| Popis: |
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 that is reliable, practical, and economical. After instrumentation and recording baseline data, diarrhea and dehydration were induced by administering milk replacer [16.5 mL/kg of body weight (BW), PO], sucrose (2 g/kg in a 20% aqueous solution, p.o.), spironolactone and hydrochlorothiazide (1 mg/kg, PO) every 8 h, and furosemide (2 mg/kg, i.m., q6h). Calves were administered sucrose and diuretic agents for 48 h to induce diarrhea and severe dehydration. Clinical changes after 48 h were severe watery diarrhea, severe depression, and marked dehydration (mean, 14% BW loss). Cardiac output, stroke volume, mean central venous pressure, plasma volume, thiocyanate space, blood pH and bicarbonate concentration, base excess, serum chloride concentration, and fetlock temperature were decreased. Plasma lactate concentration, hematocrit, and serum potassium, creatinine, phosphorus, total protein and albumin concentrations were increased. This non-infectious calf diarrhea protocol has a 100% response rate, while providing a consistent and predictable hypovolemic state with diarrhea that reflects most of the clinicopathologic changes observed in osmotic/maldigestive diarrhea caused by infection with rotavirus, coronavirus or cryptosporidia. Limitations of the protocol, when compared to infectious diarrhea models, include failure to induce a severe metabolic acidosis, absence of hyponatremia, renal instead of enteric loss of chloride, renal as well as enteric loss of free water, absence of profound clinical depression and suspected differences in the morphologic and functional effect on intestinal epithelium. Despite these differences, the sucrose/diuretic protocol should be useful in the initial screening of new treatment modalities for calf diarrhea. To confirm their efficacy, the most effective treatment methods should then be examined in calves with naturally-acquired diarrhea. |
