Common Chicken Illnesses: Prevention & Treatment

Bookmark this handy guide to common chicken illnesses for best-practice prevention measures and steps to take when poultry start to look unhealthy.

by Kristina Mercedes Urquhart
PHOTO: boumenjapet/Adobe Stock

Here are some of the most common and concerning chicken ailments, illnesses and diseases, as well as how to prevent and treat them. 


Far less fatal and far less serious than some of the other chicken illnesses, bumblefoot is an easily preventable yet unfortunately rather common ailment in young and mature chickens. Bumblefoot is a chronic infection on the footpad, often the result of an injury that became infected. It’s easily diagnosed by locating the abscess on the footpad.

Bumblefoot is very easily prevented, far more so than treating it once it has occurred. Reduce—or eliminate, if you can—any time that your birds spend on wire. Keep the coop and all enclosures clean with deep, dry bedding, and clean the litter regularly. Keep all roosts sanded down and at heights birds can reach.

In short, avoid situations where the feet might become injured.

Bumblefoot can be very difficult to treat. In some cases, a veterinarian can inject penicillin into the swollen area. Otherwise, the abscess needs to be removed manually, dressed properly and kept incredibly clean. For humans, impetigo is a mild health risk, so wear gloves when handling birds with bumblefoot.


Properly called prolapse, a blowout occurs when the lower part of the oviduct is turned inside out and ends up on the outside of the vent. It’s a reproductive complication that can occur in any pullet or hen. But it is more common in certain breeds and strains of those breeds.

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Applying hemorrhoid cream to the vent and isolating the hen until she improves can remedy minor prolapsed vents. If she’s not treated or left with the flock, the other birds will undoubtedly pick at the vent and worsen the situation. Don’t take chances with flock cannibalism.

Prevention is important but can’t always save a hen from developing a blowout. Some hens are just bred to lay early or lay exceptionally large eggs, making them more prone to prolapse.

Raise breeds that don’t lay gargantuan eggs or start too early. Feed birds a properly managed diet that matches their age and stage of life. Hens with too much fat in their diets can accumulate fat stores in their reproductive system, making reproductive disorders more likely.


Several protozoa known as coccidia cause a rapidly advancing, often fatal disease called coccidiosis in very young and developing birds. Nine strains affect poultry.

Coccidia exist everywhere outdoors and are carried and sometimes transmitted from wild birds or other chicken flocks. While it’s possible for adult chickens to contract coccidiosis, it’s most common in chicks 3 to 5 weeks old and in humid, warm and damp conditions.

Unfortunately, the mortality rate of coccidiosis is very high compared to some other chicken illnesses. It’s most easily diagnosed by blood in the stool, but at that stage of development, the disease is almost always fatal, and the bird will not live long. Chicks with coccidiosis will show signs of droopiness, crouching with feathers ruffled, little or no appetite, and slow or no growth in the early stages of the disease.

Good sanitation is a crucial preventative measure against coccidiosis. Keep chick brooders clean, dry and free of excess droppings. Expose chicks gradually to any existing adult flocks to build their systems’ tolerance to the protozoa that live naturally in their environment. This is important for birds born in a hatchery and shipped to new surroundings.

Prevention also includes administering a vaccine on the first day of life. However, there are some caveats.

Vaccines must be given only on the first day of life to be effective, and the inoculations cover only six of the nine strains. Treatment for coccidiosis includes a medication called amprolium. Surviving birds are rarely as strong as birds that never contract the disease.

chicken illnesses ailments
Dmytro/Adobe Stock


The signs of conjunctivitis are clear, but you must look closely at the bird to read them. An affected bird will avoid sunlight and attempt to rub its eyes with its wings. The eyes can appear cloudy, or they might water, later becoming crusty with discharge. Blindness follows in progressed cases.

Mortality varies among birds and flocks, considering the initial and overall health of the hens. It some cases, it resembles a respiratory disease.

Thankfully, conjunctivitis is not contagious. But it is environmental, meaning sanitation and healthy management practices are paramount to preventing it.

Dusty and dry conditions can exacerbate it, but it’s often caused by the buildup of ammonia fumes in flocks confined to coops or enclosures without adequate airflow and thus are rather damp. Prevention is to replace soiled and wet litter with dry and clean bedding, and allow the flock adequate outside time to pasture.


Just like us, chickens can go longer without food than they can without water. When a chicken does drink water, it takes only a bit at a time. You’ll notice it dip its beak in the water, lean its head back and drink it down. 

The chicken will do this several times at each visit to the water fount. Because of this, birds need to drink often. Without sufficient water, hens will reduce egg production—an egg is more than 70 percent water, after all—and chicks will fail to thrive.

Dehydration runs on a spectrum. It’s possible for a bird to be deprived of water and not be completely dehydrated. This still has lasting effects on the bird’s health. Laying hens deprived of water for a day or more can take weeks to recover. Going without sufficient water for three days or more can result in a permanent state of weakened egg-laying.

Water deprivation or dehydration can happen for many reasons. Even if their waterer is filled each day, other factors can prevent birds from accessing the water. First, can all of the birds, regardless of size, reach the waterer? Is there something in the water that alters the taste—such as feces or algae—and is it clean? Are birds lower in the pecking order able to reach the waterer or are alpha hens preventing them?

Most importantly, have a good waterer that is built to hold enough water for the size of your flock. Fill it as often as needed so that clean, fresh water is always available. Only you can judge how often that is, based on your climate, flock size, season and style/size of water font.

Birds of different ages need varying amounts of water. The older a bird is, the more water it typically needs. In summer, keep waterers out of direct sun. In winter, take precautionary measures to make sure waterers don’t freeze, preventing the birds from accessing it.

While hotter months tend to suggest the need for more water, proper hydration in the winter is critical to staying warm.

Lastly, invest in a good watering system. Good water founts are raised up at the height of the smallest chicken’s back. They are also designed to prevent roosting and, thus, the contamination of fresh water with droppings.

Read more: Make sure your chickens have plenty of wate at all times!

Egg Binding

Egg binding is a very serious reproductive issue that is most common in young birds, called point-of-lay pullets. This ailment occurs when an egg becomes lodged in a chamber of the cloaca. It might be that a young bird is laying exceptionally large eggs, a disease caused the reproductive organs to swell or the issue is a matter of genetics. However it occurs, it’s important to know that an egg-bound hen is in a fatal predicament unless the egg is removed.

How do you know a hen is egg bound? It’s true that chickens will manifest many of the same symptoms for a wide range of illnesses. You have to be a bit of a detective to figure out exactly what’s wrong. With egg binding, there’s a telltale sign, something I call the “penguin stance.” 

An egg-bound hen—in addition to not laying, rarely eating or drinking, crouching or walking oddly—will stand in a very unusual position. With her tail tucked downward and her feathers fluffed out just a bit, the egg-bound hen resembles a penguin. She might not move or might move very slowly.

There are several ways to remedy egg binding. Because the egg is blocking the vent, this is not an ailment where you can wait for very long. It’s a serious condition that will kill the bird if untreated. If it’s within your means and your philosophy of chicken keeping, you might take the bird to an avian vet.

If you’re more of a DIYer, you have several options.

Some chicken-keepers can help the hen pass the egg by removing her to an isolated, dark and quiet location away from the flock. Some keepers say their egg-bound hens pass the egg within hours. In addition to this approach, you can submerge the hen’s bottom half in a warm bath and gently massage her abdomen. If the case seems far progressed, it’s possible to remove the egg manually, taking great care not to break the egg in the process.

If you choose to attempt this, do so with another set of hands for assistance.

The best cure for egg binding is prevention. Start with a healthy diet, limiting fatty treats such as scratch in the summer, and providing age-appropriate feeds and making sure the bird has sufficient calcium and phosphorus. Also, allow birds to free-range and exercise.

Avoid using hens that bind frequently as your breeding stock, as they will pass along the trait to their offspring.

Fleas & Flies

Fleas and flies are insects that feed on the blood of chickens and live off the body to breed and perpetuate their life cycles. The European chick flea (Ceratophyllus gallinae) and the western hen flea (Ceratophyllus niger) are the two species most likely to affect North American flocks. 

Both flea types breed in nests, bedding and droppings, and they return to the birds for blood meals.

Black flies and biting flies are larger insects found near stagnant water. Filth flies breed in soggy manure and damp bedding.

What’s the harm in a flea or fly, you wonder? Well, an infestation of either insect can lead to weight loss or slow growth in young birds as well as physical damage to meat birds, and it might affect egg production in laying hens. Heavy infestations of fleas or flies can severely weaken chicks and sick birds, perhaps resulting in death.

These insects can also, of course, carry and spread disease and illnesses between chickens.

Because populations of these two insects are supported by damp conditions, keep bedding, nest boxes and litter dry. Check faucets, waterers and roofs for leaks, and remove all sources of stagnant water.

To control flies, clean the coop thoroughly after removing the litter and replacing with fresh bedding. Improve ventilation on very hot days especially, because flies don’t like moving air. Flytraps hung out of reach of the chickens as well as other commercially available fly-control products can help you control the fly population.

Read more: Check out these tips for controlling ectoparasites on your poultry.


In winter, a hen sleeps with her head tucked under a wing. A rooster does not.

In biting cold temperatures, roosters’ extra large combs are exposed to the extremes, putting them at risk. When frozen, a comb or wattle will appear pale. If you can catch this at the frozen stage, apply a warm, wet cloth. Allow it to dry, then apply food-grade oil.

If it has frozen and already thawed, you might notice it’s bright red and swollen. It might appear painful. At this stage, you can still apply food-grade oil or honey on the appendage to promote healing.

Serious cases of frostbite can leave a rooster permanently ill or even infertile. If you suspect frostbite or serious freezing, watch the rooster carefully, as his injury could weaken him, which can leave him susceptible to pecking from the rest of the flock. If necessary, isolate an injured bird for care.

If the wattle or comb turn black and the tissue is dead, it might need to be surgically removed. 

There isn’t one easy way to prevent frostbite, but you can take several measures to help. For this and many other reasons, make sure your coop is properly insulated but also has excellent ventilation. Monitor chickens closely during the winter, and make sure they always have fresh water.

Keel Cyst

Better known simply as breast blisters, keel ailments are rather common and progress chronically. These blisters appear on the breasts of growing cockerels or particularly heavy-breasted breeds, each one starting as a blister and eventually growing into a thick callus. 

The blister (here’s your warning of something unpleasant to come) is usually filled with a clear liquid, though it can be bloody or contain pus that is cheesy in consistency. Thankfully, mortality is low, and cysts can be prevented by simply keeping your birds in humane and sanitary conditions. 

Breast blisters typically affect birds confined to cages or small spaces, where their breast bones rub or are pressed against wire cages, wire walls or roosts they’re forced to touch. Give your flock the space it needs and deserves, and your birds might never be at risk for keel concerns. Large-breasted cocks can be protected against blisters by padding roosts as necessary. 

As long as a blister isn’t infected, it won’t pose a threat to humans and isn’t contagious between birds. Some experienced chicken keepers treat keel cysts at home by draining the blisters themselves. But for backyard keepers, it’s highly recommended to consult an avian veterinarian should your bird develop a keel cyst.

Marek’s Disease

Marek’s is truly one of the more concerning chicken illnesses to afflict backyard flocks. It’s common, easily spread and almost always deadly, making it a feared and frustrating issue for those who care for chickens.

A neurological illness, Marek’s affects the nervous system as well as the organs and even skin. The disease is caused by six varieties of the herpes virus. It originates in the feather follicle and lives for years in the bedding and litter of flocks. It can be easily spread from flock to flock by walking in a healthy coop with shoes or boots that walked through a contaminated flock. 

Symptoms of a Marek’s case can vary widely. Most notably, a bird will appear paralyzed, probably because of the pressure put on the spinal cord by enlarged nerves and nodules. It might affect a bird’s respiratory system, in which case a sick chicken will gasp or wheeze in addition to having trouble standing or stumbling often. It’s more common in pullets than cockerels, and death occurs usually within two months of the first symptoms appearing.

Prevention is best attained through several avenues. Firstly, practice extremely stringent biosecurity measures, especially when visiting other flocks or farms, buying chicks or handling chickens that aren’t yours. Wash your hands between handling flocks, and keep your coop clean, regularly changing the bedding. The Marek’s disease vaccine is one of the best methods of prevention, though it doesn’t cover all six strains of the virus, in which case, breeding for resistance and keeping a clean coop can help prevent its spread. 

Very few birds survive Marek’s, and those that do are lifetime carriers. If you suspect one of your flock members has Marek’s, separate it immediately from the rest of the flock, and take the individual bird to the vet for testing.

The results should inform your next course of action, which usually includes a deep cleaning of the coop and new biosecurity measures. 

Newcastle Disease

Newcastle is another unpleasant disease, but the mortality rate is much less than other common chicken illnesses and ailments. Newcastle is caused by the highly contagious paramyxovirus and is spread by ingesting the virus, either from the droppings of other birds or shared feed and water. Transfer can also be airborne. 

Newcastle looks like a respiratory disease with the addition of nervous system symptoms. Birds will wheeze and gasp; hens will stop laying eggs. Farmers might see some discharge from a bird’s nasal cavities. A veterinarian can confirm the diagnosis, so take your chicken in as soon as you suspect something. 

Treat afflicted birds according to your vet’s recommendations. Usually, birds must be kept warm, hydrated, fed and comfortable. Survivors of Newcastle will be carriers for as long as 30 days but will develop immunity. 

Prevention is best done by breeding for genetic resistance. Unfortunately, while good sanitation and coop hygiene are imperative for so many issues, it’s not really a factor when trying to prevent Newcastle. In this case, your best efforts might not make a difference.

Lastly, be mindful of touching your face and eyes after handling a bird with Newcastle, as it can transmit a temporary eye infection to humans. 


Omphalitis, an infection in chicks that occurs after the egg sack isn’t absorbed, can cause a young chicken to die as long as two weeks after hatch. Also known as mushy chick disease, it’s caused by bacteria either in the egg when formed or that gets in through the shell. 

Omphalitis is associated with hatching environments that aren’t sufficiently humid, according to Poultry Diseases, edited by Mark Pattison, Paul McMullin, Janet Bradbury and Dennis Alexander. Clinical signs include affected chicks appearing depressed as well as having distended abdomens and a tendency to huddle. Sometimes the navel is visibly thickened, prominent and necrotic.

chicken illnesses ailments
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Pasted Vent

Pasted vent is another chick ailment, one that is deadly if not addressed but very easy to prevent and cure. Also called “pasty butt,” possibly to lighten the situation, pasted vents occur when feces get compacted around the vent and the chick is unable to defecate. It seems like a minor problem, but it’s nothing to take lightly.

Chicks with pasted vents will die if the disorder is not addressed. Check young chicks daily for the first few weeks of life. Thoroughly but gently clean each chick’s pasted bottom with a warm, wet cloth.

In addition to daily care of chicks, make sure they have a low-stress brooder life, availability of fresh water, appropriate brooder temperature and good feed at all times. With these needs met, pasted vents should clear up quickly. 


Pox of the chicken is considered either wet or dry in variety. It’s not related to chicken pox that affects humans, but it manifests in roughly the same way:

  • white, wartlike scabs
  • bumps on the head, face and necks
  • (potentially) bleeding, scablike rough areas on the fleshy parts of the chicken.

In other words, it’s not pretty. 

Unfortunately, pox is a virus that defies your best management practices and is contagious from bird to bird through general contact. If one bird gets it, the whole flock probably will, unless the outbreak is isolated rather quickly. 

Pox can be spread through bites from mites and mosquitoes, so keeping populations of those insects at bay can help tremendously. Mortality is low with dry pox, but slightly higher (as much as 50 percent) with wet pox, so address it early and arrange for the proper treatment from your veterinarian if possible.

As with other chicken illnesses, vaccinations are available.

Sour Crop

Sour crop is a yeast infection in the crop, a part of the esophagus or food pipe at the base of the neck where the initial stages of digestion occur. It leads to thickening of the crop wall and dilation of the crop and can cause a bird to lose conditioning and possibly die.

Sour crop is caused by a disruption of the normal bacteria that inhabit the crop, with an overgrowth of candidia (which is a fungal species) often occurring. The disorder happens mainly to hens. 

In the book So You Want To Start Keeping Chickens?, author Mark Burrows writes that the fungus develops inside the crop and “in turn will cause the crop to get bigger and fill up with some rather evil smelling liquid.”  

Respiratory Infections  

Many common chicken illnesses can affect a bird’s respiratory system (which includes the trachea, lungs and air sacs), be it viral, bacterial, fungal or mycoplasmal infections. Common signs of a respiratory infection in a chicken include:

  • abnormal breathing sounds
  • bluish-purple face discoloration 
  • conjunctivitis
  • coughing
  • dirty wings, from birds wiping their nostrils on them
  • discharge from the eyes 
  • discharge from the nose
  • face and/or wattle swelling
  • gasping
  • inactivity
  • production of thin-shelled eggs
  • reduced egg production
  • shaking head
  • slow growth
  • sneezing 

Scaly Leg Mites

These little gray bugs spend their lives on chickens if they’re allowed to infest a flock, and they’re notoriously difficult to eradicate. Many conventional breeders and keepers suggest quickly culling any infested chickens, as the mites spread quickly from bird to bird.

These mites prefer the featherless areas of the chicken, burrowing under the scales on a bird’s leg shanks. This gives the chicken the telltale look of a scaly leg mite infestation: old, raised, crusty leg scales.

If you see a bird with leg mites, you have several options. As mentioned previously, you can cull the bird, though this isn’t usually a viable option for those who keep their birds as pets. The most extreme medication route involves the chemical treatment ivermectin.

Unfortunately, this treatment brings with it a huge drawback: It’s not known how long the medication remains in the body, so it’s not recommended for meat birds or layers. The middle road is a more natural treatment: coating the legs in a mineral oil to smother the mites and heal the legs. This method is not foolproof, but it’s well worth a try.

Just know that the leg scales might never return to normal, even if you do get the mite population under control. 


A very common upper digestive tract infection, thrush affects about 20 percent of flocks, but thankfully, its fatality rate is less than 5 percent—far better than some other chicken illnesses. Thrush is a highly treatable in fairly young, healthy birds, which can bounce back quickly.

There are important things to know about thrush, including its tendency to come along with other illnesses. Thrush feasts on low gut bacteria, so it’s more likely to appear after a round of antibiotics, which usually follows another illness, such as coccidiosis. 

Thrush occurs when natural bacteria that colonize the gut are thrown out of balance by poor health or antibiotics—pretty much the same thing that happens to humans.

The good news? Prevention is easy and very good practice for your flock: Avoid prolonged exposure to antibiotics, keep birds healthy with a varied diet and offer probiotic-rich treats. Chickens love yogurt and don’t mind apple cider vinegar tossed in their water.

Most importantly, keep the coop clean. The bacteria in which thrush (and other illnesses) thrives is transmitted through chicken droppings in the drinking water.

Treatment for thrush is simple but has several components: Clean infected areas, treat drinking water with Epsom salts or apple cider vinegar, and clean mouth sores in the chickens, if necessary. Infected birds should, of course, be isolated for the duration of treatment.

Also consider further medication, such as nystatin, if the case is severe. A trusted avian veterinarian can guide you.

One last word: Practice good sanitation with yourself after handling a bird with thrush. The same bacteria that infects the bird can cause human health risk in the form of mouth and genital infections.

We hope you learned a lot about keeping your flock healthy from illnesses in our chicken health handbook. If you have more health-related questions about your birds, search in the field at the top of this page. Good luck raising happy, healthy chickens. 

This article originally appeared in the January/February 2023 issue of Chickens magazine.

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