Abomasal ulceration and tympany of calves.

This article reviews the current knowledge on the pathophysiology of abomasal ulcer formation and abomasal tympany in calves. The development of ulcers and bloat has been attributed to many factors, including coarse feed, environmental stress, vitamin and mineral deficiencies, and bacterial infections. This article discusses various factors thought to play a role in the development of these abomasal conditions in calves.

Effect of suckling an isotonic solution of sodium acetate, sodium bicarbonate, or sodium chloride on abomasal emptying rate and luminal pH in calves.

OBJECTIVES: To compare abomasal emptying rates in calves after suckling milk replacer or 3 common orally administered electrolyte solution components. ANIMALS: 5 male calves < 35 days of age. PROCEDURES: Calves with a cannula fitted in the abomasal body were fed 2 L of milk replacer with or without parenteral administration of atropine (0.01 mg/kg, i.v., then 0.02 mg/ kg, s.c., q 30 min) or isotonic (150 mM) solutions of sodium acetate, NaHCO(3), or NaCl in a randomized crossover design. Abomasal emptying rates were determined via scintigraphy, acetaminophen absorption, ultrasonography, and change in abomasal luminal pH. RESULTS: Scintigraphic half-emptying time, time of maximal plasma acetaminophen concentration, ultrasonographic half-emptying time, and pH return time indicated similar abomasal emptying rates following suckling of isotonic sodium acetate, NaHCO(3), and NaCl solutions, whereas the emptying rate of milk replacer was significantly slower. Mean maximal abomasal luminal pH was highest following suckling of NaHCO(3) (pH(max)=7.85) and lowest following suckling of NaCl (pH(max)=4.52); sodium acetate (pH(max)=6.59) and milk replacer (pH(max)=5.84) yielded intermediate pH values. CONCLUSIONS AND CLINICAL RELEVANCE: Isotonic solutions of sodium acetate, NaHCO(3), and NaCl were rapidly emptied from the abomasum but varied markedly in their ability to alkalinize the abomasum. Sodium bicarbonate-containing orally administered electrolyte solution might increase the frequency of infection or severity of clinical disease in diarrheic calves treated for dehydration by causing prolonged abomasal alkalinization.

Effect of suckling isotonic or hypertonic solutions of sodium bicarbonate or glucose on abomasal emptying rate in calves.

OBJECTIVE: To determine and compare the abomasal emptying rates in calves suckling milk replacer or an isotonic or hypertonic solution of NaHCO(3) or glucose. ANIMALS: 5 male Holstein-Friesian calves that were < 30 days of age. PROCEDURES: Calves were fed 2 L of milk replacer or isotonic (300 mOsm/L) or hypertonic (600 mOsm/L) solutions of NaHCO(3) or glucose containing acetaminophen (50 mg/kg). Venous blood samples and transabdominal ultrasonographic abomasal dimensions were obtained periodically after feeding, and abomasal luminal pH was continuously monitored by placement of a luminal pH electrode through an abomasal cannula. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration, ultrasonographic determination of the half-time of abomasal emptying, and the time for luminal pH to return to within 1 pH unit of the preprandial value. RESULTS: Hypertonic NaHCO(3) solution was emptied slower than an isotonic NaHCO(3) solution, isotonic glucose solution was emptied slower than an isotonic NaHCO(3) solution, and hypertonic glucose solution emptied slower than an isotonic glucose solution. CONCLUSIONS AND CLINICAL RELEVANCE: An electrolyte solution for oral administration with a high osmolarity and glucose concentration may lead to a slower resuscitation of dehydrated diarrheic calves because such solutions decrease the abomasal emptying rate and therefore the rate of solution delivery to the small intestine. Whether slowing of the abomasal emptying rate in dehydrated diarrheic calves suckling an oral electrolyte solution is clinically important remains to be determined.

Determination of abomasal emptying rate in suckling calves by use of nuclear scintigraphy and acetaminophen absorption.

OBJECTIVE: To develop nuclear scintigraphic and acetaminophen absorption methods for measuring abomasal emptying rate in suckling calves. ANIMALS: 9 male Holstein-Friesian calves < 30 days old. PROCEDURE: Calves were fed 2 L of milk replacer, fresh cow's milk, or an isoosmotic (150mM) solution of NaCl, NaHCO3, or sodium acetate containing technetium TC 99m-diethylenetriamine-pentaacetic acid (370 MBq) and acetaminophen (50 mg/kg). Right lateral scintigraphic images and venous blood samples were obtained periodically after feeding. Two power exponential equations were fitted to the scintigraphic data, and 3 pharmacokinetic models were fitted to the acetaminophen concentration-time data. RESULTS: Data from 32 feedings were analyzed, with half emptying time for scintigraphic evaluation ranging from 29 to 202 minutes. Siegel's modified power exponential equation provided a better description of the scintigraphic data than did Elashoff's power exponential equation. The first derivative of Siegel's modified power exponential formula provided the best pharmacokinetic model for the acetaminophen absorption data. Time to maximal acetaminophen concentration (Tmax) provided the most accurate index of abomasal emptying rate from the acetaminophen concentration-time data. CONCLUSIONS AND CLINICAL RELEVANCE: Abomasal emptying rate is best determined in healthy suckling calves by use of Siegel's modified power exponential equation to model the scintigraphic data. Pharmacokinetic calculation of Tmax from the acetaminophen absorption curve provides an alternative method for determining abomasal emptying rate in healthy suckling calves that is accurate, inexpensive, practical, and safe. However, it is unclear whether diarrhea would alter the acetaminophen absorption curve in calves.

Ultrasonographic measurement of abomasal volume, location, and emptying rate in calves.

OBJECTIVE: To develop and validate an ultrasonographic method for measuring abomasal volume, location, and emptying rate in suckling calves. ANIMALS: 9 male Holstein calves < 40 days of age. PROCEDURE: Before and after calves were fed different volumes of milk replacer or 2 L of oral electrolyte solutions, ultrasonographic measurements of abomasal dimensions (width, length, and height) were obtained by applying a 3.5-MHz sector probe to the ventral aspect of the abdomen in the transverse and sagittal planes. Abomasal volume was calculated from the ultrasonographic measurements by modeling the abomasum as an ellipsoid and by use of a power exponential equation to calculate the half-time of abomasal emptying (t1/2). RESULTS: Preprandial abomasal volume was 20 to 137 mL. All 3 abomasal dimensions increased during feeding and after suckling, and the abomasum was symmetrically located about the midline of the ventral aspect of the abdomen. Strong linear relationships were identified between ultrasonographic and suckled volumes, between ultrasonographic and scintigraphic heights, and between ultrasonographic and scintigraphic lengths. Ultrasonographic t1/2 was linearly related to scintigraphic t1/2; the latter is regarded as the gold standard measure of gastric emptying rate. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonographic evaluation of the abomasum appears to provide a practical, rapid, noninvasive, and accurate method for determination of abomasal volume, location, and emptying rate in suckling calves.