Safety and efficacy of a ribose-cysteine supplement to increase erythrocyte glutathione concentration in healthy dogs

OBJECTIVE To evaluate the safety of oral administration of a D-ribose-L-cysteine (RibCys) supplement to dogs and the effect of this supplementation on erythrocyte glutathione (GSH) concentration. ANIMALS 24 healthy adult dogs. PROCEDURES In a randomized, double-blinded, controlled trial, dogs received 500 mg of a RibCys supplement or placebo (n = 12/group), PO, every 12 hours for 4 weeks. Dogs were evaluated weekly by means of a physical examination, CBC, serum biochemical analysis, urinalysis, and owner-completed quality-of-life questionnaire. Erythrocyte GSH concentration was measured on day 0 (ie, the day before treatment began) and weekly during supplementation. RESULTS No dose-limiting adverse effects were noted in any dog. Two dogs in each group had mild, self-limiting diarrhea and anemia. No significant increase in erythrocyte GSH concentration was noted in either group at any time point. Two dogs in the RibCys group had improved skin and coat health and improved clinical signs of osteoarthritis. No clinical or owner-perceived improvements were noted in the placebo group. CONCLUSIONS AND CLINICAL RELEVANCE The RibCys supplement was safe and well tolerated in all dogs. Owners reported improvements in dermatologic and orthopedic conditions in some dogs in the RibCys group. No significant differences were observed in erythrocyte GSH concentration before or after RibCys treatment. This lack of significant differences may have been attributable to the use of healthy dogs, which would not be expected to have depleted GSH concentrations. Given the observed safety profile of RibCys, additional research is warranted to explore the potential usefulness of RibCys supplementation in dogs with cancer and those undergoing treatment for cancer.

Automated summary

The study evaluated the safety of RibCys supplementation in dogs and its effect on erythrocyte glutathione concentration. The supplement was found to be safe and well tolerated in all dogs, with some improvements in dermatologic and orthopedic conditions observed in some dogs. However, no significant increase in GSH concentration was noted in either group.