New canine copper assays could support less invasive liver workups

A new American Journal of Veterinary Research paper reports that serum exchangeable copper concentration and 3-kDa ultrafiltered urinary copper measurements have now been successfully adapted and partially validated in dogs, laying the analytical groundwork for possible noninvasive biomarkers in copper-associated hepatitis. That matters because canine copper-associated hepatitis remains a disease where clinicians often need liver biopsy and copper quantification to get diagnostic confidence, especially when routine bloodwork and clinical signs are nonspecific. (academic.oup.com)

The backdrop is a growing clinical focus on copper-related liver disease in dogs. Consensus guidance and later reviews describe copper-associated hepatitis as an increasingly recognized cause of chronic liver disease, linked to both genetic susceptibility and environmental exposure, including dietary copper intake. Predisposed breeds include Bedlington terriers, Dobermanns, Labrador retrievers, Cavalier King Charles spaniels, West Highland White terriers, and Dalmatians, although the problem isn't limited to those groups. (academic.oup.com)

That diagnostic burden is one reason biomarker development has drawn attention. Current standards still emphasize histologic evidence of chronic hepatitis, copper staining, and hepatic copper quantification, often with concentrations above 1,000 μg/g dry weight liver supporting the diagnosis, while also acknowledging a gray zone around 600 to 1,000 μg/g and substantial lobe-to-lobe variability. In practice, that means a noninvasive blood or urine test could be useful not because biopsy is obsolete, but because biopsy is invasive, imperfectly sampled, and not always easy for pet parents to pursue. (academic.oup.com)

The new AJVR study focused on whether the assays themselves could be made to work accurately and precisely in canine samples. According to the abstract provided and related work from the same investigators, the goal was to establish the analytical basis for studying relative exchangeable copper and urinary small copper carrier-to-creatinine ratio as candidate biomarkers in dogs with copper-associated hepatitis. At the 2025 ACVIM Forum, the Texas A&M-led group reported retrospective cross-sectional data from 16 dogs with copper-associated hepatitis, 8 with idiopathic chronic hepatitis, 18 with congenital portosystemic shunt, and 55 healthy controls. Exchangeable copper was measured after EDTA incubation and ultracentrifugation, and urine copper was measured in 3-kDa ultrafiltrates with ICP-MS normalization to creatinine. (academic.oup.com)

Those early clinical signals were encouraging, but mixed. Relative exchangeable copper was higher in dogs with copper-associated hepatitis than in healthy controls. The ultrafiltered urine copper-to-creatinine ratio was higher in dogs with copper-associated hepatitis and idiopathic chronic hepatitis than in healthy controls, and also higher than in dogs with congenital portosystemic shunts. But the reported ROC performance for distinguishing copper-associated hepatitis from idiopathic chronic hepatitis was modest, with AUCs of 0.59 for relative exchangeable copper and 0.61 for the ultrafiltered urine copper-to-creatinine ratio. In other words, these markers may detect liver disease-related copper handling abnormalities, but they aren't yet proven to sort copper-associated hepatitis cleanly from other inflammatory liver disease. (academic.oup.com)

The broader scientific rationale comes partly from comparative work with Wilson disease in people and rodent models. Reviews note that relative exchangeable copper is a promising biomarker in human Wilson disease, and experimental work has identified a small copper carrier in dogs as well as in mice, supporting the biologic plausibility of adapting similar measurements for canine hepatology. At the same time, species differences in copper transport proteins could limit direct translation, which is exactly why analytical adaptation and canine-specific validation are important. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, this is best viewed as infrastructure for better diagnostics rather than a practice-changing test, at least for now. Copper-associated hepatitis is common enough, clinically important enough, and difficult enough to diagnose that even an adjunctive noninvasive marker would be useful. Earlier triage could help identify which dogs need biopsy sooner, support screening in at-risk breeds, or eventually offer a way to follow response to chelation or diet with less reliance on repeat invasive sampling. That said, the available clinical data suggest the assays may be better at distinguishing affected dogs from healthy controls than at separating copper-associated hepatitis from idiopathic chronic hepatitis, which is the harder and more clinically relevant question. (academic.oup.com)

There is also a wider industry context. Recent publications continue to highlight concern about rising hepatic copper concentrations in dogs over time and the possible role of dietary copper exposure, while newer work suggests dogs fed copper-restricted diets have lower liver copper accumulation risk than dogs fed copper-replete diets. If noninvasive biomarkers become robust enough for practice use, they could eventually shape how clinicians monitor dogs in high-risk populations and how researchers study diet, genetics, and treatment response. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next step is full clinical validation: larger prospective cohorts, better assessment of sensitivity and specificity across liver disease subtypes, and evidence that these assays track treatment response or predict biopsy findings. It will also be worth watching whether Texas A&M or other diagnostic laboratories move from research-stage methods to standardized clinical offerings, because that transition will determine how quickly this work reaches day-to-day practice. (vetmed.tamu.edu)