4 Common Chicken Diseases : Causes, Symptoms, Treatment, Prevention

As a chicken enthusiast, small backyard farmer or commercial poultry franchise owner, one of your top priorities is keeping your birds happy and healthy.

You may very well be versed in some of the common diseases and conditions that affect chickens and be able to treat those yourself. But what do you do when a chicken gets a disease you don’t recognize or don’t know how to treat?

Chicken Diseases

There are four types of diseases and conditions that are most likely to strike your birds: diseases related to metabolism and nutrition, infections, parasites and behavioral concerns. With so many different types of chicken diseases and conditions, there is bound to be a time when you are not sure what to do.

Here are some of the more common chicken diseases, how to recognize them and tips for treatment.



Coccidiosis is one of the most common parasitic chicken diseases. According to livestock feed company, Bentoli, Coccidiosis causes damage to the walls of a chicken’s gut through “the destruction of intestinal epithelial cells.” Coccidiosis is one of the most common chicken diseases because all birds carry some strain of the disease, although not all birds will contract it.

One of the most serious dangers of this condition is that it can also exacerbate other conditions, or even lead to worse chicken diseases. Chicks are also more prone to contracting the disease than adult birds since they have not had time to build a strong immune system.

Contraction Of Coccidiosis

The disease is initially contracted through the consumption of a parasitical single-cell organism or oocyst, that is spread via spores. “Coccidiosis starts with an oocyst, or microscopic egg, that is passed through a chicken’s droppings.” The egg may lie dormant for some time before it sporulates.

A sporulated oocyst is often consumed through contaminated or water. The parasite may also be picked up when a chicken scratches the ground to find worms and insects. When consumed, the oocyst will make a home in the chicken’s gut by attaching itself to the intestinal lining.

This allows the parasite to begin a lifecycle and continue to multiply. As the parasite takes over, the intestine’s healthy functions are compromised, causing a number of both visible and non-visible symptoms.

Symptoms of Coccidiosis

The most common symptom of the disease is blood or mucus in chicken droppings. However, you should be aware that there are both other chicken diseases and other perfectly normal reasons, why a chicken’s droppings might appear red or reddish-brown.

chicken coccidiosis

Other very common noticeable symptoms of Coccidiosis include loss of appetite, diarrhea and weight loss. Weight loss will occur due to the bird no longer wanting to eat, diarrhea and because they are not able to absorb some necessary nutrients. If you notice that your chickens have unkempt or ruffled feathers, pale combs or skin or a general sense of fatigue or weakness, these may also be signs that Coccidiosis is present.

Treatment For Coccidiosis

Treatment for Coccidiosis can be a fairly simple matter, especially if you catch the condition early enough.

Coccidiosis is treated with the antiprotozoal Amprolium, commonly sold under the brand names Amprol and Corid. This medicine for chicken diseases can be administered through food or water. However, since Coccidiosis does cause a lack of appetite, you may need to manually administer the medicine to your chickens orally.

The good news is that with quick treatment with Amprolium, and by treating your entire flock, you can usually cure an outbreak of Coccidiosis fairly quickly. It should only take around a week to fully eradicate the condition.

If you are wanting something more specific, you can read our article: Coccidiosis in Chickens: How to Treat and Prevent.

Fowl Cholera

Fowl Cholera

Fowl cholera is one of the more highly infectious chicken diseases that can be a risk to your birds. According to the MSU extension, this condition, also transferred through a parasite found in chicken droppings, is so easily spread because, unlike some chicken diseases, it does affect many other species of birds.

All of the following can carry and spread this disease from species to species: chickens, turkeys, pheasants, pigeons, waterfowl and sparrows.

This disease causes infection of the raspatory system, joints, small intestine, liver and spleen. It may also cause pneumonia type symptoms resulting from infections in the ears and lungs.

Contraction Of Fowl Cholera

Fowl Cholera is contracted through the intake of a bacterial organism called Pasteurella multocida. These bacterial cells are nonmotile, or, in other words, they do not spread via spores and are not able to move on their own.

The bacteria generally enter the body through the mouth or via the upper respiratory tracts. Pasteurella multocida parasites are probably most commonly consumed through contaminated food and water sources.

The disease can also be spread through the remains of other dead birds, including the nonpoultry species listed above. The MSU Extension reports that studies suggest other animals, including pets and wild animals, may also be able to spread the disease to chickens. Further, the bacteria that cause Fowl Cholera can be transmitted via transfer from shoes, equipment or tools.

Because Fowl Cholera is one of the chicken diseases more likely to be contracted by older birds, it very rarely affects chicks. It is also more likely to be contracted by roosters than hens.

Symptoms of Fowl Cholera

Some birds may not be visibly ill before they die. But many chickens who suffer from this illness will show signs like disinterest in food and water, diarrhea, swollen wattles and combs, swollen joints, difficulty walking, lethargy and stupor.

Some birds with Fowl Cholera may produce discharge from the nose and eyes. An unkempt appearance, such as ruffled and dirty feathers, may also be a sign that Fowl Cholera is present. Some birds may also drop dead very suddenly.

Treatment For Fowl Cholera

Prevention is the only real cure for some chicken diseases, including Fowl Cholera. The best prevention methods involve a detailed sanitation routine. Since the cause is bacterial, preventing damp patches and other moisture build-ups in coops and yards will help prevent the disease.

You can also disinfect the coop, nesting boxes, perches, food and water receptacles and toys regularly. Just be sure to use disinfectants that will not harm your birds. Keeping rodents and wild birds out of your chicken habitat will also help to prevent Fowl Cholera. Be sure that extra food is kept in a secure area and set mouse and rat traps where necessary.

You can also treat your chickens with bacterins whether they are ill or not. These can work to prevent the disease and to lengthen the life of infected chickens. However, you should be aware that to completely eradicate the infection, the only solution is depopulation of your flock, since neither bacterins nor antibiotics can fully cure the disease.

After depopulation, be sure to thoroughly disinfect all areas and leave them empty for several weeks before adding new birds.

Avian Influenza

Avian Influenza

Avian Influenza is a respiratory illness found in birds. According to the USDA’s Animal and Plant Health Inspection Service, Avian Influenza, or AI, “is caused by an influenza type A virus.” The APHIS outlines the two different strains of AI: Highly pathogenic avian influenza (HPAI) and Low pathogenicity avian influenza (LPAI.).

The highly pathogenic strains are the ones that poultry owners should be concerned about it. The APHIS states that these “strains are extremely infectious, often fatal to domestic poultry, and can spread rapidly from flock to flock.”

The Indiana State Poultry Association warns that this disease is so powerful that “One gram (approximately one-fourth of a sugar packet) of contaminated manure can contain enough virus to infect 1 million birds.”

Contraction Of Avian Influenza

AI is most commonly spread directly from bird to bird. This happens through secretions of the raspatory system and via manure. The disease can also be contracted and spread when chickens come into contact with wild birds and other fowl that carry the disease.

Another contraction method is from contaminated equipment, vehicles, clothing and shoes. Smuggling and illegal movement of some chicken breeds may also encourage the spreading of Avian Influenza.

Symptoms Of Avian Influenza

Some of the most common signs of AI include lethargy, trouble walking, lack of appetite, diarrhea, lower rates of egg-laying, soft eggshells or misshapen eggs, discharge from the nose, coughing and sneezing.

Chickens with AI may also have swollen heads, eyes, combs and wattles and legs. There may also be discoloration in the wattles, combs and legs. Birds with AI may sometimes experience sudden death for no obvious visible reason.

Treatment For Avian Influenza

Prevention of Avian Influenza is the best cure. To prevent AI, and other chicken diseases, biosecurity and rigid sanitation practices should be in place.

Sanitation Tips For AI:

  • Prevent contact with wild birds
  • Keep rodents away from your flock
  • Wash hands before caring for chickens
  • Disinfect shoes in footbaths
  • Don’t visit other farms or homes with birds
  • Temporarily isolate new birds
  • Restrict visitors to your farm

Treating AI is a little more tricky than with some chicken diseases. According to the Merck Veterinary Manual, “Antigenically matched and properly administered vaccines can prevent clinical signs and death and greatly reduce virus replication.”

However, as there are many different subtypes of the virus, it is important to use the appropriate vaccine for the strain in question.

The Merck Manual also states that in some cases, broad-spectrum antibiotics may “control secondary pathogens and increasing house temperatures may reduce morbidity and mortality.

Infectious Coryza

chicken illnesses

Merck Veterinary Manual defines Infectious coryza as “an acute respiratory disease of chickens characterized by nasal discharge, sneezing, and swelling of the face under the eyes.”

Infectious Coryza, also sometimes known as the chicken cold or chicken croup, is caused by a bacteria called Haemophilus paragallinarum. The Poultry Site also states that the condition is more commonly contracted in flocks that are held on multi-age farms and that never see complete depopulation.

Contraction Of Infectious Coryza

Infectious Coryza is contracted through the conjunctival tissues of the eyes or through the nose. It can be airborne, transferred by direct contact with an infected bird or consumed through contaminated water.

Chickens with preexisting raspatory conditions, such as viral or bacterial infections, may be more prone to the disease. Older roosters and hens are also more likely to contract Infectious Coryza, although it can be contracted at any age. Unsanitary farms and coops are a major factor in the spreading of the disease.

Symptoms Of Infectious Coryza

Infectious Coryza

Common signs of Infectious Coryza that you should watch for include: facial swelling and swelling of the wattles, ocular or nasal discharge, lethargy or inactivity, lack of appetite, labored breathing and slowed egg production.

Of course, some of these symptoms, such as the wattle swelling, can be present in many other chicken diseases. Treatment should always be carefully selected based on multiple symptoms.

Treatment For Infectious Coryza

Antibiotics, through water or feed, are crucial to treating birds that have already contracted Infectious Coryza. Erythromycin and oxytetracycline are two such drugs that have generally helped with this condition.

Newer drugs, such as fluoroquinolones and macrolides, seem to show promise, as do medicines like sulfonamides and sulfonamide-trimethoprim combos.

As with the aforementioned chicken diseases, an ounce of prevention is worth a pound of cure. Keep your farm sanitized and consider complete depopulation versus continuously rotating various ages of birds. For tips on cleaning the manure from your coops, check out Farm Alarm’s video tutorial.


In summation, Coccidiosis, Fowl Cholera, Avian Influenza and Infectious Coryza are very common diseases among poultry. Since there is a high likelihood of at least one of these chicken diseases afflicting your flock at some stage, it is wise to remember the symptoms so that you can treat your birds, or seek treatment for them, as soon as you notice a problem.

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