Effects of lithium carbonate administration to healthy cats

Lithium carbonate administration to healthy cats was evaluated in 2 controlled studies (a dose-response study and a bone marrow evaluation study) to determine the effectiveness of lithium as a bone marrow stimulant. Lithium carbonate was administrated at dosage ranging from 300 to 1,050 mg/m2 of body surface/d. Complete blood count, serum lithium concentration determination, serum biochemical analysis, urinalysis, and bone marrow aspiration and biopsy were periodically performed. Serum lithium concentration greater than 2 mEq/L was associated with significant decrease in numbers of circulating segmented neutrophils (less than 1,200 cells/microliter; P less than 0.01) and lymphocytes (less than 1,300 cells/microliter; P less than 0.0001), as well as significant (P less than 0.05) decrease in urine specific gravity. Bone marrow evaluation revealed apparent maturation arrest of the neutrophil cell line. Coincident with the changes in laboratory values, the lithium-treated cats became ill. Changes in behavior and vocalization were seen, followed by anorexia, vomiting, and diarrhea. In later stages of intoxication, cats became hyperexcitable and manifested coarse muscular tremors. It was concluded that lithium carbonate does not have potential value as a bone marrow stimulant and is toxic to cats at serum concentration greater than 2 mEq/L.