M. G. FINCHER.
CALF SCOURS is perhaps the most important of the diseases of calves. It is known also as diarrhea in calves, calf septicemia, and 3-day calf disease.
It takes many different forms and therefore is hard to define. Here, though, I describe the types that are seen a few hours after birth and those that appear later.
The most fatal form of calf scours appears at birth or within 6 to 72 hours after birth. The calf is found soon after birth in a cold, weak, and dying condition.
Sometimes there is little or no evidence of actual passage of watery feces, and several calves on a farm may be "found dead" unless they are closely watched following birth. In other herds a few calves may scour mildly or severely during the first 10 to 30 days of life and recover with little assistance. Oftener, however, calves with severe diarrhea become unthrifty and potbellied, show poor growth, and get pneumonia.
The middle ear, joints, and umbilicus in rare instances become seats of localized infection in beef or dairy calves when they are a few days to several weeks old.
WE DO NOT KNOW all the factors that favor development of the various forms of diarrhea in calves. Many causes are known, but others undoubtedly have escaped detection.
Various infections may be to blame. Usually a calf reared from an isolated family cow on a small farm remains free of scours and grows better than do calves in larger herds in expensive but crowded calf barns. Presumably, therefore, infectious agents may be regularly present in most large herds.
The organisms capable of causing scours include the coliform group. The salmonella group is involved infrequently in California and other parts of the world. Possibly viral agents are the cause. The salmonella or paratyphoid organisms seldom have been recognized in calves in the eastern part of the United States.
Calf pens, parturition stalls, barnyards, trucks, and railroad cars may be contaminated by these infectious agents and may be a source of infections that cause mild to fatal scours.
Adult or younger cattle very likely carry the agents on their feet and skins. It is believed that the uterus and digestive tract of adult cattle do not generally harbor the infectious organisms.
AN UNUSUALLY SEVERE type of acute calf septicemia or calf scours, with death of some calves, will occur quite regularly when a large group of very young calves is assembled from different farms, because the virulence and the variety of the causative agents associated with calf diseases are thereby increased.
The removal of pregnant cows from an area where fatal scours is rampant and allowing them to calve in isolated stables or grass paddocks or on pasture often stops an outbreak immediately.
Calves born in a particular set, of buildings, stalls, or outside yards may die of severe septicemia with or without scours over a period of a few weeks or several months. If the pregnant cows are moved to one or preferably to several new, clean stables or yards, the losses may suddenly stop. This strongly suggests that some type of infection (virus, bacteria, or both) occurs promptly after the calf is dropped in an infected place on the farm or ranch. Leaving this infected area and moving the remaining pregnant females to one or several uninfected areas avoids the chance for exposure to infection of calves born after the move.
The cow's diet during the several weeks before she drops her calf influences the calf's resistance to scours. The dam's lack of vitamin A (and perhaps other vitamins) may weaken the calf even though she herself is not emaciated.
A low amount of vitamin A in the calf's liver and in the dam's colostrum may result from poor pasturage and too little roughage and concentrates during the last months of pregnancy. When cows have been on poor winter rations or on extremely dry pasture, one can expect severe outbreaks of scours and other diseases of calves.
Colostrum from the dam of the calf or from some other cow, fresh within 12 to 24 hours, contains gamma globulins rich in antibodies. If the calf gets no colostrum in the first several hours of life, scours are likely to ensue. Yet this colostral milk has a high content of fat (and perhaps other products), which produces scours if the calf gets too much. Calves of high-butterfat breeds especially may become extremely sick from too much colostrum even if infection is absent.
CALF DISEASES, including scours, seem to be more severe and widespread in some years than in others. We do not know why. It may be due to lack of agents that produce immunity antibodies in the cows and in their colostrum and, therefore, high susceptibility to viruses or other agents in the newborn calves. Then, as the diseases became widespread, the calves might have acquired some immunity, perhaps from their dams, and the incidence would be lower for several years.
A virus has been isolated from calves and cows near Ithaca, N. Y., and other parts of the United States. It can cause virus diarrhea. It has not been classed as a true cause of white scours or scours in calves under 3 weeks old, but it deserves attention as a threatening or possible cause. Most 3-month-old calves in the Ithaca section are resistant to artificial inoculation with the virus. Therefore the virus may have entered the young calves and built up resistance in them. It is debatable whether it has caused clinical symptoms, except a mild fever and resistance to that particular virus.
SOME RESEARCH MEN have suggested that some cases of scours are due to the same cause that is connected with diarrhea in human infants. It is called metabolic acidosis and is accompanied by low blood sugar and a low potassium level in the blood. Great variation in the blood chemistry has been found, however. The presence of a severe to moderate acidosis and the variations in the sodium and calcium levels in the blood of affected calves deserves more study before they can be positively evaluated. No doubt metabolic acidosis is a cause or a result of scours.
Some calves, as the late D. H. Udall pointed out years ago, develop depraved appetites and eat contaminated bedding. Their true stomachs (abomasum) at a week of age may contain shavings, coarse straw or hay, and hair, mixed in an indigestible mass. They remain unthrifty and develop so-called dietetic scours.
Furthermore, many calves are deprived of cows' milk when they are 3 to 15 days old. Veterinarians generally believe that calves should get milk longer than that. Various milk substitutes are widely used. Most of them contain dried skim milk, antibiotics, chemicals, carbohydrate filler, and vitamins. We have seen many calves that died of dietetic or nutritional scours or did not thrive because they got no fresh whole milk. And we have seen calves that were fed such artificial diets and seemed highly susceptible to ordinary infections even though they grew well.
In sum, then, scours seems to be due largely to an overcrowded condition, poor hygiene, poor diet for the calves or for their dams, and to a variety of infectious agents, which may enter by ingestion, inhalation, or through the umbilical stump.
ACUTE CALF SEPTICEMIA is a striking and costly form of the syndrome a complex set of symptoms called calf scours.
Usually the calves with this condition die suddenly. A few calves have a fetid, white, watery diarrhea soon after birth. A series of losses may occur despite drastic steps to cure or prevent the diarrhea. Then for several years the disease may not appear in such a virulent form on the same premises. Or it may recur a few weeks each year on larger farms. Or, again, calves may have a fetid, watery diarrhea, may be clammy and cold, and may have sunken eyes when they are 6 to 24 hours old a syndrome that is a continuous experience each year throughout the long calving season, especially in winter and spring in the Northeast. Severe outbreaks may occur in hot weather, too.
Calves that survive may respond well to good husbandry and become useful adults. A few will remain unthrifty and stunted, with conformation much poorer than their inherited potential, and develop considerable pneumonia. Chronic solidified areas will be found in their lungs at autopsy.
The absence of a temperature in many of the so-called "3-day scours" or very acute cases often is confusing and surprising. It probably means that the loss of fluids through the bowels has been so rapid that the patient is approaching shock and more complete dehydration and death. Owners may not have noticed that the calves were sick and the veterinarian may have found nothing at autopsy. There is a total absence of gross changes in the tissues. If the examination is performed immediately after death, hemorrhages may be found on the sclera of the eye or in the stomach, kidneys, or intestines, and the contents of the stomach and intestines have a fetid smell. Feces on the buttocks and tail have an extremely offensive odor.
Calves in most herds may die before the onset of the acute type of the disease. They start showing white or greenish-gray, fetid feces at 24 hours (or as late as 10 days) after birth. Usually these calves are not especially depressed and cold and will get up to nurse or suck a nipple pail despite severe diarrhea. Like the more severe form, this common "white scours" may lead to an unthrifty calf. Fetid, purulent discharges may come from the ears or umbilicus. Joint changes and lameness (arthritis or tendovaginitis) may set in. Eventually pneumonia, repeated attacks of constipation, or scours and unthriftiness may occur.
Older calves that have escaped the baby-calf type of septicemia and scours occasionally may develop troublesome and apparently contagious diarrhea. This form of diarrhea affects one or several calves Ito 6 months old in a herd. The liquid feces often are nearly black. That is due perhaps to a medicine that did not stop the diarrhea but changed the character and color of the feces, or it may be due to blood in the feces. That blood would have come from the true stomach or small intestines; any fresh blood might come from the large bowel or rectum.
These late cases of scours in older calves may be a symptom of an unrecognized chronic pneumonia or be part of other localized infections following sickness in early calfhood. Such chronic scours often represents evidence of a poor diet and poor housing or general environment. Standing or lying in the mud or water-soaked bedding seems to favor the development of this and other forms of scours.