recommend food with a lower copper content.
AAFCO PANEL
AFFCO panel was to consider the amount of copper in commercial dog food. The original 10-member AFFCO panel included FDA employees, regulatory consultants, a representative of a prominent dog food manufacturing company, consulting firm technical advisors to pet food manufacturers, and employees or researchers of a mineral sciences company. Three members were veterinarians but none appeared to be practicing clinicians as part of a veterinary practice nor with specific expertise in treating liver disease in dogs.
The group met three times before adding three members to its panel: a university professor specializing in animal nutrition, an executive of a pet nutrition consulting firm, and an expert in liver disease nutrition. The thirteen members met in July 2022.
After an extensive review of scientific documents, the panel’s majority concluded “ there was insufficient empirical data to establish a safe upper limit or maximum tolerable level in normal dogs. No additional empirical data has been added to the scientific nutritional literature that bears on what a maximum limit for copper should be in normal dogs since 2006.” The panel noted, “The National Academies Ad Hoc Committee on Dog and Cat Nutrition did not elect to set a maximum Safe Upper Limit (SUL) for Cu content of dog foods when it revised the nutrient requirements for dogs and cats in 2006, stating there was a lack of sufficient data to set such a value.”
Dr. David Twedt, DVM, Professor Emeritus of the Colorado State University’s James L. Voss Veterinary Teaching Hospital notes that recommended maximum amount of copper listed in 2006 by the AAFCO Canine Nutrition Expert Subcommittee “was 250 mg/kg which is an astronomical value and that came from studies done in pigs, not dogs!” Twedt is one of the well-known liver disease experts who opine there is too much copper in commercial dog foods.
The AFFCO subcommittee withdrew that recommendation after the National Academies Ad Hoc committee’s revisions.
Before recently rejecting setting an upper limit of copper in dog food, the AAFCO panel reviewed studies of copper in chickens and pigs; food studies of Labradors conducted over 20 years; and a specific study of copper gluconate fed to beagles over a fairly short time period.
The AFFCO panel noted that the maximum copper in commercial dog food from 2017 to 2021 averaged from 20 to 30 mg/kg DM (dry matter), with the highest amount of 140 mg/kg/DM!
The AFFCO report states “A general rule of thumb among nutritionists is that approximately 10 times the minimum requirement is a maximum dietary content to adhere to if a definitive maximum has not been established and little is known about the concentration causing marginal toxicity.” That would set the maximum allowed copper in adult dog food at 60 mg/kg for adults, 110 mg/kg for puppies, and pregnant and lactating females 124 mg/kg!
Twedt says he believes “it is negligence to use thumb rules that have no scientific basis when it comes to the lives of dogs and their owners.”
The AFFCO panel called for a study to determine the maximum amount of copper that would be safe in dog food but didn’t outline how such a study would be conducted without putting dog subjects at risk. It rejected the European Union’s upper limit of 25 mg/kg/DM.
That limit is way too high, Richter says, adding that at least the EU set a limit, yet that limit was set due to environmental exposure rather than a nutritional upper limit.
LIVER DISEASE EXPERTS’ RESPONSE
Richter said he and his fellow liver disease experts were incredulous, outraged, frustrated, and dismayed by the dismissiveness of the AFFCO’s panel of their work and report. They intend to write a collective response for the American Veterinary Medical Association.
Richter noted that none of the AFFCO “expert” panel specialized in treating or researching liver diseases in canines. He and Twedt are part of a group of liver disease experts that include Sharon A. Center, DVM, James Law Professor Emeritus of Cornell University’s College of Veterinary Medicine; Cynthia Webster, DVM, Professor, and Associate Chair for Research in the Clinical Sciences Department, Cummings School of Veterinary Medicine, Tufts University; Joseph J. Wakshlag, DVM, Ph.D., also of Cornell and a nutrition specialist with expertise in hepatic nutrition; and Penny J. Watson, DVM, Department of Veterinary Medicine, University of Cambridge, United Kingdom. Wakshlag participated in the final AFFCO panel work session but found his opinions to be an outlier in the discussions.
BACKGROUND
Most of these experts were part of a group that wrote the College of Veterinary Internal Medicine 2019 consensus statement about diagnosing and treating chronic hepatitis in dogs. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524396/
All are Diplomates of the American College of Veterinary Internal Medicine (DACVIM) except Watson, who is a member of the European equivalent. Wakshlag also is a Diplomate of the College’s Nutrition specialty.
These veterinarians then formed a group to address the increase in the number of dogs afflicted with CT since 1997 and to try to educate the public and dog food companies as to why dogs must consume less copper than is currently available in most commercial dog food. They published their findings and opinions in the February 2021 issue of the Journal of the American Veterinary Medical Association, suggesting there was too much copper in commercial dog food. See: https://avmajournals.avma.org/doi/full/10.2460/javma.258.4.357
In this article, they mentioned a small study of feral dogs and “purpose-bred” dogs (dogs bred for laboratory use) in Malaysia and Nicaragua. The purpose-bred canines were fed commercial dog food with added copper in the amount of 23 mg/kg DM and the fifteen feral dogs presumably were fed human food scraps and foraged human foods. The amount of copper in the feral dogs’ food was unknown. World-acclaimed liver disease specialist David Twedt along with Allison Bradley and Craig Webb conducted this study in 2012-13.
According to Richter, this study shows that dogs, with very low copper intake, have low copper concentrations in their liver, and remain healthy, suggesting highly absorbable copper such as copper sulfate is unnecessary to add to dog food. He adds that the study shows that dogs with a high intake of copper in their food, also have high copper concentrations in their liver.
Twedt says a recent study of 4559 liver biopsy samples analyzed for copper content over a ten-year period, from 2010 to 2020, shows that half the dogs had increased copper in the liver. CT-affected dogs (canines with abnormal concentrations of hepatic copper greater than 400 micrograms/grams dry weight), included 118 different breeds as well as mixed breed dogs. Certain breeds had abnormally high copper content in their livers: Doberman Pinschers, Labrador Retrievers, West Highland White Terriers, and Dalmatians but also corgis and King Charles Cavalier Spaniels. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9708449/
EXPERTS’ WORK SINCE THEIR 2021 ARTICLE
Since publishing their 2021 article, the liver disease experts surveyed 3,500 veterinarians in part to learn the cost of diagnosing and treating a dog with CT, according to Richter. One-hundred seventy-two board-certified internal medicine specialists responded. The average cost of such diagnosis and treatment is high- more than $8,000 which includes an initial and subsequent liver biopsy, examinations, medications, and low copper food (but not the human cost of travel, time off from work, and emotional wear and tear).
The liver disease experts unsuccessfully approached the FDA about lowering the amount of copper in dog food and a couple of dog food companies about their concerns, according to Richter.
On a more positive note, Richter says that a study is in the final planning stages that is expected to show that there could/should be a lower safe copper limit for normal dogs similar to that used to feed dogs with too much copper in their liver (hepatic diets, such as Hills and Royal Canin diets that contain about 5 mg/kg DM of copper.) That’s an alternative to a study to research an acceptable maximum amount of copper- a study that Richter and his group don’t feel can ethically and practically be performed.
In part, this is true because such a study would need hundreds of dogs: some fed what some consider a safe upper limit and a control group fed much less. These canines would have to be fed over years with periodic biopsies. Richter says that if the predicted safe upper limit is incorrect, many dogs could suffer liver failure.
As the public waits for the study to determine a safe lower limit of copper in dog food, what can canine owners do? The liver disease experts suggest:
- Email their pet food companies to ask about how much copper is in their dog’s food. Be sure to specifically ask for the total amount of copper in mg/kg/DM so you can check the number against the minimum AAFCO number. Remember too much copper can be toxic to your dog’s liver.
- Ask dog food manufacturers to lower the copper content in their food.
- Richter says treats aren’t a real problem if only about 5% of the dog’s diet are treats. If they are 10% or more, check the copper content of the treats, with dried liver being the exception since it can be very high in copper.
- If you supplement your dog with some wet dog food, find out its copper content if, combined with treats, both total 10% or more of your dog’s diet.
These 6 1/2 week old Dalmatian puppies can only make you smile! Their dam is Sadie (GCH CH CT URO-2 UKC CH Monumental Ravenwd Smart Choice CD RE ATD), owned and bred by Tana and BJ Rugg (Tana Rugg photo) - If you feed your dog a homemade diet (cooked or raw), have a board-certified veterinary nutritionist review the diet and make sure it doesn’t contain too much copper but enough protein.
- Check your well water and water pipes if they are copper and you live outside an urban or suburban area.
- Be careful your dog doesn’t drink swimming pool water or devour fertilized grass or preserved wood. All can have significant copper content.
- Feed all dogs food that has a lower rather higher content of copper. Richter notes that some low copper diets tend to also have low protein, which may not be sufficient for all dogs.
- Richter (and others in his group) personally feeds his/ feed their dogs The Scoop diet designed by a veterinarian who lost a dog to CT. The Scoop diet meets AAFCO minimum requirements of copper which comes from all-natural sources and contains no supplemental copper sulfate. https://www.safedogfood.com/
- Educate your veterinarians about CT if they are unfamiliar with the disease.
- For dogs of predisposed breeds to CT, have annual bloodwork done, starting at age two or three, (or even as young as one year of age) to monitor liver enzyme levels that may indicate damage to the liver.
- If possible, feed your dog a diet with no more than Cu 7.5 kg/mg DM and is complete and balanced to meet the nutritional needs of the dog.
- If CT develops in your dog, be sure to report this to the FDA and ask your veterinarian to do the same.
McKinley after a tough day! (Mary Beth Moser photo)
The liver disease experts also suggest consulting with a board-certified veterinary nutritionist to help formulate a diet low in copper. https://www.vetspecialists.com/. Never feed your dog grapes, raisins, onions, or garlic. Specifically, avoid feeding your dog these foods that contain a high amount of copper:
- Organ meats, including liver, heart, kidney, and brain
- Shellfish including oysters, scallops, shrimp, lobster, clams, and crab
- Seeds
- Nuts
- Wheat-bran cereals
- Whole-grain products
- Soy protein meats substitutes, soy beverages and soy wheat/grits
- Tofu
- Mushrooms
- Nectarines
- Commercially dried fruits including raisins, dates, and prunes
- Avocados
- Dry beans including soybeans, lima beans, baked beans, garbanzo beans, and pinto beans
- Dried peas
- Lentils
- Copper-fortified formulas
Stay tuned for more developments on this important topic!
FEATURED PHOTO: Brady (GCH CH CT RBIS UKC CH Monumental Taking The High Road BN RA CAX BCAT) owned by Tana and BJ Rugg, competing at an AKC Coursing Ability event at age 3 1/2 years old. (KC Snaps Photo)
RELATED ARTICLES
https://www.caryunkelbach.com/copper-toxicosis-in-labrador-retrievers-in-united-states-new-research/
https://www.caryunkelbach.com/copper-toxicosis-labrador-retrievers/
Great information Cary. I have to admit though, I loathe it when Veterinarians push to feed Purina, Science Diet etc. Those kibble foods are loaded with stuff I cannot even begin to pronounce! If I can’t pronounce it, it is not going into my dog. I feed a high quality (per dogfoodadvisor.com) commercial raw diet to my four dogs. Again, very informative article, as always.
Thanks for your comments, Sandi. We have been feeding Purina Pro Plan with another food. When I recently checked with Purina, the copper content had gone up from a year ago. Good grief. Time to change food!
This is good info, Cary and I appreciate the detailed research you did with credible sources. Thanks for sharing!
Thanks Cam! The liver disease experts were very helpful!!