Efficacy of intramuscular hydroxocobalamin supplementation in cats with cobalamin deficiency and gastrointestinal disease.

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.

Effects of storage conditions and duration on cobalamin concentration in serum samples from cats and dogs.

OBJECTIVE To evaluate the effects of storage conditions and duration on cobalamin concentration in serum samples from dogs and cats. DESIGN Experiment. SAMPLE Serum samples from 9 client-owned cats and 9 client-owned dogs. PROCEDURES Serum harvested from freshly obtained blood samples was separated into 11 aliquots/animal. One aliquot (baseline sample) was routinely transported in light-protected tubes to the laboratory for cobalamin assay; each of the remaining aliquots was stored in a refrigerator (6°C; n = 5) or at room temperature (20°C) with exposure to daylight (5) for 24, 48, 72, 96, or 120 hours. Aliquots were subsequently wrapped in aluminum foil, frozen (-20°C), and then transported to the laboratory for measurement of cobalamin concentration, all in the same run. Percentage decrease in cobalamin concentration from baseline was analyzed by means of linear mixed modeling. RESULTS No differences in cobalamin values were identified between cats and dogs; therefore, data for both species were analyzed together. Median baseline serum cobalamin concentration was 424 ng/L (range, 178 to 1,880 ng/L). Values for serum samples stored with daylight exposure at room temperature were significantly lower over time than were values for refrigerated samples. Although values for refrigerated samples did not decrease significantly from baseline values over time, values for the other storage condition did; however, the mean percentage decrease for serum samples stored at room temperature was small (0.14%/h; 95% confidence interval, 0.07% to 0.21%/h). CONCLUSIONS AND CLINICAL RELEVANCE Overall, serum cobalamin concentration appeared stable for 5 days when feline and canine serum samples were refrigerated at 6°C. The effect of light and room temperature on serum cobalamin concentration, although significant, was quite small for samples stored with these exposures for the same 5-day period.