HOW DOG FOODS ARE CAUSING LIVER DISEASE

n 2021, Cornell University circulated a report to veterinarians telling them that pet foods are causing liver damage at an alarming rate.

Here's how AAFCO and pet food makers allowed this problem to happen ... and how you can protect your dog from copper toxicity.

HOW COPPER HARMS DOGS

Copper is an essential trace mineral - which means dogs can't make it and need to get it in their diet. Copper is involved in activating enzymes that pretty much run every metabolic function in the dog's body - plus it helps build red blood cells and grows healthy connective tissue, skin and coats.

When dogs get too much dietary copper (which is called copper toxicity), the copper accumulates in the liver and can cause inflammation and damage. This can scar the liver and, over time, it causes liver failure and even death.

The problem with liver inflammation is that most dog owners have no idea it's happening because dogs don't show symptoms until the damage is really advanced.

The only reliable early sign is changes in the ALT levels. As the liver damage progresses, dog owners might see abdominal swelling, diarrhea, loss of appetite, jaundice, increased thirst and vomiting. But by that time, the damage is fairly serious.

In a nutshell, liver disease is a hidden disease that typically goes unnoticed until it's too late. Even if your dog's ALT levels are high, vets rarely consider copper toxicity as a cause.

COPPER LEVELS RISING IN DOG FOODS

Back in 1929, researchers looked at how much copper was stored in the dog's liver. On average, they found about 10 ug/g. In 1982, the average rose to a massive 200 ug/g ... and in 1995, copper levels were up to 453 ug/g. So the amount of copper in the average dog's liver doubled in just 13 years and continues to rise.

As a result, dogs today are walking around with livers that are equivalent to those of alcoholics.

HOW MANY DOGS ARE AFFECTED?

One of the authors of the Cornell study found that 58% of liver biopsies showed signs of inflammatory liver disease and averaged more than 400 ug/g copper concentration.

So it's estimated that more than half of dogs could be affected by excess copper.

HOW IS COPPER GETTING INTO DOGS?

When researchers looked into the issue of copper toxicity, they first looked for breed-specific diseases. But that wasn't the cause. In fact, the amount of copper in dogs' livers was directly related to the amount in their diet.

This was a surprise since all of the foods met the Association of American Feed Control Officials (AAFCO) nutritional requirements.

AAFCO sets nutrient guidelines for pet food manufacturers - but in most cases, AAFCO nutritional requirements are based on minimum amounts only. They look at the minimum amount a dog needs to get by without overt signs of disease.

When it comes to most nutrients, AAFCO has not set a maximum allowable amount. And this is the case with copper.

The minimum copper requirement for adult dogs is 7.3 mg/kg but dog food makers are free to put as much copper in the food as they want - as long as they meet the minimum requirement.

WHY IS COPPER ON THE RISE?

Why are pet food manufacturers putting so much copper in their food? And why is there more and more every year? There are a number of reasons for this ...

Many of the nutrients in pet foods are lost in the heating and processing. Foods can suffer a 40% loss in copper (as well as other nutrients). To compensate for this, pet food manufacturers add something called a premix to their foods.

A premix is a bag of vitamins and minerals that is intended to either replace the nutrients that are lost during processing or add them to foods with low quality ingredients. These premixes contain an assortment of vitamins and minerals and the mix is usually just added to dog foods – often in excess since AAFCO is mainly concerned about minimum nutrition requirements.

To compound this issue, most premixes used an inorganic form of copper (copper oxide). But 15 years ago, AAFCO worried about this because copper oxide has terrible bioavailability in dogs.

At the time, there were no reports of copper deficiency in dogs – and the amounts of copper were already rising in dogs' livers. Despite this, AAFCO recommended a much more bioavailable form of copper be used in pet foods –like copper sulfate. They did this without any peer-reviewed studies or re-evaluating the minimum requirements.

Since then, dog foods contain even more bioavailable organic forms of copper like copper chelate – especially the premium brands since these forms of copper are more expensive.

To make matters worse, a lot of dog foods today are adding foods that are innately rich in copper. The worst offender is liver – but copper is also naturally rich in fish and seafood, chickpeas and sweet potatoes.

HOW DO YOU FIND EXCESS COPPER?

Pet foods aren't required to report the amount of copper on pet food labels. So if you're worried about copper toxicity (and you should be), then you need to ask your manufacturer for a nutritional analysis that shows the amount of copper in their food.

If they don't give it to you, then just keep asking until you find a manufacturer that will tell you the amount of copper in their food. Ideally, the copper shouldn't be too much higher than AAFCO's recommended minimum, which is 7.3 mg/kg for adult dogs and 12.4 mg/kg for puppies.

There are some dog foods that are low in copper, but they're often low in protein too so they're not a good choice.

Dana Scott