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 NORMAL inhabitant
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 blood stream - 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 that is in their intestine
- 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 DEVELOPES RESISTANCE VERY
QUICKLY TO VARIOUS ANTIBIOITICS 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 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
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