Old World Aviaries

Too much of a good thing

by Darrel K. Styles, DVM
Hill Country Aviaries, L.L.C.

I am frequently confronted with the problem of over medication of either a flock or an individual bird. Often, the concerned aviculturist will place his or her birds on a broad-spectrum antibiotic and treat the medication as if it was a “spring tonic.” I would like to emphatically stress that this procedure frequently does more harm than good and is usually unwarranted.

Nature is truly a balance—whether this concerns processes or relationships between organisms. We live in harmony with our native bacteria, and all God’s creatures have their own indigenous flora (meaning bacteria). Therefore, not all bacteria are harmful, and many are beneficial for several reasons. In birds, not only do native bacteria help digestion, they also compete with pathogenic bacteria and prevent colonization by these pathogenic bacteria unless the bird is massively challenged or the bird’s immune system is not functioning properly as in stress. If we artificially upset the balance between the bird and its own bacteria, we can induce a pathogenic state rather than prevent it.

The good or indigenous bacteria in avian species includes Lactobacillus, fecal Streptococcus, fecal Staphylococcus, Corynebacterium, and even E. coli. All these bacteria are Gram positive except E.coli. And as we all know, E. coli can serve as either a pathogenic or bystander bacterium. If we treat birds with an antibiotic just because we think they need it or the birds are ADR (Ain’t Doin’ Rite), then we may at best do nothing to correct the problem, or more likely, at worst induce or mask a pathogenic state. For this reason, it is always essential to culture, and then treat presumptively until your culture is confirmed. This should always be done by or under the direction of an avian veterinarian. If an inappropriate antibiotic is chosen, we may kill the good bacteria that were competing with the pathogenic bacteria and allow the disease-causing bacteria to grow unchecked.

The other major problem this type of therapy causes is the development of resistance. A good number of misconceptions exist about bacterial antibiotic resistance. The bacteria do not mutate in response to the treatment, but we select for bacteria that already have the ability to survive the antibiotic. In other words, there is sufficient genetic diversity within a bacterial population such that there exists some finite number of organisms that are resistant to any given antibiotic. So, by treating pell mell, we are destroying the good bacteria and the sensitive bad bacteria, but the antibiotic-resistant bacteria go on to thrive and reproduce.

To give you an example, when I was starting out in avian medicine in 1985, we used tons of penicillin and gentamycin at quarantine stations. After about 3–4 years, almost all of the avian strains of E. coli were resistant to penicillin-type drugs, and many E. coli strains were resistant to the supposedly undefeatable gentamycin. So, even veterinarians have helped to contribute to the number of antibiotic-resistant strains of bacteria.

There is an alarming trend that I have observed among aviculturists, and that is that we are much too quick to reach for the bottle of Baytril for just any problem. People, believe me, if this type of behavior continues we will have nothing left in our drug armamentarium with which to battle the bugs. When the quinolones were introduced—the quinolones are the class of drugs to which Baytril and Cipro belong—the drug companies assured the medical profession that the drugs were resistance proof. They were wrong. Even in human medicine, an alarming number of quinolone-resistant bacteria exist, and drug researchers are losing the battle against the bacteria. So, drugs should be used wisely, sparingly, and only when necessary.

There are instances when broad-spectrum treatment is warranted, such as in the treatment of Chlamydia (psittacosis). But, we have a legitimate reason to do so and understand what consequences may arise from such treatment. (By the way, many Gram-negative bacteria such as E. coli are resistant to the common tetracyclines used to treat this illness.)

My recommendation is this: treat only under the supervision of an avian veterinarian after the appropriate culture has been obtained. Your vet can help you to select an appropriate treatment regimen until confirmation on the culture and sensitivity results are in. The most important tenet I learned in vet school was the ancient medical axiom, “at the least, do no harm.” I am a firm believer in this truism.

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