If you plan to raise chickens, you must be ready to encounter parasites. Even a city chicken coop can be invaded. Internal parasites — in particular worms and coccidiosis — are especially problematic, so it’s important to understand how chickens are affected by parasites and how to treat parasites.

Treating worms in chickens

Chickens are most often affected by roundworms, tapeworms, and gapeworms. Chickens that have worms may look unhealthy and thin. They may gain weight slowly even though they eat more feed than chickens without worms, and they may lay fewer eggs. Many species of worms, however, can live in chickens and not cause any problems. If you notice worms or your chickens don’t seem to be as healthy as they could be, it may be time to check for worms and treat if necessary.

Make a habit of checking out chicken droppings because some worms are visible in droppings. Even if the worms aren’t visible, a veterinarian can examine the droppings in a lab. She looks for worm eggs or actual worms. Sometimes these lab tests aren’t successful, because worm eggs weren’t being produced when the sample was collected.

Generally, treatment for chicken worms consists of worming the entire flock. Some people prefer to worm chickens at least twice a year as a precaution, even if they don’t see worms or symptoms. It doesn’t hurt to worm as a preventive measure if you follow the directions for the worm medication. However, we don’t believe that home flocks need to be wormed as a precaution if they appear healthy and you don’t see worms in the droppings.

If you worm meat chicks, you need to follow label directions about how long to keep the birds before they can be butchered for eating; you don’t want pesticide residues to remain in the meat.

Treating cocciodosis in chickens

Coccidia are most often a problem in young, growing birds, but occasionally Coccidia can cause problems with older birds, especially if they get bacterial diseases such as ulcerative colitis. Birds under 3 weeks seldom show symptoms. Slightly older chicks from 3 weeks to 30 weeks may have bloody diarrhea, anemia, pale skin color, listlessness, poor appetite, or dehydration. Young birds with heavy infestations of Coccidia often die.

Chickens get Coccidia by ingesting oocysts, which are immature Coccidia that are passed in fecal matter. The oocysts contaminate feed, litter, and soil and can last for a year in the environment. They can be spread by shoes, clothing, equipment, wild birds, pests like rats, and infected chickens.

Good treatments for coccidiosis are available. Feeding baby chicks a starter feed medicated with coccidiostats (which kill Coccidia) is advisable for the first month. You also can put certain medications into the chickens’ drinking water. Amprolium and Decoquinate are commonly available coccidiostats. If older birds seem to be infected, you can treat them with these medications as well.