Drugs

• To prevent illness
• To treat illness

Although a producer may depend on management for coccidiosis control, a drug such as amprolium is useful for rescue treatment in the case of an outbreak. There is no need to destroy infected birds; they can be treated. In large houses, it is necessary to routinely use drugs or vaccines because of the high density of birds.

• Sulfa drugs: An exciting discovery in the 1930s was that sulfa drugs would prevent coccidiosis – the first drugs shown to do so. Sulfa drugs also have some antibacterial action. However, a relatively large amount of sulfa was needed (10-20 percent of the diet) and could be tolerated by the bird for only a short time, since it caused rickets. (Reid, 1990) Sulfa drugs had to be used intermittently (e.g., three days on and three days off). Nowadays, comparatively small amounts of sulfamonaides, such as sulfaquinoxaline, are used. They work only against Eimeria acervulina and Eimeria maxima, not against Eimeria tenella. Sulfamonaides are used to treat coccidiosis.
• Amprolium: Amprolium is an anticoccidial drug. It has also been used for many years and needs no withdrawal time to guard against residue in the meat. It is given in the drinking water and interferes with metabolism of the vitamin thiamin (vitamin B1) in coccidia. Amprolium treats both intestinal and cecal coccidia.
• Quinolones: Quinolones are “coccidiostats” that arrest the coccidia in an early stage of development. An example is decoquinate (Deccox®). The drugs are used for prevention.
• Ionophores: Ionophores are anticoccidials commonly used in the large-scale industry. They alter the function of the cell membrane and rupture the parasite. Ionophores also have antibacterial action and help prevent secondary gut diseases. Ionophores are not synthetic drugs; they are produced by fermentation and include monensin (Coban®) and salinomycin (Salinomax®). However, some ionophores are now completely ineffective against coccidia because of resistance the coccidia have developed. They are used for prevention.
• Other drugs: There are many other anticoccidial drugs in various chemical classes with various modes of action. Examples are Cycarb® (nicarbizine) and Cycostat® (Robenidine Hydrochloride).

Using Drugs

You need a veterinarian’s prescription to use drugs for poultry (but not to use vaccines). Feed mills need a license to put drugs in feed.

In the large-scale industry, drugs are used for prevention rather than treatment. If you treat the bird after an outbreak, the damage is already done. Many preventative drugs are effective only in the first part of the parasite life cycle, and therefore must be used early if they are to be used at all.

Drawbacks of using preventative drugs are their expense and he resistance that coccidia have developed. The drugs are not as effective now as when they were first introduced. Large companies use a drug rotation or shuttle program to reduce resistance.

There are not many new anticoccidial drugs because of the extensive process for FDA approval. It costs millions of dollars to develop a new anticoccial drug and get it approved for use.

In the large-scale industry, most anticoccidial drugs are withdrawn a week before slaughter of broilers to save money or to prevent residue in the meat. Drugs are withdrawn before layers begin laying eggs to prevent residues in the eggs.

Small producers often give pullets medicated feed while in the brooder, and then remove medication when they are older and placed in pasture-based systems.

Unfortunately, drugs used for prevention usually interfere with development of immunity to coccidia. On the other hand, using drugs for treatment only does allow immunity to develop. If signs of the disease appear, use drugs that are appropriate for coccidia’s late life cycle – only sulfonamides and amprolium. (Reid, 1990) When birds are getting sick, they lose their appetite. Therefore, soluble medication should be provided in the drinking water.