Copper Toxicosis and ALT on Your Embark Report: What These Results Actually Mean

Three results have started appearing on poodle DNA panels that are causing more confusion than almost anything else on the report:

• Copper Toxicosis (Accumulating), ATP7B
• Copper Toxicosis (Attenuating), ATP7A or RETN
• ALT Activity

Breeders are seeing these, reading the word "toxicosis," and reaching for conclusions the results do not support. Here is what each one is, what it is not, and what it means for a poodle specifically.

The headline: two of these three are not diseases at all, and the third was characterised in a breed that is not yours.

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Start here: these variants come from Labradors and Dobermans

Copper toxicosis was characterised in the Labrador Retriever, with the variant subsequently associated with the Doberman Pinscher as well. The foundational work identified two genes that counteract each other in copper handling (Fieten et al., 2016).

Embark states plainly that the risk of the ATP7B variant in breeds other than the Labrador and Doberman is currently unclear.

That sentence deserves more weight than it usually gets. A commercial panel will report a variant in any dog that carries it, because the test detects DNA and DNA does not care what breed it is in. But detecting a variant in a poodle is not the same as demonstrating that it causes disease in poodles.

This is a general principle worth internalising, because it applies to a growing number of panel results as testing companies expand their menus: a test offered for your breed is not evidence that the variant has been validated in your breed.

There is no established poodle-specific evidence for copper toxicosis risk from these variants. That is the honest position, and it is neither reassurance nor alarm. It is a statement about what is not known.

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Copper Toxicosis (Accumulating): ATP7B

This is the one that carries risk.

What it does. Copper is an essential trace element, but the liver has to be able to excrete the excess. The ATP7B variant impairs that excretion, so copper accumulates in liver tissue. Left unchecked over years, that accumulation can progress to liver damage and eventually liver failure.

How it is inherited. Incomplete dominance. One copy is enough to matter, and two copies carry greater risk than one. This is not a carrier-and-clear recessive, and thinking about it that way will mislead you.

When it shows up. Adult onset, typically between two and seven years. Females appear to be more affected than males.

What it is not. It is not a diagnosis. Some dogs with one or two copies never develop copper toxicosis at all. Diet and other environmental factors contribute substantially, and a genotype is not a prophecy.

How it is actually diagnosed. Liver biopsy with copper quantification. Not a DNA test, and, as we are about to see, not a blood test either.

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Copper Toxicosis (Attenuating): ATP7A and RETN

Here is where most of the confusion sits, and it is the easiest thing on this page to fix.

These are the good ones.

ATP7A and RETN are attenuating variants. They reduce copper accumulation in dogs that also carry the accumulating ATP7B variant. They are protective, not harmful.

Read that again if your report showed one, because breeders are looking at the words "copper toxicosis" next to their dog's name and drawing exactly the wrong conclusion.

Three things follow:

1. On their own, these variants are not associated with any disease. A dog carrying ATP7A or RETN with no copies of ATP7B has nothing to think about here. Copper levels will not drop low enough to pose a health risk.
2. They only become relevant in a dog that also carries ATP7B. They modify that dog's risk downward.
3. They are not completely protective. They shift the odds. They do not cancel the accumulating variant.

ATP7A is X-linked and its effect depends on sex: it is most beneficial in males with one copy, while females with one copy likely benefit less than females with two. RETN has complex inheritance and may reduce accumulation and severity in dogs carrying ATP7B.

Do not remove a dog from your programme for carrying an attenuating variant. It is a favourable result.

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The ALT Activity variant, and why it matters more than it looks

ALT, alanine aminotransferase, is a liver enzyme measured on routine bloodwork. When liver cells are damaged, ALT leaks into the blood, so an elevated ALT is one of the standard signals that something is wrong with the liver.

The ALT activity variant means a dog's baseline ALT sits naturally lower than average. It is not a disease. It is not liver damage. It is a normal-variation trait.

But it has a consequence that matters clinically, and this is the part breeders should carry away from this article: if a dog's baseline is naturally low, a result inside the "normal" reference range may not be normal for that dog. A rise that would have flagged as abnormal in another dog can land comfortably within range and go unnoticed.

The variant does not damage the liver. It degrades your ability to detect damage using a single ALT value.

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The finding that ties all three together

This is the most important paragraph on this page.

In a study of Labrador Retrievers and Labrador crosses, dogs homozygous for the ATP7B variant had a mean hepatic copper concentration of 1464 ppm against a reference range of 100 to 330 ppm.

Their serum ALT was normal. None of them had elevated ALT activity.

So: dogs with roughly four to five times the reference concentration of copper in their livers, and bloodwork that looked fine.

A normal ALT does not rule out copper accumulation. That is true for any dog. Now consider a dog that carries both the ATP7B accumulating variant and the low-ALT variant, and you have a dog in which the standard screening test is compromised twice over.

That combination is worth knowing about, and it is the single practical reason to pay attention to these results at all.

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What to actually do

If your dog has no ATP7B copies: the attenuating results are irrelevant to it. Nothing to act on.

If your dog has one or two ATP7B copies: this is a conversation with your veterinarian, not a breeding decision made from a report. Discuss whether monitoring is warranted, and be aware that dietary copper is a genuine contributor. Ask specifically about the limits of ALT as a screening tool for this dog.

If your dog has the ALT variant: tell your veterinarian, and make sure it goes in the record. The value of knowing is that it changes how a future blood panel should be read. Establishing that dog's own baseline while it is healthy is worth more than any single later reading.

For breeding decisions: remember where the evidence comes from. These variants are established in Labradors and Dobermans. Their significance in poodles is not established. Do not remove poodles from a breeding programme on the strength of a variant whose relevance to this breed has not been demonstrated, particularly not an attenuating variant, which is favourable, or an ALT variant, which is not a disease.

Even in the breeds where these variants are established, the guidance is not elimination. Because ATP7B sits at high frequency in Labrador and Doberman populations, it likely cannot be removed entirely, and the recommendation is to breed affected dogs to clear dogs rather than to exclude them. The same logic that applies there applies with more force here, where the relevance is unproven.

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The general lesson

Panels are getting longer. Every year, testing companies add variants, and every year breeders receive results for conditions characterised in breeds they have never owned.

The question to ask of any new line on a report is not "does my dog have it." It is:

Which breed was this variant established in, and has anyone demonstrated that it means the same thing in mine?

For copper toxicosis in poodles, the answer today is no. That may change. Until it does, the honest position is that the result is information, not instruction.

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This article summarises material developed in Appendix C of Poodle Health & Structural Genetics: The Science Behind Form, Function and Disease (Volume III of the Poodle Genetics series). It is educational and is not veterinary advice. Discuss any result on your dog's report with your veterinarian.