Effects of oral versus parenteral cobalamin supplementation on methylmalonic acid and homocysteine concentrations in dogs with chronic enteropathies and low cobalamin concentrations.

The objective of this study was to compare the effects of parenteral (PE) versus oral (PO) cobalamin supplementation on serum methylmalonic acid (MMA) and homocysteine (HCY) concentrations in dogs with hypocobalaminaemia. Thirty-six dogs with serum cobalamin concentrations below 285ng/L (reference interval (RI): 244-959ng/L) were treated with PO (0.25-1.0mg daily) or PE cobalamin (0.25-1.2mg/injection) using a block-randomized schedule. Serum MMA and HCY concentrations were analysed at day 0, 28 and 90 after start of supplementation. There was no significant difference between the PO and PE group regarding serum MMA or HCY concentrations at any time point. Median (range, P comparing baseline and 28 days, P comparing 28days and 90 days) serum MMA concentrations (nmol/L; RI 415-1193) were 932 (566-2468) in the PO and 943 (508-1900) in the PE group at baseline, respectively, 705 (386-1465, P<0.0001) and 696 (377-932, P<0.0001) after 28 days, and 739 (450-1221, P=0.58) and 690 (349-1145, P=0.76) after 90 days. Serum HCY concentrations (median (range), P comparing baseline and 28 days, P comparing 28days and 90 days, μmol/L; RI 5.9-31.9) in the PO and PE groups were 12.2 (3.3-62.2) and 8.4 (3.7-34.8) at baseline, 12.5 (5.0-45.0, P=0.61) and 8.0 (3.8-18.3, P=0.28) after 28 days, and 17.7 (7.3-60.0 P=0.07) and 12.4 (6.3-33.1, P=0.0007) after 90 days, respectively. Oral and parenteral cobalamin supplementation had the same effect on serum MMA concentrations in this group of dogs.