Abstract
BACKGROUND: In humans, absorption and tissue retention rates of intramuscularly administered hydroxocobalamin (OH-Cbl) are superior compared to cyanocobalamin (CN-Cbl). Supplementation with OH-Cbl has not been described in cats. OBJECTIVES: To evaluate effects of parenteral OH-Cbl supplementation on clinical signs, serum Cbl and methylmalonic acid (MMA) concentrations in hypocobalaminemic cats with gastrointestinal disease. ANIMALS: Twenty-three client-owned cats. METHODS: Prospective study. Serum Cbl and MMA concentrations were determined at enrollment (t0), immediately before the 4th OH-Cbl IM injection (300 μg, given q2 weeks) (t1), and 4 weeks after the 4th injection (t2). Severity of clinical signs (activity, appetite, vomiting, diarrhea, body weight) was graded at each time point and expressed as clinical disease activity score. RESULTS: Median clinical disease activity score decreased significantly from t0 (6; range, 2-10) to t1 (1; range, 0-6) and t2 (1; range, 0-9). Median serum Cbl concentration increased significantly from 111 pmol/L (range, 111-218; reference range, 225-1451 pmol/L) at t0 to 1612 pmol/L (range, 526-14 756) (P < .001) at t1, and decreased again significantly to 712 pmol/L (range, 205-4265) (P < .01) at t2. Median baseline serum MMA concentration at t0 (802 nmol/L; range, 238-151 000; reference range, 120-420 nmol/L) decreased significantly (P < .001) to 199 nmol/L (range, 29-478) at t1, and was 205 nmol/L (range, 88-734) at t2. Serum MMA concentrations normalized in 22/23 cats at t1, and were not significantly higher at t2 compared to t1. CONCLUSIONS AND CLINICAL IMPORTANCE: The herein described OH-Cbl injection scheme appears efficacious for normalization of cellular Cbl deficiency in cats with gastrointestinal disease.