Experimental Production of Nutritional Macrocytic Anemia in Swine : V. Hematologic Manifestations of a Combined Deficiency of Vitamin B₁₂ and Pteroylglutamic Acid

A total of 20 swine were fed a diet adequate in all known respects except that soybean protein was substituted for casein, succinylsulfathiazole and a folic acid antagonist were added, and vitamin B₁₂ and pteroylglutamic acid were withheld from the vitamin supplement.

The animals developed macrocytic anemia, leukopenia and neutropenia, accompanied by erythroid hyperplasia of the bone marrow. Tue erythroblasts consisted mainly of immature macronormoblasts but a few atypical megaloblasts were also observed.

The anemia responded rapidly and completely to the administration of both vitamin B₁₂ and pteroylglutamic acid. The administration of pteroylglutamic acid alone resulted in an immediate return of the blood and bone marrow to within normal limits but after several months there was a partial hematologic relapse in spite of continued therapy with this vitamin. The administration of vitamin B₁₂ alone resulted in only partial remission of the anemia and the bone marrow remained macronormoblastic although the megaloblasts tended to disappear.

Growth of the animals was stimulated by the administration of either vitamin but the administration of both vitamins simultanseously resulted in the greatest rate of growth.

No manifestations of neurologic disturbances or of inscreased pigment excretion were observed in the deficient swine.