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Sick Chicken? Here Are the 15 Most Common Chicken Diseases (Plus, Prevention & Cure)

Are you dealing with fatal poultry diseases or a simple mite infection?

We’ve gathered information on some of the most common chicken diseases so you can help diagnose your backyard chickens and figure out what you can do to keep those guys alive, healthy, and layin’!

Common Chicken Diseases That You Should Know

Avian InfluenzaDiarrhea, breathing issues, and no appetiteYes
BumblefootPink/callused legsNo
CoccidiosisBloody diarrheaNo
Fowl CholeraFever, reduced appetite, heavy breathingYes
Fowl PoxSores/respiratory issuesNo
Infectious BronchitisLabored breathing/watery dischargeNo
Infectious CoryzaFacial swelling with discharge Yes
Lymphoid LeukosisComb regression/large abdomenYes
Marek’s DiseaseParalysis, drooping wings, enlarged feather folliclesYes
Mushy ChickExternal navel infectionYes
Newcastle DiseaseRunny nostrils, paralysis, twisting of the neckYes
SalmonellosisLethargy, puffy eyes, ruffled feathersYes
Scaly LegRoughness and unevenness of the legsNo
ThrushOozy white secretion around the neckNo

The goal here is to highlight some of the most common chicken diseases. However, keep in mind that there are countless other diseases out there.

1. Avian Influenza

More commonly known as “bird flu,” Avian Influenza has become alarming to humans because of the infectious rate at which it can spread and kill off a flock – not to mention the possible transfer to humans as well.


Anything from an improperly disposed-of carcass to infected rodents, equipment, and even people can all spread the disease.


Milder forms of Avian Flu can lead to tiredness, diarrhea, breathing issues, a decline in eating, and decreased egg production. For severe cases, dark red and white spots can develop on the legs and combs.

Also, blood-tinged discharge from the nostrils is common and facial swelling and blue combs and/or wattles.


There is no effective treatment available at this time.

You can read more about the Avian Flu here.

2. Botulism

Next on the list is another worldwide sickness familiar to our collective ear: Botulism.


Botulism bacteria can come from pond scum, maggots, plant waste, and the classic – rotting meat.


Tremors and paralysis are common. You may find birds unable to stand or lift its head (1).

Sometimes birds may just be found dead, with no evidence of struggling. There is no diarrhea or nasal discharge and no signs of injury.

Eventually, the paralysis can extend to breathing, at which point you can lose the animal.


The poultry vet will administer antitoxins.  

3. Bumblefoot

Bumblefoot is a chicken’s version of a staph infection in their leg (hence the “foot” part…)


This bacteria, which comes from the soil, can appear especially after a heavy rain disrupts any stagnant water in the chicken’s environment.


A bird with Bumblefoot has some pretty gnarly-looking legs – pink, callused and covered in sores. If left untreated, the whole foot turns dark blue or even black.


Antibiotics are effective. Dietary change and even surgery are options as well.

Here is a good source for more information on Bumblefoot in chickens.

4. Coccidiosis

Coccidiosis is a chicken disease that invades the bird’s intestinal tract.


The parasite is ingested from the chicken’s environment in its egg form and then reproduces, at which point more eggs leave through the chicken’s feces.


Look out for diarrhea with blood and mucus and losing weight. Ruffled feathers and listless activity are also symptoms.


Get an anticoccidial agent like amprolium or toltrazuril. A gentler alternative is using an essential oil like thyme, tea tree, or clove.

5. Fowl Cholera

First diagnosed over a century ago, fowl cholera is one of the more serious diseases in winter when chickens are closer together.


It can spread from things like rats, possums, and other rodents and wildfowl that stop in for a visit.


When the outbreak is serious, the first symptom you might run into is death.

However, monitor your backyard flock for symptoms such as fever, reduced appetite, heavy breathing, mucus from the mouth, diarrhea, and ruffled feathers.

Weight loss, losing the ability to walk, swollen joints, and abscessed wattles are warning signs too.


Antibiotics are available, however, if the bird recovers, it’s still a carrier. Preventative treatments like vaccination can prevent the further spread of the disease.

Really, though, keeping those pesky rodents out is the best long-term preventative you can find.

You can get some more info on this illness here (the first one under Nonrespiratory Bacterial Diseases).

6. Fowl Pox

Note: this is not the same illness in humans.


Fowl Pox spreads from direct contact between chickens and can spread through scabs that have fallen off, skin that has been scraped, breathing, and even through a bird’s eyes.


There are two kinds of Fowl Pox – dry form and wet form.

Symptoms of a dry form include warty, raised spots on featherless areas while wet form comes with actual pox in the mouth and throat.

You can learn more about Fowl Pox here.


There is no known treatment available, but it spreads slowly, you should conduct preventative measures.

7. Infectious Bronchitis

This incredibly contagious viral disease plagues chickens in particular, rather than birds in general.


The virus can spread through many transmissions, including feed bags, dead birds, infected coops, and those good-for-nothing rodents. But most commonly, it can spread via the air.


Chickens with Infectious Bronchitis will eat and drink less and develop a watery discharge from their eyes and nostrils. They will begin to have heavy and labored breathing and lay fewer eggs.


There is little to do once your chickens already have the virus besides taking good, rehabilitative care of them.

Regular cleaning of your coop and vaccination can help manage and prevent this infectious chicken disease from spreading.

Vaccines are available to prevent contracting the disease, but it must be given early on in life (within the first 15 weeks) as eventually, it will stop the hen from laying eggs. If you want to learn the other reasons why chickens stop laying eggs, read here.

8. Infectious Coryza

Infectious Coryza is a bacteria-driven respiratory infection.


This disease transmits merely when two birds make contact, although airborne transmission is another possibility.

Chickens who have recovered can carry the disease as well, so be careful when introducing a new chicken into your flock.


Coryza usually involves facial swelling accompanied by a thick, sticky discharge thick, sticky discharge. An infected bird also smells bad.


Antibiotics and antibacterials are both options.

Here’s a bit more information on Infectious Coryza.

9. Lymphoid Leukosis

It is a viral, tumor-forming disease that targets the organs of adult birds in particular.


It is very hard to know when this is happening, as so much of the damage takes place inside before exterior symptoms reveal what’s going on.


Weakness can gradually increase along with comb regression, an enlarged abdomen, and a loss of appetite along with emaciation. If greenish diarrhea develops, it is a sign that the bird is terminal.


There is currently no known treatment.

10. Marek’s Disease

This tumor-driven virus affects the nervous system.


It transmits through the air via chicken dander/dust and can lie dormant in a seemingly healthy host for as long as a year. It does not spread directly from parent to egg


Lameness, paralysis, drooping wings, weight loss, enlarged feather follicles, paleness, loss of appetite, blindness, and reddened, bloody-looking shanks (lower legs) can all be symptoms that something is going on.


You can only vaccinate against Marek’s Disease before tumors develop. But even vaccinated chickens can still be carriers.

If you’re interested in learning some more information on this one, you can find it here.

11. Mushy Chick

Officially known as Omphalitis, “Mushy Chick” infects new chicks shortly after hatching.


The navel can become infected if it comes in contact with a dirty environment, such as soiled eggs, unclean hatching boxes, etc.


External navel infection, including abnormally large, unused yolk sacs, and a very bad smelling peritonitis (a swelling infection of the abdomen).


Some sources claim that antibiotics can give the chick a chance at recovery – although this is a long shot.

Prevention can be easily attained by keeping your hatchery clean – one of the many rules of raising healthy chicks and creating a good environment for them.

More information on Mushy Chick disease can be found here.

12. Newcastle Disease

This viral infection attacks the nervous system and can vary in its intensity.


This disease can spread short distances through the air, but it is more likely to be transmitted through contaminated “outsiders.”


Wheezing, running nostrils, heavy breathing, swelling in the face, paralysis, trembling, and twisting of the neck, like this:


There isn’t treatment at this point.

Here is a good source for further information if needed!

13. Salmonellosis

This bacterial disease can show up in various forms, including Arizonosis, Pullorum disease, fowl typhoid, and paratyphoid (see the breakdown here).

It is also more dangerous during cold seasons when chickens live in close quarters due to the weather.


This one can spread vertically (from parent to child) and horizontally (between adult chickens).

The latter can come in many forms, including an infected coop, food, boots and hands, rodents, bugs, and the addition of new birds to the flock.


Watch out for lethargy, puffy eyes, ruffled feathers, dehydration, lowered egg production, white, chalky diarrhea, and pasty vents.


Probiotics in a supplement form or even yogurt can help fight off the infection.

You may want to check out our articles on How Cold Is Too Cold For Chickens, and How To Keep Your Chicken Water From Freezing for some top tips and recommendations! 

14. Scaly Leg

This one is a basic infection with a simple (and gross) cause: mites.


Mites burrow down into the chicken’s skin, causing particularly bad damage to their legs and feet.


Roughness and unevenness, and straight-up deterioration of the skin’s legs and feet are obvious signs of Scaly Leg.


Use topical ointments like vegetable oil, olive oil, coconut oil, and even petroleum jelly. You can also use Diatomaceous earth and Ivermectin, but please consult a vet before you do.

If you think you’re dealing with Scaly Leg and need more information, you can find it here.

15. Thrush

Thrush or Candidiasis is a fungal disease much like the infection seen in humans.


Thrush transmits through a moldy feed, water, or other contaminated surfaces.


An oozy white secretion between the neck and the body is common, but overeating, lethargy, ruffled feathers, and a crusty vent area can occur.


Your vet will prescribe an antifungal medication.

Here is a great follow up source for dealing with fungal infections like Thrush (second down on the list!)

Wrapping Things Up

Having the right information on the types of poultry diseases can help you diagnose what your flock is suffering from. Also, remember to call the vet if things are looking serious!

Now that you’ve got the rundown on what your chicken is dealing with, you can go help out your flock!

But before you do, please share this post!


Chicken diseases that you can prevent include the New Castle Disease, infectious bronchitis, fowl pox, and more. If your chickens are not vaccinated yet, you can consult your veterinarian for a suitable vaccination program.

You should immediately take your chickens to a vet if you noticed any signs of lethargy, ruffled feathers, and diarrhea. Waiting too long can cause the spread of the illness to the rest of your flock, especially if it’s an airborne and highly contagious disease.

Yes, a vaccinated chicken with Marek’s disease can pass the illness to unvaccinated birds. Fortunately, this deadly chicken disease is preventable by having your birds, young and adult, vaccinated.

  1. Botulism in chickens, ducks and other poultry. Retrieved from:
  2. Preventing omphalitis to reduce first week mortality. Retrieved from:

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