Emeritus James Law Professor of Internal Medicine Cornell University Ithaca, NY, United States
Abstract:
Background: Canine risk for liver-copper (Cu) accumulation from commercial diets supplemented with premix-micronutrients remains controversial. There is no maximum Cu-limit for dogs nor informative Cu-labelling requirements. Commercial dog foods (2017-2021 per AAFCO) averaged 20-30 mg Cu/kg dry matter (DM, ≥0.5-0.8 mg Cu/100 kcal assuming 3,200-3,600 kcal/kg DM), exceeding minimal-allowances of 0.15-0.18mg Cu/100 kcal by 3-to-5 fold. Copper-restricted (0.10-0.12 mg Cu/100 kcal) protein-modified prescription liver diets dominate medical management of Portosystemic-Vascular-Anomaly (PSVA) dogs if surgical intervention is not possible.
Objective: As portosystemic-shunting does not alter oral Cu-distribution or organ Cu-accumulation, we sought to validate safety of chronic feeding Cu-restricted diets to medically managed PSVA dogs stratified by dietary Cu intake (Cu-restricted vs Cu-replete [≥0.40mg Cu/100kcal]) and against surgically managed dogs.
Methods: 377 lifetime-surveilled Extrahepatic-PSVA dogs (1980-2015) were categorized by ligation status (complete- or partial-ligation, or medical-management stratified by dietary Cu intake;Table. Details evaluated included: age (diagnosis, death), physical/clinical/hematologic features, death-cause, and survival duration/curves. Statistics: Wilcoxon Rank Sum test, 2-by-2 tables (Fisher Exact Test), and Kaplan Meier (Gehan-Wilcoxon, Log-rank test) interrogated differences with 2-sided P</em>< 0.05.
Results: No coat, neuromuscular, orthopedic, nor hematologic (1-yr sequential CBCs, n=98 Cu-restricted dogs) implicated Cu-insufficiency. Complete-ligation achieved significantly longer survival than partial-ligation or medically-managed dogs. However, survival of medically-managed Cu-restricted dogs did not differ from partially ligated dogs.
Conclusion: Findings validate lifetime-safety of 0.10-0.12mg Cu/100 kcal in E-PSVA dogs. While best survival is achieved with complete shunt attenuation, partial-ligation and medical-management with a Cu-restricted diet are reasonable alternatives.
