by George Looby, DVM
Successfully treating diarrhea in the newborn of all species has long been a challenge to those charged with their care. Infants whose immune systems have yet to be developed rely on antibodies from their mother’s colostrum to provide the protection they need until their own systems can begin to provide some degree of protection. Despite the best efforts of their caregivers, very young farm animals are often exposed to a wide variety of organisms in their environment which can wreak havoc on them. Most often these invaders attack the gastro intestinal tract resulting in a loose, watery diarrhea which leads to dehydration and sometimes, if left untreated, death.
In the years before the advent of antibiotics the medications used to treat these animals were aimed at relieving the symptoms rather than addressing the cause but many did have a marginal degree of effectiveness when combined with good nursing care. With the advent of antibiotics, veterinarians and farmers had effective tools with which to work. For many decades this — combined with good husbandry practices — was the most effective method of dealing with this problem.
In recent years consumer groups and others have become increasingly concerned about the use of antibiotics in animals destined to enter the food chain with the possibility of various organisms developing a resistance to them. The debate regarding this practice goes on unresolved but there are researchers working at the cutting edge of immunology actively pursuing new methods of solving old problems. For several years dairy goats have been used where their milk is altered using genetic technology to provide components that could be used to treat conditions affecting humans. Goats were chosen as the ideal animal because of their size, disposition, relative low cost and world-wide distribution.
Over the past 30 years the application of transgenic technology in an ever-expanding number of areas has made previously difficult applications possible and increasingly affordable. Researchers are continually investigating and pursuing new pathways that will hopefully lead to the discovery of new uses for familiar materials. So it was with human lysozyme, an enzyme found in human milk that was known to have strong antimicrobial properties. For reasons still unknown, this characteristic is unique to the human species. The scientists involved in this area of study reasoned that if they could induce non-human females with higher levels of milk production to produce lysozyme, they might be on to something that would be of real benefit to infants of all species.
By using already-established technology, they took the DNA from a human and introduced it into the embryo of a goat which resulted in a doe with the capability of producing milk with lysozyme. This trait was passed on to her female offspring which eventually resulted in a herd of goats that were lysozyme producers. The ultimate aim of this trial was to determine if goat milk containing lysozyme might prove to be effective in treating newborns with induced diarrhea. Baby pigs were chosen as trial animals because their gastro intestinal tract most closely resembles that of the human and the ultimate reason for this entire experiment was to determine if goat’s milk would work. The litter of piglets was divided into two groups. One group was given goat milk containing lysozyme, the other was given goat’s milk with no enzyme. Both groups were given equal, carefully prepared extracts of a strain of E. coli known to cause diarrhea. That organism was chosen because it is everywhere in nature and is probably responsible for more neonatal dysentery world-wide than any other single organism. All environmental conditions were the same for both groups. Both groups began to show visable signs of infection within 30 hours of being given their coliform cocktail, but there was a significant difference in the severity of the disease between the two groups. Those in the lysosome group showed far less in the way of the obvious intestinal signs with which we are all familiar.
As is generally true in trials such as this, the piglets were sacrificed and the intestinal tracts examined both grossly and microscopically. Far less damage was observed in the tracts of those animals that had received the milk containing lysozyme.
It is estimated that world-wide over one million infants die each year as the result of diarrhea, the majority of these in third world, and this loss could be dramatically reduced if a safe, economical, readily available treatment could be made available. The domestic animal most common in these countries is the goat and if a percentage of these in any given area could provide a life-saving component a major break- through would occur.
Diarrhea is especially dangerous in newborns who have no innate resistance, especially those who received an inadequate quantity or poor quality colostrum. The bacteria that causes the condition releases toxins which causes the body to set up an inflammatory response which brings in immune cells to fight the bacteria. The resulting damage to the cells lining the intestinal tract allows water to enter the gut which in turn results in diarrhea. The loss of water from the body, the quantity of which is small in the newborn, leads to dehydration, the loss of vital nutrients, electrolytes and malnutrition.
While this one trial is encouraging it cannot be taken as the definitive answer to this age old condition. Other work is sure to follow that will further substantiate the findings. This work was conducted and reported by Caitlin A. Cooper, Lydia C. Garas Klobas, Elizabeth A. Maga and James D. Murray in the journal Plos One.