Gordon A Chalmers, DVM
Lethbridge, Alberta, Canada
E-mail: gachalm@telusplanet.net

Streptococcus bovis (now called Streptococcus gallolyticus ) is a bacterial organism that, in the past has been associated with the udder of cows ?? hence the species name bovis, in reference to bovine, or more plainly, cattle. It is also a common, normal inhabitant of the intestines of many animals, including pigeons. In dairy cattle, it is an organism that is usually a signal or marker whose presence
indicates less than optimum sanitation in the environment of the
udder. By itself, this organism is usually not important as a
cause of inflammation or infection in the udder of cattle
(although it can cause udder infections), but it does signal to
the dairy operator that sanitation around the udder of his cows
is less than desirable.

In racing pigeons, however, this organism presents a totally
different picture because it is becoming a threat to both old
birds and youngsters in some lofts in Europe. It appears that
one or more strains of this organism has adapted to cause severe
disease in pigeons, and in Europe at one point, it ranked second
in importance to Salmonella sp. (paratyphoid) as a cause of
disease in pigeons. One of the several important features of
Streptococcus bovis is its ability to mimic some of the visible
changes seen in paratyphoid infections in pigeons, namely,
septicaemia (meaning the presence of bacteria multiplying in the
bloodstream), and one of the consequences of septicaemia,
swelling of the joints when these bacteria invade the joints. As
well, differentiating between infection by Streptococcus bovis
and adenoviral infection is also difficult. Vomiting, which is
one of the main features of adenoviral infection, has not been
evident in this streptococcal infection.

In one published study, 20 cases of infection caused by
Streptococcus bovis were found among 293 submissions of pigeons
(mostly racing pigeons) to one laboratory in Europe. In 17
birds, the major finding was swelling and abscess?like changes in
the liver (strictly speaking, birds don't produce pus, so it is
not correct to call these changes "abscesses"). Swelling and
abscess?like changes were also found in the kidneys of 14 birds,
swelling of the spleen of 11 birds, enteritis (inflammation of
the intestines) in three birds, congestion of the lungs and
pneumonia in two birds, degeneration of breast muscles in one
bird, white spots in the heart of one bird, air sac infection in
one bird, and joint infection in one bird.

When the authors of the report on the European study had
complete background histories on birds submitted for examination,
they found the following information in five cases. In one case,
10?14 day?old youngsters died after 1?2 days of prostration and
lack of appetite. It was found that only one of the two
youngsters in a pair was affected. The liver of these birds was
mottled and congested, along with congestion of the kidneys.
In another case, breeders housed in a densely?stocked loft
in which sanitation was poor, lost weight. New pigeons had been
introduced to the loft on a regular basis. Liver and spleen of
two birds examined were severely congested. Inflammation of the
liver and kidneys was also found.

In a third case, one bird from each of three pairs of
breeders died suddenly in a period of one week, right after their
eggs hatched. Their youngsters and other breeders remained
healthy. These birds had been examined for Streptococcus bovis a
few months earlier, and were found to be entirely negative.
However, several new pigeons had been introduced to the loft in
the meantime. These breeders had a septicaemia, and colonies of
organisms were found distributed to many tissues.

In a fourth case, one bird had chronic arthritis of the hock
joint and abscess?like changes in the kidneys after it had
survived an outbreak of paratyphoid, and did not respond to
treatment with Baytril. (Note this point about Baytril and
Streptococcus bovis! See later information.) A pure culture of
Streptococcus bovis was recovered from the liver and hock joint
of this bird.

In the final case, a bird had died after one day's illness.
Post mortem examination revealed a one?inch diameter pale, hard
area in the left breast muscle. Many bacteria typical of
Streptococcus bovis were found in this area.

Distilled to its essentials, Streptococcus bovis manifests
its presence in pigeons in a number of ways, including invasion
of the bloodstream and massive multiplication and distribution to
a number of tissues and organs (liver, kidney, spleen, muscle,
lung, heart, air sacs, joints), as well as infection of the
intestines and production of diarrhea.

Experimentally, the same researchers inoculated cultures of
this organism into pigeons, firstly by intravenous injection in
one group, and in a second group, by mouth. All pigeons injected
intravenously became very ill and developed excess urination,
beginning from the first week of this study. One young bird
became lame by the 12th day, and at post mortem examination, this
bird plus three others were found to be in poor body condition,
and had enlargement of the liver and spleen. The affected joint
contained yellow, creamy material.

Five other birds also injected intravenously with
Streptococcus bovis were observed for a total of 50 days after
inoculation. Three of these birds passed a great deal of urine
at intervals, and all of these birds had marked weight loss of
10?19%. Streptococcus bovis was not cultured from any tissue
when this group of birds was examined at post mortem on day 50.
In the group of six birds inoculated with Streptococcus
bovis by mouth, two birds began to pass the organism in droppings
by the third day, and another bird, by the fourth day. The other
birds in the group did not shed this organism in their droppings.
Two of the three pigeons shedding the organism in droppings were
also found to have it in the throat. All birds in this group
became negative on culture after one month, and none of them
developed any sign of illness during the experiment.
The results of these experiments showed that the disease
that occurred in inoculated birds varied considerably in its
expression. As well, the course of the disease varied from very
acute to chronic. The results also indicated that the disease is
very difficult to diagnose without a post mortem examination and
a bacterial culture of several tissues. They also showed that
the signs and changes in this streptococcal disease mimic those
of paratyphoid.

Another European study published in 1993 presented
information on antibiotic treatment of infections caused by
Streptococcus bovis in pigeons. It had been shown in earlier
experiments that this organism was recovered from the intestines
of 40% of healthy pigeons of all ages, and that pigeons that
carry the organism in the intestines usually do not develop this
disease. It was the opinion of these investigators that some
unknown factor(s) might predispose pigeons to development of
infections in the bloodstream, and as a result, disease. Signs
of the disease include sudden death in pigeons of all ages,
inability to fly, lameness, emaciation, excess urination, and
green, slimy droppings.

In the usual course of events in determining the best
product to use in treatment, human and veterinary diagnostic
laboratories run specific tests on bacteria that are cultured
from tissues of diseased humans, birds and animals, to provide
guidance in the choice of antibiotic or other product to use in
treatment. In this study, cultures of Streptococcus bovis were
inoculated intravenously into several groups of pigeons.
However, 48 hours before the intravenous injections, each group
of pigeons was given a different, specific antibiotic in the
drinking water, and these treatments continued through until 72
hours after the inoculation.

The results indicated that ampicillin and doxycycline
prevented illness in 80% of birds tested, erythromycin in 70% of
birds tested, enrofloxacin (Baytril) in 30% of birds tested, and
trimethoprim in 10% of birds tested. Obviously, the two poorest
drugs in these tests were Baytril and trimethoprim, so they would
not likely be the first choices for treatment of this disease,
although are very useful in other situations. The results of
these experiments involving live birds treated with antibiotics
correlated very well with the usual type of antibiotic
sensitivity testing done routinely by many veterinary diagnostic
laboratories. In such laboratory tests, live birds and animals
are not used, but even so, agreement between the two types of
tests was very good.

Overall, the authors of this study concluded that, under
field conditions, ampicillin is likely the antibiotic of choice
in the treatment of Streptococcus bovis, since in general, most
species of Streptococcus tend to be highly sensitive to
penicillin and amoxicillin (chemical relatives of ampicillin).
However, Streptococcus bovis seems to have acquired high
resistance to antibiotics such as the tetracyclines (eg.
Aureomycin and Terramycin, for example). Most strains of this
organism were highly sensitive to erythromycin, but because
strains of lactobacilli living in the crop of pigeons are able to
inactivate erythromycin and spiramycin, the use of erythromycin
in pigeons may be limited.

A further key finding in the use of antibiotics was that the
much?touted Baytril was among the poorest products in dealing
with this infection. Given the widespread use ?? and, I suspect,
overuse and misuse ?? of Baytril, it is reasonable that fanciers
would reach for the Baytril when a streptococcal infection occurs
in their birds, but information from Europe indicates that it is
not the drug of choice in treating this streptococcal infection.

Because Streptococcus bovis is an organism that can be part
of the normal bacterial population of the intestines of normal
healthy pigeons, the factors that allow it to invade the
bloodstream of pigeons are presently unknown. Some clues suggest
that such invasion may be related to poor sanitation in pigeon
lofts in which the disease occurs. Poor sanitation may allow for
a massive buildup of potentially dangerous bacteria, viruses,
etc., and exposure of pigeons to such huge numbers of organisms
can overwhelm their immune systems, and allow disease to occur.
Housing pigeons on wire floors may be a partial answer, because,
according to this study, the lowest prevalence of this disease
occurred in lofts with wire floors. (Given the various
manifestations of this streptococcal infection, it is also
tempting to wonder about the role of other agents, such as
circovirus for example, which is known to damage the immune
system of pigeons so severely that they become highly susceptible
to many other infections.

Whether the European investigators
looked for this or other intercurrent viral agents can't be
determined from a perusal of their published work.)
Although certain antibiotics seem to offer good control of
the disease, at least based on current studies, treatment in the
field situations may be somewhat more difficult. This is because
these infections often have a good start before antibiotics are
used in the first place, and poor sanitation in these lofts may
interfere with treatment. During outbreaks in Europe, it was
found that excretion of Streptococcus bovis from the intestines
of pigeons resumed once antibiotic treatment stopped ?? which
means that these organisms continued to live in the environment,
ready to cause disease again at a future time.

It is possible that on a practical level, Streptococcus
bovis will prove to be a difficult bacterial organism to deal
with. It seems that improved or well?maintained sanitary
practices in the loft will go a long way toward prevention of
infections, but even so, there is no guarantee that disease
caused by this organism will not occur. Only time and
investigation will identify a number of the factors that play a
role, not only in the development of this disease, but in methods
of control and prevention. Whether veterinary diagnostic
laboratories in North America are reporting these infections in
pigeons is unknown at this writing.

If sudden death or unexplained illness occurs in a loft when
sanitation is not the best, or if new birds have been introduced
prior to the onset of illnesses or death, it is important,
regardless of the cause, to have birds examined by a veterinary
practitioner, especially one who is familiar with pigeons or
exotic birds. Submission of representative birds by your
veterinarian to a diagnostic laboratory can help immensely in
detecting infectious or other diseases, and defining the precise
cause, as well as providing information on the correct treatment.
This is as true for all infectious diseases as it is for the
disease caused by Streptococcus bovis.

As fanciers, we need to be aware of this and other diseases
of pigeons, particularly since so many such diseases can be
imported along with pigeons from all areas of the world. Given
the brisk world?wide trade in pigeons today, especially from the
European hotbeds of racing, it seems only inevitable that this
and other important diseases will land on our doorstep ?? and of
course, quite a number have arrived by these means already.

In summary, it is important to note that infections caused
by Streptococcus bovis in pigeons can mimic those caused by
paratyphoid organisms, possibly E. coli, and in some instances,
could be confused with adenoviral infections. The key is to have
affected birds examined by post mortem, and to have various
organs cultured to determine the identity of the bacterial agent
causing the problem.

Only in this way can a cause be determined
when losses such as those described earlier occur in a racing
loft.

One last reminder: Baytril is NOT the drug of choice in
this disease!

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