Hematological and neurological side effects associated with the use of aluminum based phosphate binders in dogs with chronic kidney disease

Hyperphosphatemia and secondary hyperparathyroidism are common in dogs with chronic kidney disease (CKD). It was hypothesized that dogs with CKD managed with aluminum-based phosphate binders accumulate aluminum, and may present clinical signs of toxicity. Fifty two client-owned dogs with CKD were examined in this retrospective study. Dogs diagnosed with CKD that were managed with aluminum based phosphate binders for at least 45 days and had complete blood count available were included, and followed for up 120 days. Blood samples for aluminum concentration were drawn directly into plastic syringes using a newly placed peripheral intravenous catheter. The mean aluminum concentration for dogs was measured to 0.12±0.13 ppm (range, 0.031-0.52 ppm) (reference range < 0.08 ppm). Eighteen dogs were suspected of having aluminum toxicity. The average aluminum daily dose in those dogs was significantly higher compared to dogs for which aluminum toxicity was not suspected (117.4±63.7 vs. 71.5±40.3 mg/kg/day, P = 0.002). Clinical signs suspected to result from aluminum toxicity were ataxia, altered mentation, paraparesis, tetraparesis, and decreased peripheral reflexes, decreased papillary light response and tremor. The most pronounced changes documented in dogs were progressive decrease in mean corpuscular volume and hemoglobin concentration. Both were found as reliable predictors of aluminum accumulation as well as sensitive and specific markers. It was concluded that dogs with CKD accumulate aluminum and are prone to aluminum toxicity. Progressive decrease in MCV and MCH should alert clinicians to aluminum accumulation. Dogs with advanced CKD managed with high aluminum doses should be screened routinely for aluminum accumulation.