E. coli Infection in Pigeons

E. coli Infection in Pigeons

by Steve Weir, DVM

E. coli infection in pigeons is caused by the bacterial Escherichia coli. This bacteria is very common world-wide, is closely related to other intestinal bacteria such as Salmonella typhimurium (the bacteria that causes paratyphoid), and commonly inhabits the intestinal tract of mammals and some birds. It is considered a NORMALinhabitant of the intestinal tract of all pigeons, and simply finding this organism on a fecal culture should be no cause for alarm. As an aside – this is not a normal bug in parrots and some parrot veterinarians are not aware that E. coli is normal in pigeons.

E. coli has been shown to be the cause of disease in many species of animals including humans. The symptoms vary from species to species but intestinal upset is pretty common no matter who is having an E. coli problem – animals, birds, or man. This bacteria has many different “strains” that infect our pigeons that vary immensely in their ability to cause disease. These strains are called “serotypes” and can be differentiated by special laboratories with testing for that purpose. Some serotypes can easily cause disease while others are harmless to our birds (the ones that are found normally in all pigeons). The ability to cause disease by a serotype of E. coli is called pathogenicity and is related to:

1) The ability to produce toxins. Some serotypes of E. coli produce endotoxins which can produce serious illness and death in our birds. I personally feel it is these endotoxins which severely hamper performance on race day in some lofts.

2) The ability to invade past the intestinal wall and cause infection in other organs such as the oviduct and liver. Some serotypes of E. coli are really good at getting into various organs in our birds instead of staying in the intestine where they belong.

3) The ability to overcome the pigeon’s immune system. Some E. coli serotypes have the ability to avoid some of our pigeon’s immune defense systems and thus produce disease more readily than other serotypes.

Infection with E. coli can be classified as primary or secondary. Primary infection means the serotype is able to produce disease without a lot of underlying problems – and some serotypes certainly can do this. Secondary E. coli infection means that the serotype only becomes an issue when other predisposing factors are present. In other words – there is some underlying cause for the infection. Most E. coli infections are secondary and the underlying stress that leads to the problem includes things like a heavy molt, coccidia, adenovirus, canker, intestinal worms, crowding, heaving training and poor nutrition. Because most of the E. coli problems in lofts are usually secondary, it is critical to look for an underlying cause when E. coli is diagnosed in your birds.

When we diagnose E. coli disease (remember – not the same as just finding the bug on culture because all birds have the organism -just a non-pathogenic serotype), we do so based on a number of symptoms in your pigeons coupled with finding the organism. E. coli disease produces a group of symptoms in our birds and you may have all or just one of these in your loft. Interestingly, they are very similar to the symptoms caused by paratyphoid – another intestinal bacteria that causes disease (and is never supposed to be

your birds). I often begin to suspect E. coli disease when I start to see various symptoms show up in someone’s loft. These symptoms include:

Enteritis: This is the most common of the problems we see with E. coli and shows up as loose green droppings. Pigeons that are typically affected with be young birds (stressed with the molt, growing, training, etc.) and many of them will also vomit up grain. Slow crop emptying is a huge red flag for E. coli problems. When you go in the loft in the morning to crate your young birds they should have empty crops from the night before. If many of them still have grain in their crops – especially if you find loose green droppings and vomited up grain on some perches – E. coli disease is at the top of the list.

Sudden death: Sudden death in any age bird – often with no previous signs – is very common with E. coli disease. We also see this with paratyphoid and Streptococcus infections so cultures are critical to make sure it is E. coli. This is due to a sudden increase in bacterial numbers and high levels of endotoxins in the bloodstream – which are fatal to pigeons (same reason we get sudden death with paratyphoid and

Streptococcus). In my practice one of the most common things I see with E. coli disease are youngsters dying suddenly in the nest about banding age. They will be full of grain and just dead for no apparent reason. If I culture almost any organ in one of these dead youngsters it will yield high levels of E. coli. The age this gets them correlates with the decrease in immunity that they received from the egg and crop milk.

Fertility problems: Although E. coli can cause fertility problems in both sexes, the hen is most often affected. E. coli can cause an oviduct infection in hens – even young ones. Typically, we will see young hens on the second or third round of eggs, spread out like they are going to lay, set the nest, and never actually produce an egg. Some will go ahead and lay but the egg will be soft, rough, or small. Eggs that are fertile will often die once incubation has progressed a few days due to bacterial growth in the egg. When I culture these eggs I will grow E. coli. When I have had hens that I suspect of having an E. coli problem, I will culture their droppings and grow the E. coli in their intestines – it will be the same one that is in the oviduct. I will then do a sensitivity to determine which antibiotic works best and try to find one that works and is safe to use when she is laying (try to avoid baytril or cipro). I will then place her on the appropriate antibiotic for several days before mating up, and keep her on the drug until she lays her eggs. I then take her off. I have had good success doing this for many hens and fanciers were able to get healthy, fertile eggs that hatched with no problems.

Joint infections: E. coli, not as often as Salmonella (Paratyphoid) however, can cause joint infections which cause lameness or a dropped wing. Swelling may or may not be seen in the affected joints. Treatment with the appropriate antibiotic is very helpful.

Respiratory infection: E. coli can infect the respiratory tract along with the other typical causes of respiratory infection such as herpes virus, Mycoplasma, Chlamydia, and other bacteria. E. coli is not a normal inhabitant of the respiratory tract of a bird, so whenever we culture it from that location it must be treated with the appropriate antibiotic. Symptoms of infection with E. coli in this location results in severe respiratory signs such as exercise intolerance, open mouthed breathing, and rattles.

Paralysis: One will often find a bird in the loft lying on the floor unable to use its legs it appears to be paralyzed. When the cause is E. coli it is due to an overwhelming infection with endotoxin production. This is a very serious sign, is typical with E. coli infection (or salmonella – paratyphoid), and must be treated immediately because death is near for these birds.

Poor performance: This symptom is one that I am beginning to consider a big one in many lofts. We know that E. coli is an endotoxin producer – some strains more than others. These toxins can make birds obviously sick in large amounts, but I feel many birds have a level of infection that doesn’t make them terribly sick, but does cause them to feel bad enough to perform poorly. I have seen several lofts that have had performance problems and in general the only thing we could find wrong was a high level of one of the “bad” E. coli bacteria in the droppings. Many times the birds had pretty normal droppings and no other symptoms related to E. coli disease. Now, these lofts were All American and President’s Cup winners – they know how to fly – lest you think the problem is the handler. When we treated with the proper antibiotic, performance dramatically increased, but when the antibiotic stopped, performance dropped again in a week or two. On reculture the E. coli level was high again. My thought is that the way we fly pigeons today tends to predispose them to E. coli overgrowth because of:

1) Stress – especially in young birds – we train their feathers off during the week, race them weekly, expect them to grow and molt, and add other types of stress.

2) Other diseases – All of the other bugs we see such as canker, coccidia, and worms predispose our pigeons to E. coli overgrowth.

3) Medication – All of the medication that we use to control other diseases really takes a toll on the normal bacteria in the intestine, thus predisposing them to E. coli overgrowth.

The fact that appropriate (one that was shown to work on their serotype) antibiotic therapy for E. coli greatly improved performance made me think that by controlling the

E. coli level we might really be on to something. So, in several lofts with the problem, I made them an autogenous vaccine for E. coli (one that was made from the E. coli in their loft). We had them vaccinate their birds twice with this vaccine. In almost every case performance drastically improved to championship levels and we were able to almost completely quit using antibiotics for E. coli overgrowth. You need to recognize that I haven’t done “scientific studies” to prove this, but from my observations of the results we have achieved this could be a real key for some lofts.

When we diagnose E. coli it is critical to remember that we cannot do it on symptoms alone – since other bacteria like Salmonella (Paratyphoid) cause the same set of problems. When we suspect E. coli we culture the droppings and organs of an infected pigeon. When found, we run a sensitivity test to determine which antibiotic works on the serotype we found. THIS IS CRITICAL AS E. COLI VARIES TREMENDOUSLY AS TO WHICH ANTIBIOTIC KILLS IT. E. COLI DEVELOPS RESISTANCE VERY QUICKLY TO VARIOUS ANTIBIOTICS AND YOU SHOULD NEVER ASSUME THAT WHAT WORKED ONE TIME WILL WORK THE NEXT TIME.

Treatment of this disease involves 3 areas:

1) Antibiotics used for 7 – 10 days: It is critical to have a sensitivity test ran as we pointed out earlier as E. coli is resistant to many drugs. A “shotgun” approach rarely works – even the “invincible and revered baytril” doesn’t work in many cases. When an antibiotic works the following are the correct doses:

Amoxicillin: 1500 – 3000 mg/gallon.

Baytril or Cipro: 250 mg/gallon for baytril and 750 mg/gallon for cipro. Do not use during the breeding season – especially when the egg is being formed.

Primor: 1200 mg/gallon.

Cephalexin: 2500 – 3000 mg/gallon.

Neomycin 325 -l/2 teaspoon/gallon.

2) Treatment of any underlying causes: If you do not get rid of the underlying causes that are causing the E. coli to show up – it will be back sooner than later. Make sure you control all of the stuff we discussed earlier.

3) Vaccination: This has been extremely helpful for some lofts and has really boosted their performance. It may be the treatment of choice in the future. At this time I am not recommending vaccination for lofts with no E. coli symptoms. Remember -just growing the bug is no big deal – all birds carry some serotypes of E. coli. It is only those nasty serotypes we need to worry about. So don’t think you can talk me into making you a vaccine and you will top the sheet every week. Vaccination is great if you need it – no help if you don’t.

Good luck and happy flying – Dr. Steve Weir, DVM Steve Weir, DVM