A RELIABLE, PRACTICAL, AND ECONOMICAL PROTOCOL FOR INDUCING DIARRHEA AND SEVERE DEHYDRATION IN THE NEONATAL CALF

Fifteen healthy, colostrum-fed, male dairy calves, aged 2 to 7 d were used in a study to develop a diarrhea protocol for neonatal calves tha t is reliable, practical, and economical. After instrumentation and re cording baseline data, diarrhea and dehydration mere induced by admini stering milk replacer [16.5 mL/kg of body weight (BW), PO], sucrose (2 g/kg in a 20% aqueous solution, PO), spironolactone and hydrochloroth iazide (1 mg/kg, PO) every 8 h, and furosemide (2 mg/kg, IM, q6h). Cal ves were administered sucrose and diuretic agents for 48 h to induce d iarrhea and severe dehydration. Clinical changes after 48 h were sever e watery diarrhea, ser ere depression, and marked dehydration (mean, 1 4% BW loss). Cardiac output, stroke volume, mean central venous pressu re, plasma volume, thiocyanate space, blood pH and bicarbonate concent ration, base excess, serum chloride concentration, and fetlock tempera ture were decreased. Plasma lactate concentration, hematocrit, and ser um potassium, creatinine, phosphorus, total protein and albumin concen trations were increased. This noninfectious calf diarrhea protocol has a 100% response rate, while providing a consistent and predictable hy povolemic state with diarrhea that reflects most of the clinicopatholo gic changes observed in osmotic/maldigestive diarrhea caused by infect ion with rotavirus, coronavirus or cryptosporidia. Limitations of the protocol, when compared to infectious diarrhea models, include failure to induce a severe metabolic acidosis, absence hyponatremia, renal in stead of enteric loss of chloride, renal as well as enteric loss of fr ee water, absence of profound clinical depression and suspected differ ences in the morphologic and functional effect on intestinal epitheliu m. Despite these differences, the sucrose/diuretic protocol should be useful in the initial screening of new treatment modalities for calf d iarrhea. To confirm their efficacy, the most effective treatment metho ds should then be examined in calves with naturally-acquired diarrhea.