Hypokalemia, muscle weakness, and recumbency in dairy cattle.

Seventeen cases of severe hypokalemia (serum or plasma potassium < or = 2.1 mEq/L) in association with profound muscle weakness and recumbency in lactating dairy cattle were included in a retrospective study. The cattle were from 15 different farms. Eleven of the 17 animals were recumbent at presentation while the remaining six became recumbent within 6 hours of admission. Both multiparous cows (n = 11) and first calf heifers (n = 6) were included. The median days in milk was 21 (range: 5 to 110), and chronic, recurrent ketosis (15 of the 17 cases) was the most common preexistent condition. Potential musculoskeletal and neurologic causes of recumbency were ruled out on the basis of physical examination and ancillary diagnostics. Ten of the 17 animals were euthanized and underwent full necropsy examination that demonstrated ischemic muscle damage and varying degrees of hepatic lipidosis. Aggressive potassium supplementation was instituted in all 17 cases either orally, intravenously, or by a combination of both routes. In the seven individuals that survived, potassium supplementation was administered orally and intravenously in five, orally only in one, and intravenously only in one.