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Treatment of the Calf with Diarrhea
Abstract
from the colostrum as well as that actively produced by the calf itself; irregular feeding or overfeeding; the degree of confinement and crowding, which determines the pathogenic challenge to which the calf is exposed; and a multitude of stress factors such as inclement weather and difficult birth.
Calf scours may affect calves up to two months of age, but it is generally the greatest problem in calves less than two weeks of age, and frequently occurs in those less than one week old. In contrast, coccidiosis is more common in older calves and is generally hemorrhagic. Clostridial enterotoxemia causes sudden death more commonly than it causes diarrhea. Although large numbers of clostridia are present in the small intestine of some calves with diarrhea, they may not be the primary pathogen; therefore, their presence does not confirm clostridial enterotoxemia as the cause of the diarrhea. Salmonellosis occurs most often in calves two weeks to four months of age that are debilitated, stressed, and under close confinement. In some areas it may be endemic and therefore may be the most common cause of diarrhea in those calves. However, in most areas, calf scours is by far the most common cause of diarrhea in the calf. Frequently, the primary etiologic agent is not identified.
The two clinical forms of enteritis in the calf are septicemia endotoxemia and diarrheal dehydration. The septicemic-endotoxemic form is most common in calves that have been deprived of colostrum and occurs most commonly in the first few days oflife. This form of the disease has an acute, fatal course. Afflicted calves are often found dead without ever having been observed to be sick, and even before diarrhea has occurred. They account for less than 10 per cent of the cases reported, although in some herds, this form of the disease may be more prevalent.
The most common clinical manifestation of enteritis is diarrhea which results in extensive losses of fluids and electrolytes. These losses and their effects have been described in detail elsewhere 6 and are quite similar regardless of the causative agent. Therefore, the treatment of the calf with diarrhea is also quite uniform regardless of the etiology of the disease.
The most important aspect in the treatment of the diarrheic calfis the administration of fluids to replace the extensive losses of water and electrolytes that occur and which are responsible for the clinical signs and potential death of the calf. These fluids should also supply energy, particularly in patients requiring more than one or two days of treatment, since anorexia often accompanies the disease. Optimal administration of fluids requires familiarity with several general principles of fluid therapy. In addition, the selection of the route and rate of administration of fluids and the type of fluid used is based upon the acuteness of the illness and the degree of dehydration.
The degree of dehydration is best estimated from the clinical signs described in Table 1 . The amount of fluid needed as well as the condition of the animal can be determined from the degree of dehydration. For example, if a 30 kg calf is 10 per cent dehydrated, the amount of fluid needed to correct this dehydration is 30 kg times 10 per cent, or 3 liters.
Although the hematocrit and plasma protein concentrations increase linearly as diarrheal dehydration in the calf progresses,6 they are poor indicators of the degree of dehydration. Both parameters may vary widely in normal calves;6 therefore changes from an average value may be meaningless in any individual animal. However, changes in hematocrit and plasma protein concentration as well as in body weight are quite useful in determining whether fluid therapy is correcting the dehydration and compensating for the continuing loss of fluid. Weighing the patient periodically is one of the simplest and most reliable modes of assessment; it is also the most frequently overlooked method.
All fluids, regardless of the route of administration, should always be administered at body temperature. Warming cold blood to body temperature prior to massive blood transfusion decreased the incidence of cardiac arrest from 58 per cent to 7 per cent in one study in humans. 2 Ringer's lactate solution given intravenously at 5°C to five dogs in hemorrhagic shock resulted in three deaths. However, when five dogs with a similar blood loss were given the same amount of fluid warmed to body tempera- ture prior to administration, no deaths occurred. 2 Cold fluids given intravenously have a direct effect on the sino-atrial node, decreasing heart rate, cardiac output, blood pressure, and coronary artery flow, and causing death from arrhythmia and diminished contractility.2 Cold fluids given by nonintravenous routes are absorbed more slowly than are warm fluids.
Oral. Oral administration of fluids is always the route of choice in the treatment of the diarrheic calf, unless the condition is so acute that intestinal absorption is not rapid enough to keep up with losses of fluid or unless the animal is too severely dehydrated. If the animal is more than 6 per cent dehydrated or if the disease is fulminating, fluids must be given parenterally (Table 1 ). In these cases, however, giving fluids by both routes is beneficial and lessens the amount of fluids that must be given parenterally.
Oral fluid therapy has several advantages over the parenteral administration of fluids: the ability to give large volumes rapidly; a sustained input as fluids are absorbed; a lesser expense since the fluids need not be sterile and may be given by the owner; a less critical composition of the fluid compared with fluids given parenterally; and the relative safety of this route.
For best results, fluids administered orally should be formulated to afford the maximal rate of intestinal absorption. This is accomplished by using fluids which contain proteins or amino acids, glucose, sodium, and bicarbonate. These solutes have a synergistic effect on the rate of intestinal absorption of each other and, therefore, of water. 7 For example, the rate of intestinal absorption of sodium is greatly increased if glucose is present; conversely, the rate of intestinal absorption of glucose is more than doubled if sodi)1m is present. Of course, through salivary, pancreatic, and hepatic secretion, some sodium is always present in the intestine, but the quantity may not always be sufficient for maximal rates of absorption to occur. Absorption of water is passive; as solutes are absorbed, it is absorbed. Thus, to obtain the maximal rate of water absorption a fluid designed to attain the maximal rate of solute absorption is required. A number of fluids designed for this purpose are available commercially* or can be formulated as shown in Table 2 . Oral fluids constitute excellent media for microbial growth and are nonsterile; therefore, after use, the remainder should be refrigerated and, if not used within one to two days, it should be discarded.
The energy, amino acids, and proteins derived from oral fluids have a dual purpose. They not only enhance intestinal absorption but they also *Life Guard Oral-Norden Labs, Lincoln, Nebraska; Resorb-Beecham-Massengil, Bristol, Tennessee. assist in the nutritional maintenance of the animal. Although the energy and protein that most oral fluids provide are certainly of benefit, they are not sufficient to meet the animal's requirements. Therefore, additional energy must be provided if more than two days of therapy are required. Although the administration of oral fluids may increase the loss of fecal fluid, this does not negate their benefit. Their use will either reduce the net loss of water from the body or will result in a net gain of water. This is demonstrated in the example shown in Table 3 , in which, prior to receiving oral fluids, the calf had a net water loss and a decrease in body weight of I kg per day. When oral fluids were given, fecal losses doubled, but the calf then had a net water gain and an increase in body weight of I kg per day. Weighing the patient eight hours or so after administration of oral fluids will confirm whether or not the fluids given orally or by any other In preruminant calves and lambs, suckled fluids will bypass the rumen and reticulum and go directly into the omasum and abomasum. Nursed fluids, therefore, reach the intestine more rapidly than those given by stomach tube and are absorbed.more quickly. Thus, the calf should first be encouraged to nurse as much fluid as possible. The remainder of the fluids needed may be given by stomach tube. Most of the fluid administered by stomach tube is deposited in the rumen and takes longer to reach the intestine where absorption occurs. In some cases, this may be of benefit in providing a more prolonged therapeutic delivery.
The subcutaneous route of fluid therapy is quite useful in animals other than the horse and pig which lack sufficient subcutaneous space for the administration of significant volumes by this route. Fluids given subcutaneously are absorbed in four to six hours following administration. They provide a slow but sustained delivery of fluid during this period, which may be adequate iflosses of fluid from the body are not occurring faster than the rate of absorption. In more severe cases, the subcutaneous administration of fluids in conjunction with intravenous fluids may be quite beneficial and may lessen the amount of fluids that must be given intravenously. If the degree of dehydration is greater than 8 per cent, peripheral circulation is decreased to the extent that fluids given subcutaneously will not be absorbed or will be absorbed more slowly. After correcting dehydration, the continued absorption of additional fluids given subcutaneously can help in replacing continuing losses.
Fluids given subcutaneously should be sterile and warmed to body temperature. They should be from 1 to 1 Y2 times isosmotic. Electrolytes should be Y2 to 1 times isosmolality; they may contain from 0 to 2Y2 per cent glucose and generally contain at least 70 mEq per liter of sodium (Table 4 ). If their content varies from this formula, they will draw fluids or electrolytes out of the blood and may worsen the condition, at least initially. Addition of
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