Bacterial Infections of the Intestines

Considering the movement and trade in pigeons over the world, fanciers should not be surprised when a variety of diseases occur in our pigeons over a period of time. In most cases, there is a triad of circumstances consisting of: 1) the resistance (or lack of) of the pigeon, 2) the presence of the bacterium, virus or parasite, plus 3) the environmental or stressful conditions that permit the particular disease to occur. It is the interaction of these three factors in any bird or amimal that determines whether disease will occur.
Note that infection itself by a given disease-causing agent does not necessarily mean the existence of overt disease. For example, the presence of a few coccidia in the intestines of resistant pigeons tends to maintain a very high level of immunity to that type of coccidia. This situation is most certainly infection of tissues of the intestines. However, coccidiosis, the disease, is not present. In this case, there is a good balance between the presence of a few coccidia and the immune system of the bird which is able to control the numbers of coccidia quite well.
However, frank disease may occur if circumstances tip the balance in favor of the coccidia. For example, persistently wet floors during a rainy period, or overflowing waterers that keep the floor constantly wet, can change the balance. In this situation of cool, damp conditions that are ideal for coccidia and other parasites, those coccidia shed in droppings are now able to develop further to a stage that makes them infective and therefore, potentially dangerous.
Very quickly, under these wet conditions, many thousands of infective forms of the coccidia can develop on the floor. Birds picking around the floor can swallow many of these infective stages, and as a result, there may be an overwhelming challenge to the immune system as numerous coccidia invade cells of the inner surface of the intestines, and the birds develop signs of the disease coccidiosis. Youngsters represent an age class that is particularly vulnerable because these birds have not yet had an opportunity to develop good immunity through exposure to low numbers of coccidia in the environment. Instead, they are now faced with a massive, overwhelming challenge, and the result can be a severe outbreak of coccidiosis.
Other organisms, notably the bacteria, but also the viruses, chlamydia, etc., often operate in the same way, taking a biological advantage when environmental circumstances are favorable and there is a concurrent relaxing or failure of defence mechanisms in the birds. Salmonella spp. (also called paratyphoid organisms), and also E. coli, are bacteria that represent other examples of the same situation.
In pigeons, the most common Salmonella sp. is Salmonella typhimurium variety copenhagen, although several other strains of salmonella organisms can certainly be involved in producing disease in pigeons. Variety copenhagen seems to have a close and even specific relationship with pigeons. If there is any good news (or maybe more correctly, less bad news!) about salmonella infections, some of it is associated with variety copenhagen . Firstly, this strain is often highly sensitive to a very wide range of antibiotics and other anti-bacterial drugs. Secondly, this strain seldom ever causes infection in humans. This is a significant point because the major importance of most strains of Salmonella sp. is their known capacity to leap species barriers and infect quite a number of classes of birds and animals, including humans. In general, Salmonella typhimurium variety copenhagen seems to be most associated with pigeons, even though at times, it is able to infect other species such as chickens.
Problems with Salmonella sp. and E. coli infections in pigeons are most common in younger birds. Adult birds often don't have signs of infection, but in some instances, they too can become infected and develop overt signs of disease. Youngsters with salmonellosis develop diarrhea that is often green. This occurs because the intestines are empty of food, and only bile-stained fluids pass through as droppings. Later, in a more chronic stage that occurs after these bacteria invade the bloodstream, they can then move into and infect joints which become inflamed, swell and result in nodular lumps on wing or leg joints.
A number of antibiotics and other anti-bacterial products can be used in treatment, with varying degrees of success. Part of the reason for this fact is that, although most infected birds (or any animal, bird or human) infected with a Salmonella sp., completely eliminate the infection, the occasional bird or animal will remain a permanent carrier of the organism -- and this is the catch. Such carriers are generally very healthy, with no visible indication that they harbor the organism, but they continue to be a ready source of Salmonella sp. organisms for other birds in the loft. In many species, these bacteria likely hide in the gall bladder, but as pigeons don't have a gall bladder, the organisms likely live in the bile ducts of the liver.
If conditions are ripe, and carrier birds become stressed from feeding, weaning, racing, etc., such birds can begin to shed greater numbers of these bacteria from the bile ducts into the intestines, and from there they are passed in droppings into the environment. If susceptible birds, including youngsters in particular become exposed, they can develop serious disease after swallowing numbers of these bacteria.
Stress produces chemical and cellular changes that decrease the ability of the body to defend itself against infection. Opportunistic organisms such as Salmonella sp., among others, take advantage of the situation and begin to multiply and produce thousands, and likely millions more organisms that are shed in droppings to contaminate the local environment from which they are picked up and swallowed.
As mentioned earlier, antibiotic treatment can be highly successful in many birds, but the very real possibility that a carrier bird may exist in the loft after the infection has gone through many or all birds, poses a continuing threat to the health of the entire loft. The use of sodium acid sulfate as a loft dressing on floors, perches and nestboxes is a chemical approach that has merit because it creates an acidic environment that a number of disease-producing organisms, especially intestinal bacteria, find too hostile for survival.
As fanciers, we can use this information to our own advantage. E. coli and Salmonella sp. bacteria much prefer to live in an alkaline environment, so it is obvious that the use of lime as floor, perch and nestbox dressings should be avoided when infections caused by Salmonella sp. and E. coli occur.
As well as the use of antibiotics, there are other management approaches to prevention and treatment as well. In 1973, a man named Esko Nurmi in Finland developed a procedure in which he fed to normal, day-old chicks, litter and droppings from salmonella-free, clean, healthy flocks of chickens. Afterward, he found that these chicks were resistant to a challenge dose of salmonella organisms given to them by mouth.
The principle behind this process is that "good" bacteria in the droppings of clean flocks of birds colonized the intestines of these chicks and simply overwhelmed sites of invasion by salmonella organisms. The same principle applies when a broody chicken scratches in the soil and calls her chicks to pick in that area. The intestines of these chicks are colonized very quickly with masses of "good" bacteria picked up in the soil at this time. In other words, this defence network competes with and excludes disease-producing bacteria -- hence the expression competitive exclusion.
The means by which this protection against salmonella and other disease-producing bacterial organisms is accomplished are not completely understood. However, there are two known mechanisms that operate to protect birds against disease when the principle of competitive exclusion is applied. Firstly, the "good" bacteria in the normal droppings seem to form within the intestine, a physical barrier that may be 10-12 bacteria deep. These protective bacteria actually bind to specific sites on the inner surface of the intestine, and by this means, prevent the attachment of Salmonella sp. on the inner surface of the intestine, and so, prevent these disease-producers from breaching the wall of the intestine and entering the bloodstream.
The second process that occurs is an actual chemical alteration in the intestine. The "good" bacteria in clean droppings are anaerobic species (an = without; aerobic = oxygen, that is, without oxygen), ie, they are able to live and reproduce in an environment in which levels of oxygen are very low. In such a situation, the life processes of these bacteria are completed in an anaerobic state. In such an anaerobic environment, these organisms produce and excrete lactic acid as one of the by-products of their life processes. In turn, the lactic acid that is excreted by the bacteria into the surrounding environment of the intestine, creates a shift from a normally alkaline state to a more acidic condition in the intestine.

The importance of this fact is that, as mentioned previously, many disease-producing bacteria like Salmonella sp. and E. coli, for example, like to live in a slightly alkaline environment where they can reproduce well. In an acidic environment, they are prevented from reproducing, and their numbers drop dramatically, in some cases by 97% or more. One of the many "good" bacteria present is the Lactobacillus sp. that we also find in yogurt and similar products used for human food. Other "good" bacteria that are also present in yogurt include two species of Streptococcus, among others. Dr Kevin Zollars has mentioned this point more than once in his informative articles in the Digest.
The Lactobacillus sp. bacteria not only multiply and colonize the intestines, but they also attach to the wall of the crop, and are mixed with food that has just been eaten. As the food moves into the proventriculus and gizzard, and then into the intestine, the "good" Lactobacillus sp. bacteria move mechanically with it and multiply in the intestine. However, scientific information obtained from trials using several pure cultures of Lactobacillus sp. in chickens showed that this organism alone was not capable of conferring on chickens, the desired resistance to Salmonella spp.. Additional methods had to be incorporated with the use of Lactobacillus sp..
A few basic products incorporating these ideas of using "good" bacteria to combat Salmonella sp. infections are being examined in the poultry industry. One of these products is called "an unidentified culture". In this situation, intestinal contents from chickens known to be salmonella-free are incubated in a warm, anaerobic environment. The bacteria that are grown in this way are not specifically identified, but this culture is then fed to the birds.
The second of these products is called "a defined culture", meaning that specifically identified bacteria from a culture of intestinal contents of normal chickens are included in a mix of bacteria that may contain up to 50 different species of bacteria. Thirdly, there are products called "probiotics" which are cultures of only a very few kinds of bacteria, ie, for example, the kinds that are found in yogurt. One such starter product for preparing yogurt at home contains a Lactobacillus sp., as well as two identified species of Streptococcus. All of these products are given to birds by mouth, often through feed or drinking water. (The advertising columns of racing pigeon magazines offer similar products for use in drinking water. No doubt, many are good products, but in the past, I have cultured at least one widely touted, advertised product and found very few bacteria present.)
In the poultry industry, these bacterial products are being used in at least three situations:
1. They are given to day-old chicks to allow the rapid colonization of the intestine with "good" bacteria.
2. In mature breeder chickens, these products are used if there has been an outbreak of salmonella infection. Birds are first treated with an appropriate antibiotic, after which they are given the "unidentified culture" to prevent re-infection.
3. At times of stress, these products are given to increase the numbers of "good" bacteria that, in turn, will increase the acidity of the intestines, and thereby decrease the risk of an outbreak of intestinal disease.
These products are alive, ie, they contain live bacteria, and in order to be useful, the bacteria have to remain alive. So, exposure to sunlight or heat during periods of storage will adversely affect these cultures. They must not be mixed in water that contains chlorine, iodine or other disinfectants, simply because these chemicals will kill the desirable bacteria in the culture. Similarly, they can't be used when there are antibiotics in the water, for the same reason. In poultry, only the "unidentified culture" appears to be effective against salmonella organisms. "Defined cultures" and "probiotics" are more effective against disease-producing strains of E. coli, than they are against Salmonella spp., for example.
Yet another class of probiotics are the organic acids, that include lactic, formic, and propionic acids, that are being added to feed and water for poultry, to produce the same effect, ie, acidification of intestinal contents to increase resistance to disease-producing bacteria in the intestine.
Even given some of the limitations of these different products, it is known that methods that will 1) effectively "block out" disease-causing bacteria, and 2) create an acidic condition in the intestines of birds will help to eliminate or markedly reduce the numbers of a variety of disease-producing bacteria. (Unfortunately, they don't have any effect on coccidia or worms.) Two small examples from my own limited experience:
A pigeon fancier who had a number of undetermined losses associated with diarrhea in nestlings, decided to try this non-antibiotic approach. He obtained a package of yogurt starter, mixed it with warm milk, incubated it in a warm place to allow the bacteria in the starter to multiply, and added it to a mixture of small grains and rolled oats, to produce a somewhat crumbly, semi-dry mash that he placed in a feeder on the floor. His old birds took to this mixture avidly while they were feeding youngsters. The result was that no more youngsters were lost, and the health of remaining birds improved markedly.
In another example, a fancier was having problems with the intestinal infection called ulcerative enteritis (caused by the bacterial organism called Clostridium colinum) in youngsters aged 12-20 days, the age that seems to be most critical for the occurrence of this bacteria-caused disease. Some youngsters in the first round had been affected and he decided to try to prevent it in the second round. He mixed plain yogurt with enough warm water to make a thin milkshake-like solution, stirred it to remove any lumps, and gave it by feeding tube to 10-11 day-old youngsters in the nest, before there was any sign of disease. This was done twice and sometimes three times a day for 4-5 days. Result: no evidence of ulcerative enteritis in any of these youngsters.
Both of these cases definitely don't represent solid scientific proof of the effectiveness of this type of product because no group of youngsters was left untreated for comparison. However, there were very strong indications from these limited trials that there may be a great deal of merit in this approach to prevent some bacteria-caused infections of the intestines -- in spite of studies that showed very little positive effect in eliminating or reducing the numbers of Salmonella sp. by the use of cultures of Lactobacillus sp. alone.
What are some other stressful situations that could lend themselves to this application? One of the most obvious times occurs when youngsters are weaned, when stresses are very high: they have been separated from their nestbox and close parental care, they are now in strange, unfamiliar surroundings, and they may be frightened, tired, hungry and thirsty. If the weather is also bad, add another stress to the list. Possibly just before weaning and through the first 2-3 days after weaning, the addition of yogurt or yogurt starter slurry in a mash feed or in drinking water might be enough to load the crop and intestines of these youngsters with a formidable barrier of protective lactobacilli and streptococci.
Practically speaking, it would seem best to try mass treatment of the entire flock, and to use most of these procedures at regular feeding times, so that parents will eat fresh crumbly mash or drink fresh water containing these "good" bacteria, which are then fed immediately to youngsters in the nest. Weaning youngsters onto such a mash, or providing water containing these bacteria after weaning would also be practical. I have found that a tablespoonful of plain yogurt added to a gallon of drinking water seems to be very helpful. When first used, large amounts of yogurt may cause birds to back away from the drinker, but if smaller amounts, say a quarter to half teaspoonful, are used for a few days, birds become used to the taste.
Two other critical times during which these preparations could be useful are just before shipping birds -- old or young -- to a race, and/or just after the birds return from a race. If birds are sent racing with a protective wall of "good" bacteria lining the crop and intestines, this procedure could this be effective in preventing establishment of colonies of disease-producing strains of Salmonella sp. and E. coli picked up in shipping baskets.

Work with poultry has demonstrated a definite decrease in numbers of Salmonella sp. in these birds if "good" bacteria are allowed to become established in the intestines before there is any exposure to salmonella organisms. Logically then, the most opportune time to use these methods is a day or two before birds enter the shipping baskets to be certain that the intestines are well colonized by "good" bacteria beforehand. A similar process used right after birds return from a race also might help to prevent infection at this stressful time. Another point is that if returning racers bring with them Salmonella sp. or disease-causing strains of E. coli, the use of these products both before and after the race might also protect stock birds, racers and youngsters that remained at home. Exhausted, flown-down birds that return days or weeks late, possibly injured, from tosses or races, would seem to be ideal candidates for this type of therapy, given the high level of stress they have been and are under. These methods would be equally useful in all new birds acquired locally or from Europe, etc..
Birds, especially youngsters, that are ill from other infections such as circovirus infections, canker or coccidiosis, could be highly susceptible to intestinal infections, and might benefit considerably from a treatment of "good" bacteria at this time. Note again: It is highly important that you don't mix antibiotics in the water if you also plan to add "good" bacteria. The antibiotics will kill these bacteria in the same way that they kill disease-causing bacteria. If antibiotics are judged to be necessary, use them first for the required number of days, and then add "good" bacteria to fresh water after the antibiotic treatment has been completed.
Two additional approaches with a similar objective are used today in the poultry industry, with special emphasis on eliminating Salmonella sp. from breeder flocks, and even broiler flocks. One of these procedures is to add the sugar lactose to pelleted rations or to drinking water at the level of about 5%. A good practical source of lactose is whey powder (it is about 70% lactose), available at feed companies, milk and cheese factories, and food stores, and can be added to drinking water. The principle is this. When whey is swallowed, the lactose present is converted by "good" bacteria in the crop and intestines into lactic acid, which, in turn, shifts conditions to the acid side of neutral, and provides the same kind of control over disease-causing bacteria in the intestines.
The other modern approach uses combinations of the organic acids, lactic, formic and propionic -- mentioned earlier in this article -- which do the same thing, ie, acidify intestinal contents to create a hostile environment for disease-causing bacteria. These products are available for use in pelleted feeds, as well as for drinking water for poultry, and could easily be adapted for use in pigeons, especially the water formulation. Check with your local co-op or feed company for these products, often called "acid packs". Directions for use are given on the container or package.
Pigeons are not poultry, so why use methods developed for the poultry industry? Well, as I see it, there is just no point in letting good scientific information from one species go to waste, when there could be direct application of the same principles in another species -- in this case, racing pigeons. Sometimes it seems that there is a real scarcity of good scientific information on racing pigeons, particularly because of the great secrecy that abounds in the sport, and until we become more open as racing pigeon sportsmen and women, we have to be able to borrow useful information and ideas from other domestic species, and adapt them for use in pigeon racing.
From the foregoing information, it is obvious that, not only is one of these procedures valuable and practical, but also, combinations of these approaches just add more arrows to your bow, so to speak. So, the addition of Lactobacillus and Streptococcus spp. cultures from yogurt or similar products (friendly bacteri) to feed or water can easily be combined with the addition of organic acids and/or lactose, to insure that intestinal contents become acidic, and therefore, protective against serious disease-causing bacteria such as Salmonella, E. coli, and Clostridium spp. of bacteria, among others.
A major point about the use of "good" bacteria, lactose, and organic acids, singly or in combination, is that by these means, we should be able to begin the process of halting the uncontrolled, cavalier use of cocktails of antibiotics and other anti-bacterial drugs so much in use --and abuse-- not only by fanciers, but also by many segments of our livestock industries. I sense that too many of us are using too many drugs too often, and obviously, unnecessarily in some cases. It is better to have a plan to try to manage and out-manoever disease problems rather than relying primarily on antibiotic treatments. We can take the approach of medicating with antibiotics only when necessary, and then use management strategies that could include those outlined in this article, among others, to stay ahead of disease, or to say it another more positive way, to promote good health.

Gordon Chalmers