raising happy, healthy chickens

What Are The Most Common Chicken Diseases?

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If you have a backyard flock, you might be one of the lucky ones whose birds haven’t experienced any chicken illnesses. Yet. I say yet, because just like people, chickens can and do get ill. In this post I’ll cover the most common chicken diseases. And I’ll go over preventative measures, and if contracted, how to treat the bird.


Fowl pox is usually transmitted by biting mosquitoes or new birds who are carriers of the disease. There are also 2 forms of this disease: Wet pox and dry pox. Wet pox is deadlier than dry pox, because wet pox causes throat and respiratory spots that may develop into large growths. These growths may make it difficult to eat, drink, and breathe. With dry pox, there are white spots on the combs, feet, and waddles. It can look like your bird has been pecked mercilessly. At first, you might just think that’s what it is; that your birds were pecked. However, if you have more than a couple of birds like that, and their egg production is down, you just might have birds with fowl pox.

It was a couple of years ago that one of our Black Sex-Link hens died suddenly, out of the blue. Naturally that had us concerned. My husband did a semi-exam on her, but he’s not a vet. We couldn’t say for certain her cause of death. She did, however, have bumps in her mouth, which was strange. Previously we never noticed any odd behavior from her — it was so abrupt. So, we started examining the rest of our flock and discovered some white spots on the combs of a few of our birds.

We separated the 3 hens from the rest of the flock, not knowing at the time what the issue was. Maybe a day or two later, the separated hens started developing sores around their beaks. And in time we realized the hens with the white spots on their combs had fowl pox. Chicken pox for chickens, as I call it; it is not contagious to humans.

Initially we were advised to euthanize our flock. That’s the preferred method most people take with birds, because there aren’t a lot of poultry vets. And illnesses spread so quickly. Plus, if you look at the literature out there, everything says they’ll die. It’s very dismal, but we were very adamant against doing that.

Sketch of Chicken with Fowl Pox Courtesy of Hannah Smith

Perhaps your birds are your pets. Like us. Or maybe they are a small source of income. I’m willing to bet you get some joy out of your backyard flock. Some reward. It’s not easy putting an animal down. Especially if you aren’t sure it’s really necessary.

Treating Fowl Pox

The lesions of fowl pox heal in about 2 weeks, so they need to be separated from the others. You should inspect the rest of your birds to look for any spots. Or you can order the vaccine and administer it to the rest of your flock. Just in case. In the event that you need the vaccine, you may wonder if the eggs are safe. That’s a great question, because there’s not a lot of literature out there. With de-wormers you’re supposed to go 2 weeks each de-worming, not collecting the eggs. Well, you get the eggs but don’t eat them.

We kept our three hens separated for the requisite time period. We prayed for the rest of the flock, and in the meanwhile, I ordered the vaccine for my remaining birds. Once a bird has fowl pox, if they live, immunity is supposedly life-long. It’s a slow-spreading disease, which is the main reason why I ordered a vaccine; I didn’t want to wait and see what happened to the rest of my birds. We didn’t eat the eggs. It’s better to be safe than sorry. I know now that the Black Sex-link must’ve had the wet pox, while the other three had the dry pox. I’m thankful none of the other birds contracted the illness, because quarantine is a long time away from the flock. And I’m happy to report that the other 3 hens recovered.


Another common chicken disease is coccidiosis. It’s a parasitic illness caused by coccidian protozoa, primarily affecting birds when they are younger. This is generally why medicated feed is offered, at least here in Oklahoma. Adult chickens can also get coccidiosis. Although, they are more resistant due to earlier exposure to infection, according to Merck Manual. Signs of infection are decreased growth rate, severe diarrhea, death, and if adults, decreased egg production.

Treating Coccidiosis

I already mentioned medicated feed for chicks, but if you have an adult bird with coccidiosis, there’s Amprolium. It’s the same treatment in medicated chick starter, which blocks the parasite’s ability to uptake and multiply. You should keep brooders and coops clean and dry. You also need to make sure waterers are clean and don’t overcrowd the coop. Also, don’t throw feed and treats on the ground. If you have waterfowl with chickens, make sure the coop is clean and dry, and change the water often.

Anatomy of a Chicken Courtesy of Paul Smith


Egg binding is another common issue that can affect hens. Symptoms may include

  • Loss of appetite
  • Disinterest in drinking
  • Decreased activity
  • Shaky wings
  • Walking like a penguin
  • Abdominal straining
  • Uncharacteristic sitting
  • Passing wet droppings or none at all
  • Droopy, depressed, or pale comb and wattles
  • And presence of an egg in the oviduct upon an examination.

Being egg-bound simply means a hen has an egg stuck inside of her that she cannot pass. Or the hen is having difficulty laying the egg. There are different reasons this happens:

  • Lack of calcium, which is what puts the shell on the egg and helps the hen’s muscles contract and push the egg out
  • Obesity- a chicken that is obese can have a difficult time laying an egg, because her muscles are weaker and can’t contract as strongly as they should
  • Infection- sometimes a chicken will have an infection in their reproductive tract. They may have no symptoms at all, but it can still cause all kinds of issues including muscle weakness
  • Malformed eggs- eggs that are very big or misshaped can be problematic for the hen as well
  • Stress- stressors such as a new coop or flock can cause problems for a hen
  • Premature laying- sometimes a hen that starts laying eggs too soon might get egg-bound because they are too young.

Treating an Egg-Bound Hen

How do you treat an egg-bound hen? First, you have to make certain there’s an egg by inserting a gloved finger (coated w/Vaseline) into the suspected hen’s vent to a depth of 2 inches. If you can’t find an egg, there isn’t one. However, if there is one, then fill a tub with warm water, and add 1/2 cup of Epsom salt to every 1/2 gallon of water. Then immerse the hen gently into the water till her abdomen and vent area are soaking. You must be careful, because you don’t want the egg to break; that would be another issue entirely. Keep the hen in the tub for 20 minutes at least before removing her and drying her off.

Keep her separated from the other birds to hopefully encourage laying the egg; you can also lubricate her vent with Vaseline to help the egg slip out. If after her first bath she hasn’t laid the egg in a couple of hours, repeat the bath. In the event you still no have no success after 3 or 4 baths, you might need to contact your veterinarian. If you can feel the egg, you might be able to remove it in pieces, although it’s not generally recommended, because it can lead to injury and infection.

You can try to prevent egg binding by managing your flock’s diet, giving them the appropriate feed. A chicken feed with 16% protein should contain all that your flock needs, including calcium, however oyster shell should also be available. Controlling worms is another prevention method as is making sure you have enough nesting boxes. Try to reduce stress by eliminating or minimizing changes in coops or flock mates. You can decrease premature laying caused by added lights to the chicken coop by monitoring light exposure until pullets reach maturity around 20 weeks. There isn’t a whole lot to be done about large and misshapen eggs. Sometimes it’s just a one-time thing, though if it becomes habitual that the hen routinely lays large eggs, she needs to be monitored for vent prolapse, which will need to be treated quickly.

Rhode Island Red hen we thought had gapeworm
Jango, the hen I thought had gapeworm.


Gapeworm is another problem your birds might come into contact with. It causes respiratory problems in chickens. But what is gapeworm? It’s a parasitic nematode that infects the tracheas of domestic and wild birds worldwide. If your chicken is infected with gapeworm, they will gape. Or they will stretch their necks out to adjust their crops and shake their heads. They also cough, all in an attempt to dislodge the parasites.

Treating Gapeworm

I have read where you could swab your birds throat to know if they have gapeworm. The worms will appear as thin red strings. If your bird is infected with gapeworm, they need a de-wormer like Ivermectin. Although, you can prevent gapeworm by keeping the environment clean and dust-free. You also need to till the soil in the run at the end of the growing season, which is supposed to reduce residual infection. And keep up with the worming schedule.

If your birds are stretching their necks, it doesn’t necessarily mean anything. Chickens will stretch their necks out to adjust their crops; I’ve seen my birds adjust theirs after they’ve been eating a lot of food. Are they coughing and gasping? Has their egg production decreased?

Sketch of a Chicken Mite Courtesy of Paul Smith


Your birds might get infested with either mites, lice, or worms. Or other critters not specifically mentioned. Anything parasitic is bothersome to chickens and could even be deadly. And the treatments and preventions are different.

If your flock has a problem with mites or lice, generally they won’t lay as many eggs. Their combs and wattles will be pale, and they can get anemic. And the problem can even cause feather loss, mostly on the back. Because, the hen will want to over-preen and possibly pluck her own feathers, just to get relief.

Mites and lice can be treated and prevented pretty much the same way, although ticks need a different method. Our birds have had mites, and the natural method is diatomaceous earth, which is supposed to be a cure-all for everything for poultry. But we haven’t had great success with it. I think the first time our chickens were free of mites was when we applied Ivermectin last Spring. It is recommended to treat the birds topically for lice and mites, but for ticks the recommendation is to treat their coop and surrounding area. We have bees so it’s often difficult to find products that actually work that are also safe for the bees.

dewormers for chickens


There are mixed reviews for natural de-wormers out there. A lot of people recommend using apple cider vinegar and garlic. There are probably more natural ingredients than those that could be used. And I’ve used apple cider vinegar and garlic since having chickens. However, this past Spring our birds all got the yucky anyway (not gapeworm). We had to administer Ivermectin after I ordered Wormout gel from Australia. It was going to take several weeks to arrive, and I was impatient to treat my birds. With Ivermectin you just apply the treatment topically, while Wormout gel is added to their water. (I didn’t dose my chickens with the other when it arrived.)

I have read many reviews and spoken to fellow chicken owners who have tried the natural methods as well. Birds, just like any other animal, just like you and me, will still get ill no matter our best laid plans. Sometimes we have to take the stronger stuff. I haven’t administered any more “strong stuff”, because I haven’t seen any indication that I need to. I continue to put ACV in their water once a month; (1 TBSP per 1 gallon each day for 1 week X once a month. Since we have ducks I add Brewer’s yeast, which has the garlic in it. So I don’t have to add any extra.

Either Ivermectin applied topically (0.2 – 0.4 mg per kg topically at their shoulders where they can’t reach and once more in 2 weeks,) or Wormout gel added to their water (2 pumps of the gel per 1 1/3 cup of water) are the best options if there is an infestation; remember you shouldn’t eat or sell any of the eggs from your flock till the treatment is ended. Ivermectin dosing is 2 times in one month, so you can’t eat the eggs for 2 weeks each dosage. And since Wormout gel dosage is just once in their water, you only go 2 weeks refraining from eating and selling the eggs. After that, start a monthly preventative of 1 TBSP ACV per 1 gallon of water daily for 1 week with garlic sprinkled in their food.

Mixed Backyard Flock at Backdoor of House
Our boss hen Fives, the Silver-Laced Wyandotte, close to the front.


Avian flu, or more commonly bird flu, is a chicken illness that is often heard of at least yearly. Symptoms include a general decrease in roaming and activity. Your birds will present with cyanosis or blueness in the head area. They won’t eat as much, and there will be excessive flock huddling and ruffled feathers. They might have fluid in their combs and wattles. There will also be a decrease in egg production and coughing. Their legs may bleed underneath the skin, and they may die suddenly.

How to Treat Bird Flu

You might not completely prevent your birds from getting bird flu. However, there are things you can do to protect them. Don’t encourage wild birds from stopping by your yard by feeding them, and keep your feeders and waterers clean. Bird flu, just like other bird illnesses, can spread by wild birds.

  • Clean out the coop on a regular basis
  • Have dedicated clothing and footwear you use when handling your birds.
  • Make sure not to wear this when anywhere else but around your own birds, especially when around other chickens. Bird flu can live on clothes that have been contaminated by an unhealthy flock for up to two months.
  • Pick up feed spillages to avoid attracting wild birds.
  • Also, don’t borrow or use equipment from other people who own chickens.
  • And clean your own equipment with which you used to transport your birds or clean out their coops.
  • Monitor your flock’s behavior, appearance, and appetite.

Avian flu is highly contagious and deadly to birds and humans. Although, there are vaccines for human. Failing that, if bird flu is still contracted, antivirals can be administered within 2 days. The only recommendations there are for birds who catch this disease are euthanizing the whole flock, appropriate disposal of the carcasses, and sanitizing the coop.

Sketch of Chickens with Marek's Disease Courtesy of Hannah Smith
This is a sketch of Marek’s Disease.


Another illness in backyard birds is Marek’s disease. Symptoms of this are paralysis of legs, wings, and neck, loss of weight, grey iris or irregular pupil, and vision impairment. It is one of the most common illnesses in small flocks and not treatable once the clinical signs have started, however it is preventable.

Marek’s is caused by a chicken herpes virus, but it won’t make people sick. Once an animal becomes infected, it will remain infected. However, not all animals will become sick if infected. Birds become infected by inhaling virus-laden dander, and while the virus is easily killed in it’s pure form, the virus itself can live for years in the dander. That means that once the disease enters a coop, it can live for a very long time, years, even if the birds are all gone. The only way to prevent this disease is to vaccinate day-old chicks before they’re exposed to the virus. Unfortunately not all hatcheries will vaccinate their chicks; the vaccine itself is tricky and has to be used within very specified conditions for it to be effective.

Black Ameraucana hen that died with vitamin deficiency
Our trio of Black Ameraucana’s. Shockwave is the one closest to the front.


Vitamin deficiency is something to note here, because it can mimic Marek’s disease. A couple of years ago, we think Megatron, our boss rooster, injured one of his hatchery-mates. He decided he wanted some ‘lovin’, and he’s not very coordinated when it comes to mating. Thus, he injured his hatchery-mate, Shockwave. We noticed she stopped using one of her wings. Eventually she stopped competing for food, I think because she was afraid of getting hurt further by the other birds. She’d hang back until there was less competition. At the time we didn’t realize what was going on. We knew she was hurt, and we surmised it was due to Megs. But we didn’t realize she was waiting on food, because she was always there when food was being dished out. Over the course of a couple of weeks she started to get weaker, until she was no longer walking.

Sketch of Hen with Vitamin Deficiency Courtesy of Hannah Smith
This is a sketch of our hen Shockwave with vitamin deficiency, but I’ve seen many more photos of birds that look a lot worse.

We thought it was Marek’s due to the paralysis; Hannah, my 18 year old, was convinced, but I’d remind her that Shockwave was injured originally. Marek’s didn’t make sense or fit. Something was missing. So I continued researching the matter until I came across vitamin deficiencies that mimic Marek’s. I went to the store and purchased Poly-Vi-Sol infant liquid multivitamin and immediately started administering it to Shockwave. Unfortunately it was too little too late; she died the following day. I felt horrible, because I thought I knew what was going on in my flock and yet she died. I felt it was completely preventable. My point in sharing this story with you is that Newcastles Disease and Marek’s Disease mimic vitamin deficiency in the presentation of paralysis, so it’s vitally important to look at all of the signs. If we had acted sooner we could have saved our hen.


Newcastle Disease is another respiratory illness in chickens which causes breathing problems, discharge from nares (nostrils on a chicken). If your bird is infected with Newcastle disease, their eyes will look murky, egg laying will begin to wane, and wings can become paralyzed as well as their necks becoming twisted.

Sketch of Chickens with Newcastle Disease Courtesy of Hannah Smith

This disease is also carried by wild birds, and just like bird flu, it can remain on your clothing and be passed to your flock. Although most older birds will recover, younger birds are at an increased risked from dying from it. Even though there are vaccines available to prevent this disease, there is no treatment for it except antibiotics for secondary infections and supplements. Also like bird flu, Newcastle disease can be spread to people, though it isn’t deadly. It produces either no symptoms at all, mild flu-like symptoms, or conjunctivitis or pink eye.

All of the sketches in the post courtesy of Hannah Smith.


I breed pure Black Ameraucana chickens and Easter Eggers that are Black Ameraucana mixed with either Cuckoo Maran or Barred Rock. And I donate eggs to people or organizations in need.

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