Salmonella
Paratyphoid is one of the most familiar and important diseases for pigeon fanciers. Paratyphoid is caused by a bacterium called Salmonella. This is a disease that has been with pigeon fanciers since pigeons were first kept and yet, even in recent years, this problem is still revealing some of its secrets to us. Much of our understanding and knowledge, diagnostic methods and treatments have changed in the last ten years. This chapter is a summary of current knowledge about this disease and includes the current diagnostic techniques and recommended treatments.
Nature of the disease
Paratyphoid affects pigeons world-wide. All types of domestic pigeons can be affected. Salmonella, however, at least in Australia, appears to cause clinical disease in fancy pigeons more commonly than racing pigeons. Some breeds of fancy pigeons seem particularly susceptible – in particular Modenas, show homers and the performing flying breeds such as tumblers, tipplers and rollers, but particularly Doneks.
The outcome of exposure to Salmonella is very much affected by factors relating directly to the individual pigeon. These factors include its age, general health, level of nutrition, paratyphoid vaccination status, genetic make-up and whether it has had any earlier exposure to the disease that might have enabled it to establish some nature immunity. As a general rule younger pigeons are more susceptible to clinical disease.
Management and environmental factors that compromise the general health of the birds, such as over-crowding, poor diet and concurrent parasitic infections, all compromise the birds’ ability to resist infection and increase vulnerability to clinical disease. Infected birds shed Salmonella in their droppings and the bacteria, once in the loft environment, can survive and multiply. Poor hygiene, in the form of accumulated droppings in the loft and also feeding and watering practices that allow for dropping contamination of food and water, not only compromises health generally but provides high exposure to the organism.
Salmonella bacteria survive particularly well in the loft environment if it is warm and damp. Severe outbreaks of clinical disease can occur if there is high exposure to the organism in a group of pigeons which have a reduced ability to fight the infection due to poor management practices or a poor loft environment.
In pigeons, the disease can take several forms:
1. In young pigeons the usual form is the ‘bowel form’ of the disease. In young pigeons, after ingestion, the bacteria multiply in the bowel, causing enteritis that can be fatal. This is the classic ‘going light’ when birds develop weight loss, lethargy, green diarrhoea and loss of appetite, sometimes leading to rapid death. This is the usual form seen in very young pigeons but can occur in older pigeons with an impaired ability to fight infection.
2. Older birds (i.e. over three months of age) are more likely to survive bacterial replication in the bowel but the bacteria can then penetrate the bowel wall, enter the blood stream and then be carried throughout the body. Signs displayed by infected birds depend on where the bacteria localise.
Common sites of infection are:
a. The Meninges – leading to the meningeal form of the disease. The meninges are the membranes surrounding the brain. When the meninges are inflamed this interferes with the brain’s function so that the bird may be poorly co-ordinated, hold its head in an unusual position or show paralysis.
b. The Joints – leading to a Salmonella bacterial arthritis. Affected joints in the wings and the legs become red, hot, painful and swollen. The infection can erode cartilage from the joint surface and cause extensive damage to the joint generally. A delay in the onset of treatment may mean the joint is left permanently damaged.
c. The Gonads – where affected birds often look remarkably well, with the infection only becoming obvious at the next breeding season. Hens with infected ovaries often have late or irregular ovulations or no ovulations at all. Salmonella can be incorporated in the egg at the time of its formation in infected hens. The bacteria then infect the developing embryo. Embryonic death can occur (usually in the mid third of incubation). If the chick survives through to hatching, it may hatch in a weakened state, dying in the first two weeks of life. In young cocks with infected testes, Salmonella is a cause of premature infertility.
d. Multiple Organs – here the bacteria become widely distributed throughout the body, localising in many organs, which may include the liver, kidney, spleen and respiratory system. Pigeons with this form of the disease present as very sick pigeons. They are often hunched, fluffed, not eating, have green mucoid droppings, rapidly lose weight and may die, often quite quickly.
Despite the severity of symptoms sometimes displayed by infected birds, all birds are worth treating. The main factor determining whether or not a successful outcome is achieved is the time between diagnosis and starting the correct treatment. A delay often gives the disease too much of a head start.
Birds with the meningeal form of the disease may be so poorly co-ordinated that they need to be hand fed. However, brain infection in birds always carries a much better prognosis than in mammals. In mammals, function returns after brain injury because adjacent areas of brain tissue learn to take over the function of the damaged area. Birds, however, have stem cells in their central nervous system, which give them the ability to actually regrow damaged areas of brain.
When in the joint, the infection can quickly damage the cartilage surface. Even with successful treatment, this rarely heals perfectly, leading to joint pain on exertion. The prognosis for subsequent racing is guarded but these birds can be retained for breeding. Both the testes and ovary are fragile organs and a delay in treatment can lead to permanent damage and a reduction in fertility.
When pigeons are exposed to Salmonella, a variety of outcomes can occur. Some birds may clear the organism from their system without becoming unwell. Some will become sick. Even with effective treatment and apparent recovery, not all birds will clear the organism from their system. Birds that appear normal but are carrying the infection in their bodies are called asymptomatic carriers. We now know that these are the main source of infection. These carrier birds intermittently shed the organism in their droppings. Further birds become infected, typically through ingesting food or water contaminated with these birds’ droppings. Asymptomatic carriers, although carrying the organism in their system, may appear completely normal or, at most, only show mild symptoms such as intermittent diarrhoea or, perhaps even more subtly, reduced race performance or reduced reproductive ability.
Species Specific
A common belief among fanciers is that if some birds are unwell and there is evidence of rodents in the loft, then perhaps their birds could have paratyphoid. Until recent years, standard knowledge throughout the veterinary and pigeon community was that paratyphoid in pigeons was caused by the bacterium Salmonella typhimurium. This species of Salmonella was regarded as a widespread organism in nature. It was thought that the variety that infected pigeons also infected many other animals, particularly rodents. After all, the organism’s name ‘typhimurium’ literally means ‘typhoid of mice’. It is now thought that infection through rodents is unlikely.
We still have a lot to learn, but our understanding of Salmonella infection in pigeons has changed over the past few years. Today’s technology enables us to type various strains of Salmonella very specifically. The Salmonella strains that can cause clinical disease in pigeons can be identified right down to the phage type. It is thought that these phage types are likely only to cause disease in pigeons. This means that Salmonella strains found in other animals such as wild birds, chickens and other mammals, including rodents, do not cause disease in pigeons.
It seems likely that Salmonella in pigeons is a pigeon-to-pigeon disease, the source of infection being asymptomatic carrier birds or their droppings. Non-infected birds can be exposed to asymptomatic carriers in the race basket or in the home loft if carriers are introduced by the fancier.
The Infectious Organism
The actual type of Salmonella that infects pigeons has been identified as Salmonella enterica, subsp. enterica, serovar typhimurium, variant copenhagen, Anderson phage types DT2 and DT99. The available evidence suggests that disease in pigeons is caused by these serotypes. Evidence also shows that these types are isolated extremely infrequently from species other than pigeons. Further research is expected to show that these types are in fact what is called ‘host adapted’, having evolved with the pigeon and only capable of infecting it.
Other Salmonellas can occasionally be isolated from the droppings of pigeons, but it is thought that these are simply transients accidently ingested by the bird and passing through the system but not capable of causing disease. Many pigeon fanciers who currently believe that pigeons catch Salmonella from rodents will need to alter their way of thinking as we now know that this is not the case. Several other species of Salmonella are also known to infect only one species. Examples include Salmonella gallinarum that only infects chickens (causing Fowl Typhoid) Salmonella dublin (that only infects cattle) and Salmonella choleraesius (that only infects pigs).
Ramifications
The knowledge that the variety of Salmonella that causes clinical disease in pigeons is species-specific for pigeons has two immediate ramifications:
1. Zoonoses – historically pigeons and their droppings have been regarded as a potential source of Salmonella infection in humans. Obviously this belief needs to be reviewed.
2. Import requirements – currently in Australia there are periodic outbreaks of paratyphoid in legally imported pigeons whilst in quarantine. The Government tests this Salmonella and when identified as Salmonella typhimurium, a strain regarded as endemic in Australia, the birds are still allowed entry into the country.
The aim of quarantine is to prevent the introduction of exotic disease. Thus, detecting the presence of a disease already known to be in Australia is not a reason to halt release of the birds. Given the current technology, this protocol perhaps needs to be revisited to ensure that these strains are in fact not exotic to Australia. Salmonella in pigeons in Europe (the source of most import birds) behaves quite differently from Salmonella in Australia.
Given the current protocol there is the potential to introduce new Salmonella strains with different drug resistances and clinical characteristics, etc. The Government has suggested that it is up to the pigeon community to present evidence to them as to why the protocol should be changed but, of course, most pigeon fanciers do not want the protocol changed; they just want to get the birds, even though they run the risk of getting a new exotic Salmonella variety. At the moment, it appears the current situation will continue until there is some disease disaster, at which time there will be a lot of finger pointing.
As our knowledge continues to evolve over time, Salmonella will become more fully understood but, as it stands at the moment, it seems that pigeons carry very distinct varieties of Salmonella; it is only certain phage types that cause clinical disease in pigeons. These phage types do not cause disease in other animals and can be carried totally asymptomatically by carrier birds. The standard belief that, particularly in pigeon lofts, exposure to rodents and, to a lesser extent, other animals and birds is the usual source of Salmonella is no longer accurate. The likely source of infection is chronic asymptomatic carrier pigeons.
Managing Salmonella in the loft
The aim of any pigeon racer is to keep the stock birds healthy and in breeding condition and to field successful race and show teams. As paratyphoid can adversely affect all of these, it is obviously important that the disease is correctly managed. The initial aim ideally should be to keep the organism out of the loft. However, this ideal is difficult to achieve, given the nature of pigeon racing and showing where many birds from many lofts intermittently mix. Some fanciers accept introduction of the organism as inevitable, so for them the aim then becomes doing what can be done to protect the birds and minimising the impact of the disease should it gain entry.
Treating the Disease
Treating paratyphoid involves several steps.
1. Accurate diagnosis. Make sure the problem is actually Salmonella. Don’t jump to conclusions. The symptoms of Salmonella infection resemble those of other diseases. Don’t make an intelligent guess by yourself based on symptoms. In particular, not all ‘dead in shell’ youngsters are due to Salmonella; in fact most are not. There is the potential to waste both money and time on the wrong medications and approach while the real cause of the health issue just becomes more established. Consult an avian vet and get an accurate diagnosis.
2. Effective antibiotic treatment. Once Salmonella has been diagnosed by your vet it is always best to have the actual strain identified in your birds tested by your vet’s lab against a number of antibiotics to see which antibiotic is most effective at treating it. This test is called a micro, culture and sensitivity test (abbreviated to mc and s) and is surprisingly economical.
With today’s multi-resistant strains of Salmonella, it is possible to spend a lot of money and put a lot of effort into using an antibiotic that just will not work. Don’t be cheap. Have the testing done. That way you will be confident that the antibiotic you are using will be effective in your loft. Most common Salmonella strains are sensitive to either the fluoroquinolone antibiotics (for example, enrofloxacin) "Baytril" or sulphur-based antibiotics (for example, trimethoprim/sulphadiazine, "Sulpha AVS"). Some are sensitive to tetracyclines (e.g. doxycycline). Few are sensitive to the penicillins (for example, amoxicillin). Once the antibiotic to be used has been selected, this needs to be given as a long course. Treatment times of 10 to14 days are usual.
3. Thorough cleaning. While the antibiotic course is proceeding, the loft needs to be thoroughly cleaned. A diagnosis of Salmonella is one of the few indications for actually wetting the loft with a disinfectant. Choose the morning of a warm day. Thoroughly clean the loft. Move the birds out. Spray the diluted disinfectant (for example, "F10" or "Virkon") on to the scraped surface and into the nooks and crannies.
Another disinfectant agent recommended by vets is chlorine dioxide. A common brand name is "Oxine A.H." This is useful to help control not only bacterial but also viral problems. When using this, citric acid is added to make ‘activated oxine’. The resultant solution will turn yellow and give off a faint odour of chlorine. This is diluted in water 5 ppm for the drinking water and 200 ppm for loft fogging (e.g. with a ‘Fog master’). After adding water the solution can be used for seven to ten days and does not lose potency. The birds can be left in the loft during fogging.
4. Providing ongoing good care. Birds that are rundown cannot mount a good immune response. Part of the job of clearing any infection comes down to the pigeon’s immune system. This needs to be in good shape. Ensuring the birds are well fed, kept clean, not overcrowded, have good parasite control and are in a loft that is warm, well ventilated and dry sets the stage for the immune system to work well and help clear the infection. Poor care will interfere with the bird’s ability to recover. Thorough veterinary testing will reveal any other concurrent health issues that need to be addressed. General management and the loft environment should be reviewed.
Diagnosing the disease
It may seem obvious, but basically paratyphoid is diagnosed by identifying the presence of Salmonella bacteria associated with disease. It is important to remember that strains of Salmonella can be transiently present within the digestive tract and found in the droppings of pigeons. Simply detecting the presence of Salmonella here is not a diagnosis of paratyphoid. One needs to identify the particular type of Salmonella capable of infecting pigeons and associate this with an actual infection. Paratyphoid can be diagnosed in a number of ways. The two common ways are:
1. Bacterial culture. Your vet can collect a swab from a suspect site internally from a dead bird during autopsy or in a live bird from the cloaca, throat, droppings or surgery site. Once collected, the bacteria on this swab, be they Salmonella or not, can be cultured (i.e. grown) identified and, ideally, also tested against a number of antibiotics to see which is the most effective. In pigeons, growing Salmonella from any site outside of the bowel is always a diagnosis of paratyphoid.
When Salmonella is identified within the bowel or droppings, in order to ensure it is not a transient, it needs to be associated either with clinical symptoms associated with infection of the bowel (for example, persistent diarrhoea) or, alternatively, inflammation of the bowel identified through histopathology (microscopic examination by a pathologist). Histopathology, although very accurate, has the disadvantage of taking up to a week to do and can be moderately expensive.
2. Antigen detection test or QUICK test. In a simple test with a long name (sandwich lateral flow immunochromatographic assay) protein on the surface of the bacteria can be detected. Again, a sample is collected either during autopsy or from a live bird. This sample is mixed with an extraction fluid, the resultant supernatant is dripped on to a test paper and a colour change occurs if the Salmonella protein (or antigen) is present. Quick and easy, this test is comparatively inexpensive and takes under 10 minutes to perform. The ability of this test to give a quick answer is a great advantage, particularly during the racing season, where starting accurate medication promptly allows a quick return to competitive racing for the team.
The manufacturer AvianLabs instruction sheet explaining how to perform the test is reproduced below.


Common Ways of Reaching a Diagnosis
1. In a group of utility, exhibition or racing pigeons. In a group of pigeons displaying symptoms consistent with paratyphoid, a cull bird that is representative of the group is selected and euthanased. This bird must be a typical member of the group so that its results can be realistically extrapolated to the group as a whole. Within four hours of death the bird is autopsied. This time limit is important as tissue breakdown and invasion of decomposition bacteria occur if done after this time. Tissue samples are collected for histopathology (staining and microscopic examination) and swabs are collected from potential sites of infection for bacterial culture. These tests, although very thorough and accurate, have the disadvantage of taking up to a week to get results and can be relatively expensive.
2. In a race team during the season. A bird may not be available for euthanasia. In race teams during the race season symptoms can be very subtle. Performance may be below expectations. Individuals may intermittently have diarrhoea. Other tests for disease may be negative. Detecting Salmonella consistently in the droppings (by culture or QUICK test) may warrant a treatment trial on an appropriate antibiotic. A good response to treatment is suggestive of paratyphoid.
3. In the breeding loft. Breeding birds with poor reproductive performance can be anaesthetised and an endoscope inserted through a keyhole incision in their left flank to examine the gonads. During examination a swab can be collected directly from the gonad for bacterial culture or QUICK test. Identifying Salmonella enables a diagnosis of paratyphoid and identifies the cause of the reduced fertility. Fertile eggs that fail to hatch can be autopsied and samples collected for culture, a QUICK test or histopathology.
4. In birds with the joint form of the disease, a sample of joint fluid can be collected in a technique called a FNA ( fine needle aspirate). The sample can be submitted to the lab for culture or have a QUICK test performed on it.
Difficulty In Treating the Disease
If paratyphoid is identified in the loft, it is a very difficult disease to eradicate, for several reasons:
1. Problems with antibiotics. Salmonella, being a bacterium, can be treated with antibiotics. Effectively treating Salmonella with antibiotics is, however, difficult. This is because: a. Salmonella has a very particular characteristic shared by only a small number of bacteria. One of the ways the body protects itself from bacterial infection is through a process called cell mediated immunity. In this process, white blood cells act like little ‘Pacmen’ engulfing bacteria. Most bacteria, once engulfed by a white blood cell, are digested by that white blood cell. However, Salmonella, after being engulfed by a white blood cell such as a macrophage, can survive within that white blood cell. Once there, the Salmonella cannot be reached by antibiotics, being protected by the white blood cell. With the death of the white blood cell the Salmonella are re-released into the system.
b. Salmonella bacteria in an infected bird are widely distributed throughout the body in the blood stream. At some sites, small pockets of infection called abscesses form. These abscesses become surrounded by walls of scar-like tissue as the body tries to protect itself. Salmonella in these abscesses can survive antibiotic courses and ‘seed out’, back into the system once antibiotic courses end.
c. Pigeon fanciers and vets overuse and misuse antibiotics, often treating Salmonella infections with inadequate doses and courses which are too short to effectively kill all organisms. The tougher, harder-to-kill strains are left behind. These ‘resistant’ strains make it harder and harder to successfully treat subsequent disease outbreaks.
2. Salmonella can survive and multiply in the environment. Even if antibiotic courses were able to completely clear the organism from an infected bird (and they still do this when used correctly, in most birds) unless the environment is correctly cleaned the birds become reinfected from that contaminated environment. It is worth commenting here on the old practice of using lime in pigeon lofts. Lime, apart from creating a dust aerosol when the pigeons fly that irritates the birds’ lungs and air-sacs, creates an alkaline environment in the loft. Salmonella actually prefer an alkaline environment to survive. These days, fanciers should use a proper disinfectant that is registered for this purpose. They are cheap and readily available. Examples include F10 and Virkon.
Carrier identification
A major challenge with long-term control is the detection of persistent carriers after treatment. A successful treatment is one where the infection is cleared from over 90% of birds. Because of the difficulties associated with treatment, some birds will continue to carry Salmonella after treatment. These birds can subsequently, particularly if stressed, shed Salmonella, re-contaminating the environment and reinfecting successfully treated birds.
Repeat treatments are sometimes necessary. There is no fool-proof way of identifying carriers, although repeat cultures and QUICK tests on individuals can be done. Birds, particularly valuable birds that continue to show symptoms or relapse after treatment, can be repeatedly treated in isolation. Some fanciers prefer to cull persistent carriers. Actually detecting Salmonella in all carriers is virtually an impossible task and some birds deemed to be successfully treated will in fact still have the organism in them. Unidentified carriers remaining in the loft is the most common reason for treatment failure.
Keeping The Disease Out Of The Loft
Because of the difficulties involved in treatment and successfully eradicating the organism once established in the loft, an effort should be made to try to stop the birds becoming infected in the first place. As mentioned earlier this can be hard in the racing loft because of the large proportion of the loft’s inhabitants leaving the loft, mixing with birds of other lofts, and then returning on a weekly basis. In the stock loft bird movement is less and although no method is fool-proof, some measures will decrease the chance of Salmonella gaining entry. Ideally, only obtain birds from lofts (including studs) known not to have a problem with Salmonella. New birds should be regarded as potential sources of the disease. Under stress carriers may shed the organism in their droppings where it can be detected. Veterinary examination of the droppings at other times may give a negative result even in a bird carrying the disease.
Quarantining birds (usually for about six weeks) is a good idea. Any birds that occasionally become quiet and develop greenish diarrhoea during quarantine should be suspect. As stated above, there is no fool-proof way of preventing Salmonella entering the stock loft but being selective about where new birds come from, applying a quarantine period and monitoring and testing during this time will all minimise the risk. A further and important way of preventing Salmonella becoming established is vaccination.
Decreasing the incidence of disease if Salmonella enters the loft
Vaccination
In various countries, paratyphoid vaccines are available. Some are better than others. The modern vaccines confer good immunity against the known disease-causing strains of Salmonella and fanciers should take advantage of them when they are available. Each brand comes with its own manufacturer’s instructions. These should be followed. The usual recommendation is to vaccinate twice in the first year of life, often at a three to four week interval, and then give annual boosters.
Often boosters are timed to be given before times of anticipated high exposure (such as just before racing) or just before a time of anticipated stress (such as just before breeding). It is not unusual to give 10 to 14-day courses of antibiotics before vaccination to clear any latent infections from as many birds as possible and then vaccinate them before they are re-exposed. Vaccinating carrier birds does no harm and may be beneficial but will not clear the bacteria from these birds.
In Australia Dr Mark White and his company Tréidlia Biovet make a killed Salmonella typimurium vaccine for pigeons based on Australian pigeon isolates. The vaccine is given as a 0.3 mL injection subcutaneously. The recommendation is that young birds are given at least two doses. The first dose is given around the time of weaning and the second 3-6 weeks later. Sometimes a third dose, around two weeks prior to the racing season, is given. In the first year of vaccine use, breeders are given two doses 3-6 weeks apart with the second dose given around two weeks before birds are paired. In subsequent years the breeders are given a single injection about 2 weeks before pairing. More information can be found at www.treidlia.com.au
Management
Caring for the birds as well as you can creates a situation where the birds are more likely to resist infection if they become exposed. Even so, the birds should be monitored for symptoms consistent with Salmonella and if a fancier becomes suspicious, their cause should be promptly investigated by a veterinarian (hopefully before the disease becomes established).
Prophylactic Treatment
In many countries, Salmonella vaccines are not available. In some lofts the disease has already been diagnosed (for example, in a previous racing or breeding season) and is proving difficult to eradicate. Sometimes fanciers are concerned that there may be undetected carriers in the loft. Because of the ongoing mixing of birds during racing Salmonella exposure is always a possibility. In situations like these, your veterinarian may recommend prophylactic preventative treatment for Salmonella in an effort to head off a potential flare-up of paratyphoid. Two common times for this to be done are:
1. Before Breeding. If Salmonella has been diagnosed as a cause of late or irregular laying in the hens, embryonic deaths, reduced nestling viability or death, premature infertility in cocks, etc., in a previous breeding season, then rather than wait for similar problems to re-occur your vet may recommend treating the birds with an appropriate antibiotic such as "Sulpha AVS" for 10–14 days, finishing two to three weeks prior to pairing.
This is not an attempt to eradicate the disease, but rather an effort to reduce the level of Salmonella in the stock loft as a whole so that the disease is less likely to have an impact once breeding has commenced. The 2–3 week break between treatment and pairing enables tissue healing to occur at previous sites of infection and allow normal bowel populations of bacteria to re-establish.
Probiotics on the food or in the water after the antibiotic course is completed will help with this process. Multivitamin, mineral and amino acid supplements are also useful during this time to build the birds up ready for breeding. This treatment should be combined with a thorough clean of the loft.
2. Prior to Racing. As with the stock birds, a 10–14 day course of an appropriate antibiotic as indicated by your vet can be given to the race team finishing two to three weeks prior to racing. During the racing season the birds are likely to be exposed to Salmonella in the race baskets. Starting the season with healthy birds, controlling other diseases throughout the racing season and maintaining ongoing hygiene and general good care should minimise the impact of exposure.
If the disease does gain entry to the loft and cause clinical disease during the season this is serious. Unless detected very early, ideally racing should be stopped and an effective long (ten days plus) antibiotic treatment (antibiotic choice determined by testing) given and racing only resumed when the problem has resolved.
The protocol, followed by some fanciers, of giving short antibiotic courses (two to three days) intermittently through the season to prevent/treat this condition is a waste of time and only encourages the development of resistant Salmonella strains and asymptomatic carriers. It is also thought that these short courses may actually increase the incidence of the disease over time in another way – by continually disrupting the population of normal bowel bacteria which help to protect the bowel from Salmonella invasion. Where paratyphoid vaccines are available fanciers should vaccinate their birds prior to racing. When Not To Treat
There are times when prophylactic antibiotic courses should not be considered.
1. During Breeding. Antibiotics disrupt the normal population of bowel bacteria. These bacteria are necessary for nutrient absorption and digestion. Their role is particularly important in young growing birds. Antibiotics therefore have the potential to compromise the growth of nestlings. During breeding there are also difficulties in effectively dosing all of the birds in the loft. For antibiotic courses to be effective all birds in the loft need to get their dose. When antibiotics are used in the drinking water during breeding, the parents drink the water and get a dose. By the time they feed their young chicks they have absorbed this and the chicks get none. When medication ceases the chicks then reinfect the parents. Little has been gained.
2. During Moulting. Because of their effect on the bowel bacteria and resultant interference with nutrient absorption, antibiotics, when used for longer treatments during the time of feather growth, can adversely affect both the structural quality and pigment deposition of feathers.
3. With Young Growing Pigeons. These birds need exposure to potentially harmful bacteria (and other organisms) periodically at non-disease-causing levels during growth to develop their natural immunity. Antibiotics interfere with this.
During these times antibiotic treatment would usually only be recommended in the face of a Salmonella outbreak. In this situation we choose to risk side effects for the definite benefit of treating active disease; otherwise Salmonella antibiotic treatments should be avoided.
Health Programmes to Control Salmonella – Summary
In the race loft
1. When vaccines are available, vaccinate all birds following the manufacturer’s recommendations. Usually this involves two vaccinations three to four weeks apart initially, followed by annual boosters. Time annual boosters to be given six weeks before racing starts (time of high exposure).
2. If the loft has a history of Salmonella give Sulpha AVS for 10–14 days, finishing three to weeks prior to racing.
3. Maintain good management practices and a good loft environment. Management flaws such as overcrowding, poor hygiene and poor control of parasitic disease weaken the birds and predispose them to infection.
4. If an outbreak occurs during racing then, if less than 3% of birds are affected, separate these and treat them with an appropriate antibiotic. Baytril 2.5%, 0.5ml per bird per day for 10 days or 10mls to 1 litre, or Sulpha AVS 3gms to 4 litres are common choices. Disinfect the loft and treat in-contact but still healthy birds with probiotics. If more than 3% of birds are affected, suspend racing. All birds should be given a 10 day course of an appropriate antibiotic during which time the loft is thoroughly cleaned and disinfected with Virkon, F10 or Oxine AH. Only resume racing when the problem resolves. Samples can be tested as treatment comes to an end to see if the paratyphoid has cleared or the course needs to be continued.
In the racing stock loft and exhibition loft
1. When vaccines are available, vaccinate all birds following the manufacturer’s recommendations. Usually this involves two vaccinations three to four weeks apart initially, followed by annual boosters. Time annual boosters to be given six weeks before racing starts (time of high exposure).
2. If the loft has a history of Salmonella give "Sulpha AVS" for 10–14 days, finishing three to four weeks prior to racing or showing.
3. Maintain good management practices and a good loft environment. Management flaws such as overcrowding, poor hygiene and poor control of parasitic disease weaken the birds and predispose them to infection.
4. If an outbreak occurs during racing then, if less than 3% of birds are affected, separate these and treat them with an appropriate antibiotic. "Baytril" 2.5%, 0.5ml per bird per day for 10 days or 10ml to 1 litre, or "Sulpha AVS" 3g to 4 litres are common choices. Disinfect the loft and treat in-contact but still healthy birds with probiotics.
If more than 3% of birds are affected, suspend racing. All birds should be given a 10-day course of an appropriate antibiotic during which time the loft is thoroughly cleaned and disinfected with "Virkon", "F10" or "Oxine AH". Only resume racing when the problem resolves. Samples can be tested as treatment comes to an end to see if the paratyphoid has cleared or the course needs to be continued.
Streptococcus
Streptococcus is the name given to a group of dot-shaped bacteria capable of causing disease in pigeons. They are everywhere in the environment, mainly in the dust and air. Many species have been isolated from pigeons and they are considered part of the normal bacteria found on the skin and the lining of the digestive, respiratory and reproductive tracts. There are different types of Streptococcus that vary in their ability to cause disease. Transition from a normal bacterial inhabitant to a disease agent depends on how effectively the pigeons’ immune system is operating.
Experimentally, researchers have deliberately infected pigeons with disease-causing strains of Streptococci, both by intravenous injection and by mouth. Many of those infected by the intravenous route became sick, developing a variety of symptoms. Interestingly, however, in the pigeons inoculated with the organism by mouth, none became sick, although the organism could be cultured from the droppings or mouth of at least half of the pigeons in the month following infection. This experiment helps to explain the nature of the disease process with Streptococcus.
Pigeons are obviously being exposed to the organism intermittently, but when an otherwise healthy pigeon ingests the organism, disease is unlikely to occur. Once the organism gains entry to the blood stream, however, the pigeon can become unwell. In some studies, potentially harmful species of Streptococci have been recovered from the intestines of up to 40% of healthy pigeons. Many pigeons obviously carry these organisms without becoming sick.
As with other diseases in pigeons, there needs to be a trigger that enables the organism to invade the blood stream and spread throughout the body. This trigger can be any factor that causes the pigeon to become run down. Predisposing factors include poor management, poor loft environment and concurrent disease, but also the ability of the type of Streptococcus itself to cause disease.
Signs Associated With Disease
Once the bacteria have invaded the body of a vulnerable bird, they can spread to a variety of sites. This, together with the fact that the severity of the disease can vary, leads to a variety of symptoms that often mimic other diseases. It is therefore important that pigeon fanciers do not jump to a premature conclusion that Streptococcus is the problem with any unwell pigeons they may have.
Once the organism invades from the bowel, skin or other sites into the blood stream, it can be carried to a wide variety of sites. The symptoms displayed by the pigeons depend on the actual site within the body that the bacteria infect, as well as the severity of the infection. Disease displayed by the pigeons can be acute or chronic. Some pigeons develop a severe overwhelming disease and will die so quickly that they do not have time to lose condition. These pigeons become quiet, fluffed up and die within two to three days. Others develop a chronic, ill-thrift-type condition that may persist for as long as six to eight weeks. Some of these pigeons will recover with treatment, while others will eventually die. In some apparently recovered pigeons, relapses can occur. In still other pigeons, the disease may be transient and mild.
In some infected pigeons, the organism will localise in the respiratory system, leading to red watery eyes, a nasal discharge and difficulty breathing. In other pigeons, the liver can be affected, leading to a green diarrhoea and weight loss. In some pigeons, the heart itself may become infected. If these pigeons survive, they may develop long-term heart problems, leading to a chronic shortage of breath. The organism can also infect the membrane around the brain (leading to poor coordination, loss of balance, or a head tilt), the muscles (leading to bleeding and inflammation), the joints (leading to swollen red painful joints, in particular in the wings and legs), the kidney (leading to a thirst and excessive urination), the bowel (leading to diarrhoea), the abdomen (leading to fluid accumulation and a swollen abdomen) and testis (leading to premature infertility in young cocks).
Notably, the organism can also infect the ovary and fallopian tube of hens. This can lead to interference with ovulation, meaning that some hens will become sterile or lay eggs late or irregularly. In those that do lay, the organism can be incorporated in the egg at the time of its formation, leading to embryonic death during incubation or a weakened chick that dies during hatching or shortly after. Because the organism is found in pigeon droppings, it can contaminate the nest box and infect the healing navel of recent hatchlings.
Diagnosis
Because of the wide variety of symptoms associated with the disease, it cannot be diagnosed solely by the signs displayed by the pigeons. Similarly, the disease cannot be diagnosed through examination of the droppings as it is found there normally in many pigeons and most of these will be quite healthy. The only way to diagnose the disease is by culturing the organism from certain organs during autopsy. Swabs for culture are usually taken from the heart, brain, liver or a visible lesion.
Treatment and Control
As always, good ongoing care will mean that most pigeons are able to resist the disease and those that do get sick are in the best situation to recover. When Streptococcal disease is diagnosed, it is vital for the pigeon fancier to identify and correct the flaw in his management or loft environment that has enabled the disease to flare up in the first place. Otherwise, a poor response to any medication can be anticipated.
Being a bacterial infection, the organism responds to antibiotic treatment. So, what are the best antibiotics to use? The best way to treat is to have your veterinarian culture the Streptococcal organism involved in your outbreak and also have him do what is called a sensitivity test in order to ascertain the most effective antibiotic for that particular strain of Streptococcus. Studies show that 80% of organisms are controlled by the antibiotics amoxicillin (a synthetic penicillin) and doxycycline, while 70% are sensitive to erythromycin, 30% are sensitive to enrofloxacin ("Baytril") and only 10% are sensitive to sulphur-based antibiotics. Obviously, the two poorest drugs are "Baytril" and the sulphur-based antibiotics, so they are not likely to be the first choice for treatment of this disease (although obviously they are useful in other situations). In the absence of testing, doxycycline is the usual choice as it is equally effective as the synthetic penicillins but is more economical.
As with other bacterial bowel diseases, probiotics have a significant role to play in the control of Streptococcal infections. They can be used in times of stress, when the normal bowel bacteria are disrupted, to minimise the risk of Streptococcal invasion and also to preventatively treat healthy pigeons that have been in contact with pigeons infected with Streptococcus. Interestingly, exhibitors of fancy breeds have noticed that Streptococcal diarrhoea can be avoided in pigeons taken to shows if the pigeons are treated with probiotics such as "Probac", for several days before and after the show.
Maintenance of a clean, dry loft will minimise exposure to the organism. If necessary the loft can be disinfected. Streptococci are sensitive to most of the commonly used disinfectants. When Streptococcal infection occurs in a loft, it will spread slowly through the flock and some pigeons will start to die. When testing by your veterinarian confirms the disease, the following protocol can be followed:
1. Unwell pigeons are separated and treated with doxycycline tablets (e.g. "Doxyvet" 50 mg, ½ tablet once daily).
2. Loft cleaned and disinfected (e.g. with "F10" or "Virkon").
3. Trigger factors such as overcrowding, poor diet, low hygiene, inadequate parasite control, cold or damp conditions, etc., are identified and corrected.
4. Start in-contact healthy pigeons on probiotics.
5. If further pigeons continue to become unwell while on the probiotic treatment, then start a flock treatment of antibiotic (e.g. doxycycline water soluble powder such as "Doxyvet" 12% 3gm/2L water).
E. coli
There has been much talk over the last couple of years in the pigeon world regarding E. coli, and yet before this time it was something of which most pigeon fanciers were not aware. With this influx of information, there have been a number of misconceptions that have crept in and so, what does it mean to have a veterinarian tell you that your pigeons have E. coli, and what effect can it have on the birds’ race results?
E. coli is one of the most widely distributed organisms on the face of the planet. There are many different strains (or serotypes) of E. coli. These serotypes differ in their ability to cause disease. The big issue with E. coli and pigeons is interpretation; that is, how to interpret the finding of the presence of E. coli. The reason for this is that E. coli can be found in most normal and healthy pigeons. Leading American pigeon veterinarian Dr David Marx, former President of the American Association of Pigeon Veterinarians, guarantees that he can culture E. coli from over 90% of the best performing racers, and states that you have to interpret the finding by taking a lot of other things into consideration.
Interpretation Of The Presence Of E. coli
Just because E. coli is present doesn’t necessarily mean that it is causing disease. How do we decide? E. coli, if present, usually restricts itself to the bowel. However, some serotypes, and this only occurs with the more pathogenic (or disease-causing) strains, can spread from the bowel throughout the body and invade other organs, such as the liver. When E. coli invades the body from the bowel, it always causes disease. This means that if E. coli is found anywhere else in the body apart from the bowel, then it is definitely a problem. The problem comes if it is just present in the bowel. If the strain in the bowel is capable of causing disease, it causes enteritis.
Enteritis is an inflammation of the bowel wall. With pathogenic strains, this inflammation can be severe, leading to loss of fluid and interference with digestion. This in turn leads to a green watery dropping and an obviously unwell bird. With mild strains, the inflammation is often also mild and changes in the dropping are less marked. The droppings may remain formed but become slightly green, or have a slightly elevated water content, leading to the white component of the dropping being smeared rather than sitting distinctly and separately. Similarly, the signs of ill health displayed by the bird can be subtle and non-specific, such as cessation in the drop of down feathers or a shortening in the length of time that the birds will voluntarily spend on the wing. Just because E. coli is present doesn’t necessarily mean that it is causing disease.
Some disease-causing strains can cause disease even in the most robust birds; however, as the strain becomes milder and milder, the birds have to be progressively more and more run down until a threshold is passed that tips the balance in favour of the organism, enabling it to cause disease. Many E. coli strains in pigeons are simply opportunists, waiting to cause disease if something stresses the birds. This can be an ongoing environmental or management problem or another concurrent disease. In particular, E. coli often becomes involved with diseases that damage the bowel lining, such as worms or coccidia, and is also involved as a secondary agent with viral problems, in particular, Adeno virus.
As European fanciers in particular are aware, Adeno virus infection in pigeons is a considerable problem. A combination infection of Adeno virus and E. coli has been identified and called Adeno-coli syndrome. In the absence of bacterial infection, this type of Adeno virus causes little or no problem. In the presence of E. coli, because the Adeno virus damages the lining of the intestinal tract, the E. coli can invade and cause disease. Thus, controlling the E. coli with antibiotics makes the symptoms of Adeno virus infection decrease greatly.
Probably one of the reasons E. coli is such a common secondary invader is that it is present much more frequently. There are other bacteria that can also be opportunistic but aren’t usually present. If these were present, when the pigeon was run down or stressed, then they would potentially cause disease, too.
Problems With Diagnosis
One trap with interpretation is that, in bacterial bowel disease, the bacteria are often identified through culture. This is where the organism is actively grown in the laboratory. E. coli is very easy to grow, while other organisms that can cause similar signs, such as Salmonella, can be quite difficult to grow. This means that sometimes E. coli is given the blame when, in fact, another bacteria more difficult to culture is the real cause but is overlooked.
Diagnosis can be even more difficult or impossible when the droppings are simply examined under the microscope as a faecal smear. Bacteria occur in two common shapes, dots (called cocci) or short lines (called rods or bacilli). Different types of bacteria differ not only in their shape, but also in their size, their ability to move, and other characteristics. E. coli are mid-sized rods that are often motile (capable of movement). Some types are not. The dots, for the most part, are normal bacteria called enteric Streptococci (or Enterococci). Many of the rods are also harmless and, in fact, some are beneficial; for example, Lactobacillus.
For those with microscopes, it is easy to be mystified by the different shapes, sizes and movement when examining a faecal smear under x400 magnification. Normally, a mix of bacteria with a predominance of dot shaped ones are present. When a lot of mid-size motile rods are present these could be E.coli. If there are many dots for every short motile rod, then everything is probably okay. When the number of motile rods increases, and certainly when these become the predominant bacterial organism present, it is best to get a veterinarian to check the birds. Always, however, what is seen down the microscope must be related to what the birds are doing; that is, how they appear in themselves and what the droppings look like on the perch. Although some E. coli strains can cause disease in their own right, usually E. coli’s disease-causing capability is secondary. Its presence, therefore, should not be taken to mean disease in healthy pigeons with normal droppings. The mere presence of E. coli should not precipitate a treatment program and it is a mistake to start to treat routinely unless there is actually a problem.
Dr Marx states in one of his articles:
?Treating for E. coli which isn’t causing any problem is non-productive. In fact, we know that when we treat for E. coli, we disturb all the normal bacteria too which can make the pigeon more susceptible to invasion by various things such as E. coli when it gets repopulated as well as the other bacteria in the environment that it’s exposed to chronically. Treating for just the mere presence of E. coli is not productive and the birds will always start showing it again within a week or so after you stop treating. It’s an unattainable goal to eliminate E. coli for all practical purposes."
Treating for just the mere presence of E. coli is not productive and the birds will always start showing it again within a week or so after you stop treating.
How do we tell if there is a problem with E. coli?
• If E. coli is identified in parts of the body other than the bowel, including the crop, then this is a potential health problem that usually warrants treatment. E.coli is sometimes identified in the crop. It is not a normal inhabitant of the crop and so when identified here this is abnormal. The likely cause usually fits into one of four categories:
1. General immunosuppression leading an impaired ability to fight disease.
2. A primary crop infection.
3. Deep vomiting that brings E.coli from the bowel into the crop.
4. Food or water contaminated with E.coli either at purchase or due to unhygienic feeding practices that allow for dropping contamination.
• Identifying E. coli outside the bowel means that the bacteria have penetrated the bowel wall and have been carried by the blood to another site. In this way E. coli can infect the liver, heart, kidneys or other organs. In this situation antibiotic treatment is indicated.
• If, at any time during the year, E. coli becomes the predominant organism on microscopic examination of a faecal smear or faecal culture, and the birds are sick or the droppings are abnormal, then this warrants further investigation. A diagnosis of E.coli enteritis can only be confirmed by demonstrating inflammation of the bowel wall associated with E.coli. The solution may be a medical one or to make changes to the loft management, or a combination of the two.
• If, during the race season, changes occur in the birds, indicating a loss of form, no matter how subtle, and E. coli levels elevate in the droppings, again this warrants further investigation. The solution here is usually to make changes to the bird’s management. Probiotic supplementation is useful whilst these changes are being made.
A secondary disease associated with stress E. coli, particularly in the bowel, is usually a secondary disease. Flare-ups are often associated with some stress. There is always the possibility that a pathogenic strain could be introduced into the loft via the race or toss basket, or by a stray. This, however, does not happen commonly. Often the first thought by the fancier should be that this is probably a secondary problem. The fancier should therefore think about what has happened recently in the loft, looking for the cause of E. coli’s appearance. It is helpful to develop a checklist, noting factors that may have put the birds under stress and triggered the E. coli flare-up.
The reasons will vary from one loft to another and so the answer for each fancier will be different. In some lofts where E. coli is not usually present, its appearance may indicate a single management mistake or a recent hard toss, etc. Often the answer is self-evident. In cold-sensitive (that is, open) lofts, the problem may be intermittent and correlate with changes in weather. Here the answer may be a change in loft design. In some lofts it may be a good indicator of another disease; for example, coccidia or wet canker, so that in lofts with a known medical record the appearance of E. coli can be used to monitor the treatment and management of other problems.
In one loft, the advice may be to decrease the birds’ workload and to increase the energy content of the birds’ food either by altering the grain mix or the use of specific energy supplements, such as a seed oil supplement. In another loft, the advice may be to give two days of a canker medication followed by some multivitamins. There are, therefore, many answers, that are all correct, to solve the one problem, and the answer is not necessarily medication. If it is not possible to identify the stress factor, the E. coli will respond poorly to any medication, or quickly return once medication is withdrawn. On the other hand, if the stress factor can be quickly identified and corrected, then the lift that the birds get in overall health will often allow the birds to clear the E. coli by themselves.
E. coli is a particularly handy health monitor during the race season. Many strains rarely cause disease in their own right. The appearance of E. coli, however, particularly during the race season, may well indicate that the birds are on the verge of breaking down; that is, they are under stress. It is at this time that fanciers can use their own skills, and sometimes a veterinarian, to head off an impending loss of form.
As an example of this, I relate the following story. Recently a mixed-grain sample and droppings sample arrived at my clinic. The grain was sent for testing. All was normal except for the wheat, which was found to be heavily contaminated with fungi. The droppings contained a low but significant level of E. coli. On being told the results several days later, the fancier’s reply was that he thought the wheat was the problem. I was surprised, as the wheat, to the naked eye, looked quite okay. He stated that all he had noticed was that the birds had stopped dropping down feathers. Thinking back, he realised that the only thing he had changed was starting a new batch of wheat in his seed mix. He had already stopped feeding the wheat and feather down production had resumed. This fancier is extremely successful, and his powers of observation are probably part of the reason why. Other fanciers may not have noticed this, kept feeding the wheat, and wondered why form had trailed away.
E. coli In The Droppings
What happens if E. coli is found in the droppings? The approach differs, depending on the time of the pigeon year.
Out of the race season
If, out of the race season, E. coli is found only in the bowel, even in high numbers, then if the birds are well and the droppings look normal no treatment is indicated. One should persist with ongoing good care and have the droppings monitored. If, however, the birds are sick and E.coli is diagnosed as the problem, then the birds may benefit from treatment.
During the race season
The approach to disease is very different during the race season. The finding of a high level of E.coli in the dropping, even in birds that look well, indicates general immunosuppression. The stress that has caused this immunosuppression needs to be identified. Although the E. coli may not have started the problem, it will become part of the problem. With mild flare-ups, correcting the primary problem will lead to a boost in the birds’ health which may, in fact, resolve the E. coli flare up. With more severe flare-ups, in addition to correcting the primary problem, treatment for the E.coli may be required to return the birds to real race form.
The following approach is a common one:
• If E. coli is not normally a problem and a flare-up has occurred, review recent management practices and try to identify the trigger factor and prevent it happening again.
• If E. coli is a frequent finding, review loft-based stresses, loft design, ventilation and management practices. The loft may be too crowded, the birds may be chronically overworked, or feed quality may be poor.
• If, after review, no problem is readily apparent, then decrease the birds’ workload, increase the calorie content of the seed mix and recheck the droppings in 4 days.
• Always start the birds on probiotics. Probiotic use enhances the development of form and can be a good non-medical way of resolving an E. coli flare-up.
• Consider using antibiotics only if the birds are sick, or the birds’ droppings are poor and the above measures have not helped. Antibiotics should always be used with care, no matter what time of year. The antibiotics that kill E. coli also kill many of the normal bacteria in the bowel which are necessary for nutrient absorption and vitamin production.
If antibiotics are used during moulting, they can compromise feather quality. Incorrect use during breeding can adversely affect youngsters’ development. During racing, most bowel-active antibiotics should not be used within 48 hours of basketing. Antibiotic treatment will only prove beneficial in the longer term if underlying problems leading to stress are corrected. A common antibiotic used is trimethoprim/sulphadiazine (e.g. "Sulpha AVS").
Preventative measures in problem lofts
Most bacteria like warm damp conditions and E. coli is no exception. Humid conditions are not only stressful for the birds, but also favour bacterial multiplication in the loft environment. Humidity and loft design are discussed later in this book. Humidity can either come from inside the loft (in moisture from expired air and droppings) or from outside the loft. When the humidity is coming from outside the loft, the answer is often to close the loft in, particularly at night. When the humidity comes from inside the loft, the answer is to alter the loft’s ventilation or to decrease the number of birds kept. As E. coli is passed in the droppings, hygiene within the loft, particularly regarding drinkers and hoppers, will decrease exposure of the birds to the organism.
In numerous experiments, regular probiotics have been shown to protect the bowel from bacterial invasion and their use two days per week; for example, Wednesday and Sunday, can help protect the birds, particularly in lofts prone to E. coli problems. As E. coli is usually a secondary agent, good control of all other diseases will also decrease its incidence.