926 Scientific Reports JAVMA, Vol 234, No. 7, April 1, 2009 RUMINANTS N eonatal calf diarrhea remains a common and im- portant cause of morbidity and death in unweaned dairy calves in the United States. 1 Diarrhea in calves can lead to dehydration, acidemia, hyperkalemia, and impaired cardiovascular and renal function. 2,3 Oral re- hydration therapy provides a practical and inexpensive method for treating mild to moderate acidemia, strong ion acidosis, and dehydration in neonatal ruminants that have a suckle reflex. 4–6 The ideal ORT solution should contain multiple agents (eg, glucose, acetate, propio- nate, and glycine) that facilitate intestinal absorption of sodium and water, induce systemic alkalinization, do not inhibit milk clotting in the abomasum, are high in energy (with multiple sources of energy such as glucose, acetate, propionate, and amino acids), and have an appropriate glucose-to-sodium ratio between 3:1 and 1:1. 5 Efficacy of oral rehydration therapy solutions containing sodium bicarbonate or sodium acetate for treatment of calves with naturally acquired diarrhea, moderate dehydration, and strong ion acidosis Ismail Sen, Dr vet med, PhD; Vahdettin Altunok, PhD; Mahmut Ok, PhD; Alparslan Coskun; Peter D. Constable, BVSc, PhD, DACVIM Objective—To determine and compare the effects of 4 oral replacement therapy (ORT) solutions on acid-base balance, abomasal emptying rate, and plasma volume expansion in calves with naturally acquired diarrhea and moderate dehydration. Design—Prospective study. Animals—20 calves. Procedures—20 calves up to 45 days of age were randomly allocated (n = 5/group) to receive 2 L of 1 of 4 treatments via oroesophageal intubation: sodium bicarbonate (150 mmol/L or 300 mmol/L) or sodium acetate (150 mmol/L or 300 mmol/L). The 4 test solu- tions contained acetaminophen (50 mg/kg [22.7 mg/lb]) and 50 g of glucose monohydrate. Jugular venous blood samples were obtained periodically before and after administration of the ORT solution. Abomasal emptying rate was determined by use of the time to maximal plasma acetaminophen concentration. Results—Plasma bicarbonate concentration increased more rapidly in calves administered bicarbonate-containing ORT solutions, whereas the rate of systemic alkalinization, as as- sessed via blood pH, did not differ consistently among treatments. The 300 mmol/L ORT solutions were emptied at a significantly slower rate from the abomasum than 150 mmol/L ORT solutions, with no difference in emptying rate between acetate and bicarbonate-con- taining ORT solutions of similar molality. The 300 mmol/L sodium acetate ORT solution significantly increased plasma volume. Conclusions and Clinical Relevance—Clinically important differences in the resuscitative response to 300 mmol/L or 150 mmol/L ORT solutions of sodium acetate or sodium bicarbonate were not identified. (J Am Vet Med Assoc 2009;234:926–934) Acidemia in diarrheic calves results from strong ion acidosis in response to hyponatremia, normochlo- remia to hyperchloremia, and hyper D-lactatemia and nonvolatile buffer ion acidosis that occurs in response to increased plasma protein concentration. 2,7–9 Acide- mic calves with diarrhea should therefore be treated with an ORT solution containing sodium and a high effective strong ion difference, 6,7 although there is de- bate about whether bicarbonate, acetate, propionate, or citrate is the preferred alkalinizing agent. 7 Acetate, From the Departments of Internal Medicine (Sen, Ok, Coskun) and Biochemistry (Altunok), Faculty of Veterinary Medicine, University of Selcuk, Konya, 42079, Turkey; and the Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907 (Constable). Supported by a grant from The Scientific and Technical Research Council of Turkey. Address correspondence to Dr. Sen. ABBREVIATIONS AG Anion gap C max Actual maximum observed plasma concentration Model C max Calculated maximum plasma concentration Model T max Time of calculated maximum observed plasma concentration ORT Oral rehydration therapy SIG Strong ion gap T max Time of actual maximum observed plasma concentration