Old World Aviaries

Antimicrobials commonly used in avian medicine—Part I. Overview

by Darrel K. Styles, DVM
Schubot Exotic Bird Health Center
Texas A&M University

(Note: This article was written in 1996. Therefore, newer drugs may be available. Ed.)

Antimicrobials are drugs used to combat infectious diseases. The four classes of antimicrobials are: antibiotics (antibacterials); antivirals; antifungals; and antiprotozoals. Each class is designed to treat different infectious disease types, although some of the drugs within a class may have some crossover activity.

In this series of articles, we will discuss the merits and problems of each class of antimicrobials and their respective subclasses. The list of drugs will be by no means comprehensive. The intent is to give you a cursory knowledge of the medications being used on your birds and the basis for rational drug therapy.

This overview article is the first in the series. It is designed to acquaint you with some of the medical jargon and drug names. We will examine the specifics of each class in future articles. We will exclude the anthelminthic or antiparasitic (worms, lice, mites, and such) types of drugs for now.

Each drug has at least three names, the chemical name, the generic name, and the trade name(s). The chemical name is the scientific or chemical description of the drug. The chemical name is not commonly used outside of industry or research. For example, amoxicillin is a drug with which we are all familiar. Amoxicillin’s chemical name is:

[2S-[2(alpha),5(alpha),6(beta)(S*)]]-6-[[Amino(4-hydroxyphenyl) acetyl] amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid; (-)-6-[2-amino-2-(p-hydroxyphenyl) acetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid

You can quote me on that.

So you can see that a simpler name is needed and that is the generic name, amoxicillin. The generic name is the “real” or technical name for the drug used by industry and the medical profession.

Drugs usually have only one generic name. However, a drug may have multiple trade names. When a patent expires, many companies make their own version of a drug, which will have identical chemical and generic names, but a different trade name. Continuing our amoxicillin example, this drug has a myriad of trade names, such as Amoxi-Drops. The generic name will be given in each example followed by a common trade name parenthetically.

Let’s now begin our investigation of the antimicrobials.

Antibiotics are drugs that classically are used in the treatment of bacterial diseases. These drugs combat bacteria such as Salmonella, E. coli, Klebsiella, and Chlamydia. There are multiple subclasses within the class of antibiotics. The subclasses of antibiotics commonly used in avian medicine including some pertinent drugs of each subclass are:

These are some of the most commonly employed antibacterials in avian medicine, although the list is by no means comprehensive. Each subclass is used for targeting different bacterial types. In later articles, we will discuss in detail how to select a drug depending on infection type, patient status, and other factors that dictate rational drug therapy.

Antivirals are used to treat viral infections. Medicine is woefully lacking in this drug group, and avian medicine has only one drug that is somewhat effective in treating herpesviruses, such as Pacheco’s herpesvirus infections:

This drug is helpful in preventing the spread of Pacheco’s disease and assists in the treatment of infected birds.

Antifungals are used to combat fungal diseases. Only a few in this class are commonly used, and much like the antivirals, more antifungal drugs are needed. The two types of fungi commonly encountered as pathogens are yeast-types, such as Candida, and hyphal-types, such as Aspergillus and Rhizopus.

The type of fungus present and its location in the patient dictates which drug we will employ, since some of the drugs are systemic and others are not.

Antiprotozoals are another category in which much work is needed to find new and improved drugs. This class is used to treat mainly Giardia, Trichomonas, and Coccidia infections.

This class is highly specialized and a definitive diagnosis must exist before selection can be made.

So, you see that just understanding the basics of rational drug therapy is quite an undertaking. The next articles in this series will examine each class separately and look at drugs from each in detail, so stay tuned.

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