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Why Do My Chickens Keep Dying? (And Is It Preventable?)

Why Do My Chickens Keep Dying? (And Is It Preventable?)

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The purpose of this blog is to share general information and is written to the author's best knowledge. It is not intended to be used in place of veterinary advice. For health concerns, please seek proper veterinary care. In addition, as an Amazon Associate I earn from qualifying purchases.

Chickens are more-or-less low-maintenance farm animals. Yet, they are susceptible to a wide range of infectious, and non-infectious diseases.

Death sweeping a coop’s population is something that’s, unfortunately, quite common. If you’re still new to raising poultry, you’ve probably wondered “why do my chickens keep dying” at least once.

In this post, we go through the most common causes of death in chickens with a brief guide explaining each case.

Why Do My Chickens Keep Dying?

You might know about infamous diseases, like the infamous H5N1 Avian Flu.

Diseases like the Avian Flu come in sweeps and their losses are tremendous. However, there are a lot more health issues that could go wrong when raising chicken.

To keep things simple, we’ve classified the most common causes of chicken death into three categories: infectious, non-infectious, and neoplastic.

Infectious Causes of Death in Chicken

Most cases of coop death trace back to infectious microorganisms. They are easy to spread from one chicken to the rest within a few days.

Necrotic Enteritis

Necrotic enteritis is a bacterial infection of the gastrointestinal system. Often, the causative microorganism is Clostridium perfringens.

C. perfringens is an anaerobic bacterial that releases an endotoxin.

The toxin is embedded in the structure of the bacterium. This means that it’s released even after the bacteria dies.

Since the bacteria disturb the intestinal lining, the chicken may suffer from:

  • Diarrhea
  • Weight loss
  • Disheveled appearance

However, there might not be any significant warning signs to notice until it’s too late.

The pathogen spreads through excreta. A confirmatory diagnosis requires examining a dead chicken’s intestines.

Necrotic enteritis has a mortality rate of about 30%. If caught in time, an antibiotic course can save the remaining coop. Disinfection is also vital to limit the spread.


Infectious bronchitis (or IB) is caused by an avian strain of a coronavirus. It’s highly contagious; within a day or two, the entire coop could fall ill with IBV.

The viral infection causes an increase in the exudation in the respiratory system. It loads up the sinuses and the nasal passages with watery phlegm.

Besides hitting the respiratory system, the IBV can cause urogenital disturbances too. Here’s a list of some of the signs of an IBV infection:

  • Seeking warmth
  • Increased respiratory exudates
  • Decreased egg production
  • Deformed hatching (watery and shell-less eggs)
  • Thirst and frequent urination

If the viral infection progresses to nephropathic damage, the mortality rate spirals up to 25%.

Thankfully, there are live, attenuated vaccinations for Infectious Bronchitis. Check if your coop is liable for the IBV shots and boosters.

Fowl Pox

Fowlpox is a viral infection that results from an avipoxvirus. Unlike the IBV infection, Fowlpox is slow in its transmission and incubation.

The infection spreads through skin contact through scabs and lesions. These nodular scaps on the bird’s head are the number one clinical sign of the disease.

Fowlpox comes in two ways: wet and dry. The dry type is mostly limited to external lesions. Meanwhile, the wet forms lumps inside the mouth.

These lumps can lead to problems in swallowing and even suffocation in extreme cases.

On the upside, the mortality rate from the infection is less than 5%. Overall, it’s not a very worrisome disease, unless your coop is already compromised.

On the downside, there’s no “cure” for the Fowlpox Virus. Any treatment is purely symptomatic and you’ll have to wait the infection out.

Keep in mind that Fowlpox vaccinations are already developed and they can reduce the severity of the infection. The vaccinations are suitable for ages 12 to 16 weeks.

Fowl Cholera

Fowl Cholera is caused by a strain of bacteria called Pasteurella multocida. The disease is known in two forms: acute (lethal) and chronic.

The signs you need to watch out for are:

  • Increased thick, salivary discharge
  • Increased respiratory rate
  • Swollen wattles (that’s the key symptom here)
  • Hemorrhagic lesions
  • Conjunctiva lesions (chronic)

In acute cases, the mortality rate can go as high as 20%. In chronic cases, the risk of death drops to the quarter.

This infection is particularly serious if the pathogen reaches the meninges (the brain covering membranes) or the bones. It’ll probably be too late by then.

The only sure way to confirm the diagnosis is through sampling and culturing. Even with a confirmed diagnosis, antibiotics won’t completely cure a coop of the infection.

Live attenuated vaccines are also available for Fowl Cholera at 12 and 21 weeks.


Erysipelothrix rhusiopathiae is a type of bacteria that causes septicemia in chickens.

The issue with many avian diseases is that they are silent killers. Erysipelas is one of those silent killers with a mortality rate of up to 33%.

It’s highly contagious and within a day the entire coop could fall dead. If you noticed early, a penicillin dose can treat the remaining flock.

Like many other avian infections, confirming the diagnosis requires a post-mortem examination. The bacteria causes enlarged liver, abnormal spleen, and hemorrhages.

Besides the sudden death and the skin lesions other warning signs to look for are:

  • Diarrhea
  • Lethargy
  • Swollen heads

Keep in mind that Erysipelas is a zoonotic infection. Meaning that it could easily affect humans, too.

This infection can spread through superficial skin cuts. In humans, it can cause dermal issues or septicemia.

We recommend using proper PPE and hand sanitization when handling a coop infected with Erysipelas.


Coryza shows up as an inflammation of the face and the respiratory tract. Overall, it’ll look like a severe allergic reaction.

Avibacterium paragallinarum is the causative bacteria behind Coryza. Here are a few ways that A. paragallinarum might manifest in chicken:

  • Conjunctivitis
  • Bronchitis
  • Swollen heads
  • Increased sinus exudates

Coryza is sometimes self-limiting. It’s only deadly when combined with other risk factors or diseases, like Mycoplasma.

However, Coryza is not zoonotic and poses no risk to human handlers.

The management protocol is both symptomatic relief and antibiotics treatment. It’s crucial to start with a combination of antibiotics as early as possible.

With timely vaccination, the mortality rate drops to less than 5%.


Different variations and strains cause Mycoplasma. The M. gallisepticum and M. synoviae are the most common.

Mycoplasma is very common in poultry and its transmission rate is surprisingly alarming. In most cases, the disease is limited to a mild respiratory tract infection.

These are typical symptoms of a Mycoplasma infection in poultry:

  • Loss of appetite
  • Sinusitis
  • Cough
  • Reduced egg production

The same microorganism can cause more serious infections in other birds. In poultry, the mortality rate is generally low.

The severity of the disease can be reduced by broad-spectrum antibiotics, but it’s never a radical solution. Prevention is almost always more effective than treatment.

The offspring of infected chickens can also carry the disease. If you lost a coop to M. gallisepticum, we recommend sanitizing the space.

Then you can get a new batch from a breeder with a healthy flock.


Infectious laryngotracheitis or ILT is a respiratory infection that hits many coops. An ILT infection is fairly easy to diagnose, it causes a bloody cough.

The infection causes airway obstruction. It might progress to suffocation with a mortality rate of 50%.

The thing about ILT is that it stays infectious even after the bird has recovered from the visible symptoms.

You can get a viral vector recombinant vaccine for both laryngotracheitis and fowl pox.

Non-Infectious Causes of Death in Chicken

If your flock is dying, it doesn’t always mean that there’s a viral (or bacterial) infection. There’s a possibility that it’s a non-infectious issue.

Malnutrition and negligence contribute around 10% of all cases of poultry death. Thankfully, these are easier to handle and prevent.

Nutrition (Dehydration, Malnutrition, and Heat Stroke)

When people are new to raising a flock, they might miss important clues about caring for a chicken coop. Always remember to follow a feeding schedule for your chicken and update it as the population increases.

Maintaining a steady and clean supply of water is crucial for the coop’s survival. It’s also important to shield the birds from extreme heatwaves.

Coop Population and Size

People might think they are saving on space by filling their coop to the max. An overcrowded coop can cause:

  • Pestering
  • Reduced egg production
  • Loss of appetite
  • Decreased physical health

Overcrowding is more of an issue in commercial coops and poultry farms. It rarely happens in backyard coops.

It’s good to keep in mind the appropriate dimensions for the flock population. We recommend keeping at least 42 feet per chicken.


Hemorrhagic Liver Syndrome or HLS is a non-infectious disease that causes sudden death in birds. It’s common with fatty feeds and overcrowded coops where the birds don’t have space to roam and burn off the extra fat.

Chicken with HLS will tend to have fatty livers that can bleed out during straining (like laying an egg.

Without further analysis and investigation, it would be hard to know why the bird died. After blood sampling, many hormonal and enzymatic abnormalities could be found.

A selenium-supplemented (0.3 ppm) feed can help with avian HLS. We’d recommend monitoring the birds’ weight regularly to spot any issues early on.

Neoplastic Causes of Death in Chicken

Neoplastic diseases are tumorous in nature, they can either be benign or malignant. Poultry can get leukoses and reticuloendotheliosis.

The chicken population is also susceptible to virus-induced tumors.

Marek’s Disease

Although the disease originates from the MD virus, it’s associated with tumors in its last stages. The virus hits the T-Cell and the peripheral nerves in the bird.

Marek’s Disease is also called Fowl Paralysis. As the name suggests, the main symptom is transient paralysis.

Once the symptoms start, the bird will have a hard time walking and eating, till it eventually dies.

The virus can be transmitted through litter, feathers, and dirt.

So far, we don’t have a cure for MD. Instead, you can settle for getting your flock vaccinated.

How to Protect Your Chicken from Deadly Diseases

Since it’s better to be safe than sorry, you’re probably wondering how you can prevent infectious diseases.

Here are a few handy tips to help you protect your coop:

Early Detection

It’s always good to be vigilant when it comes to raising poultry. Keep an eye out for breathing issues, discharge, diarrhea, and weight changes.

Any dead birds should be removed immediately. When in doubt, consult an expert veterinarian about the possibility and risks of zoonotic diseases.


Biosecurity isn’t only for large-scale farms. Even backyard chickens could benefit from biosecurity.

The first base you’ll need to cover is exposing your coop to new chickens.

A good rule to follow is that you should treat every new chicken like it’s an infected chicken. Be it from another backyard, a wild bird, or from auctions.

Besides being selective about the birds entering your coop, you’ll need to maintain the coop’s state. Sanitize periodically and after every case of infection.

Most importantly, be hyperconscious about suspicious or multiple deaths in the coop.

Your local state veterinary lab can help you confirm the diagnosis. They can also direct you to the best way to dispose of the dead bird.


From day one, you should vaccinate all your farm animals. Backyard chickens have a very simple vaccination schedule for basic diseases.

Final Thoughts

The answer to the question “why do my chickens keep dying” can be a bit complicated but you can narrow down the possibilities.

We can look at causes of chicken death as infectious, non-infectious, and neoplastic. Infectious diseases are the most common and usually highly contagious.

If a new chicken has recently entered the coop, suspect infectious diseases. You can focus on non-infectious diseases if you find blind spots in your coop maintenance.

Early detections, biosecurity, and prompt vaccination are your weapons against many deadly chicken diseases. Remember that it’s hard to accurately diagnose bird diseases until it falls dead.

One last thing to keep in mind is that birds are sometimes carriers. They may seem healthy but that doesn’t mean that they don’t carry the infection.

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