Sharon A. Center, BS, DVM, DACVIM (SAIM): No financial relationships to disclose
Background: Canine risk for liver-copper (Cu) accumulation from commercial diets over-formulated with micronutrient premixes, remains controversial. Regulatory agencies express concern that specialty center studies may not reflect pet dog demographics.
Objective: Investigate 1) liver-Cu concentration in end-of-life liver samples from humanely euthanized dogs in a primary-care-hospital and 2) relationship between liver-Cu and dietary-Cu intake.
Methods: Liver samples from 104-dogs euthanized for geriatric-health concerns (owner consent) in a large primary-care-hospital. Medical records, dietary history, and regional water analyses were acquired. Dietary-Cu (mg/100 kcal) was derived from manufacturers or validated inductively-coupled-plasma-atomic-emission-spectrometry (ICP-AES) in a USDA-micronutrient-laboratory. Liver samples underwent histologic evaluation (H&E, Masson’s trichrome, rhodanine), rhodanine Cu-scoring, and Cu-quantification (µg/g dry-weight-liver [dwl]). Non-parametric statistics defined significant differences (two-tailed P<0.05). Results: 52-male, 52-female, 34-breeds and 22-mixed-breeds, had median (95% CI) age, weight, and diet-duration of 11.9 (10.9-12.3) years; 22.1(18.8-24.5) kg, and 8.0 (7.1-8.8) years. No dog fed 0.15-0.24 mg Cu/100 kcal (low-Cu-diets) displayed evidence of Cu- insufficiency. Water-Cu was 0.12(0.08-0.17) ppm. Common histologic features included: glycogen-type-vacuolation (n=61), reactive-hepatitis (n=20), and neoplasia (n=18). No histologic findings associated with liver-Cu. Thirteen low-Cu-diet dogs had significantly lower liver-Cu than 91-dogs fed higher Cu-intakes (0.31-0.39 and ≥0.40 mg Cu/100 kcal; Graph). Low-Cu-diet dogs did not accumulate >355µg Cu/g dwl whereas in higher Cu-diet dogs, liver-Cu >400µg Cu/g dwl (upper-reference-range) occurred in 20/91 (22%) and >600µg Cu/g dwl in14/91 (15%).
Conclusion: Findings demonstrate significant liver-Cu accumulation with dietary intake ≥0.30 mg Cu/100 kcal vs ≤0.24 mg Cu/100 kcal and exonerate water as a source of Cu loading.
