The general signs of a vitamin B12 deficiency in the pig are comparable with those observed in other species, principally a loss of appetite, variable feed intake and dramatic growth suppression (Illus. 1). In addition, sometimes there is rough skin and hair coat, vomiting and diarrhea, voice failure, and slight anemia (Catron et al., 1952). Anderson and Hogan (1950) recorded many of these symptoms of vitamin B12 deficiency. Microcytic to normocytic anemia is typical, and many researchers, including Neumann and Johnson (1950), have reported high neutrophil and low lymphocyte counts. However, observations on anemia are not unanimous and are sometimes contradictory. Even observations within one study show a wide variety of effects with regard to hematologic manifestations of vitamin B12 deficiency, as sometimes anemia does not develop at all and at other times moderately severe anemia occurs (Cartwright et al., 1951). Nervous disorders that occur in the pig include increased excitability, unsteady gait (i.e., hind leg incoordination) and posterior incoordination. The thymus and spleen become atrophied, while liver and tongue may be enlarged as a result of proliferation of granulomatous tissue.
