Chicken Health A to Z (Part 5): Know the Ailments That Can Affect Your Flock

In the fifth part of this series, we continue alphabetically through chicken ailments, covering omphalitis, pasted vent, pox, rations, reproductive health, respiratory health and sour crop.

by Kristina Mercedes Urquhart
PHOTO: Kristina Mercedes Urquhart

In this edition of chicken health A to Z we continue through the alphabet by discussing chicken ailments, including those involving reproduction and respiratory health, pox, omphalitis and pasted vents.

That last two chicken ailments are specific to chicks, whereas some of the others are encountered by adult birds in the fall. If your birds have been deficient in certain areas, such as reproductive health, throughout the summer, you’ll see it manifest later in the year.

Here’s a look at some of the important health topics that fall between the letters O and S. (Read the other installments of the series here: Part 1, Part 2, Part 3, Part 4, Part 6.)


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.

“There is no specific treatment for omphalitis,” write G.D. Butcher, J.P. Jacob and F.B. Mather of the Institute of Food and Agricultural Sciences at the University of Florida Extension in “Common Poultry Diseases.” Most affected birds, the write, die in the first few days of life. “Unaffected birds need no medication. … Control is by prevention through effective hatchery sanitation, hatchery procedures, breeder flock surveillance and proper preincubation handling of eggs. Mushy chicks should be culled from the hatch and destroyed. If chick mortality exceeds 3 percent, the breeder flocks and egg handling and hatching procedures should be reviewed.

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chickens hen chicken chicks

Pasted Vent

Pasted vent is another of the chicken ailments that affects chicks, 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, through white, wartlike scabs; bumps on the head, face and necks; and 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. Vaccinations are available.

“Several species of mosquitoes can transmit fowl pox and play a significant role in spreading the virus from one flock to another,” writes Jacquie Jacob of the University of Kentucky in “Fowl Pox in Poultry.” “Mosquitoes ingest the virus when they feed on birds with fowl pox virus in their bloodstreams. The insects then spread the virus when they feed on healthy birds. Mosquitoes are the primary source of infection on poultry ranges. Mosquitoes often winter over in poultry houses, so outbreaks can occur during winter and early spring.

“Fowl pox is also spread from bird to bird through direct contact. The virus is airborne and can infect birds through their eyes or skin wounds or when they breathe. Although the disease is contagious, it spreads slowly.”

chickens run coop


At any stage of life, proper rations are a must. When we keep domesticated chickens in our care, they rely on us for good nutrition. Many people advocate letting chickens graze and spend time on pasture as much as possible, but our domesticated birds have been bred to be high producers of eggs and meat. Because of their modified genes (which we humans have altered), they need a nutritional boost to for optimal health. Thankfully, it’s getting easier to find high-quality, organic, affordable chicken feed.

Young chicks require feed that contains more protein than that of their adult counterparts: Look for feed called “starter” feed. This ration might come medicated for coccidiosis, and it’s worth researching this topic further to choose which feed is best for you. Some starter feed rations double as broiler feeds, in which case contacting the manufacturer and reading the label closely will help you find the right match.

Adult, actively laying hens should be offered “layer” feed, which is formulated with more calcium and less protein. Meat birds require “broiler” feed in addition to pasture time, and roosters will eat pretty much anything.

In moderation, treats are a wonderful addition to a flock’s collective diet, as long as they’re fresh, not rotten or moldy, food, and preferably greens. Garden and kitchen scraps destined for the compost are often delightful chicken treats. Scratch, dried mealworms and other packaged treats are available commercially but should be treated as “chicken candy,” rather than a meal replacement.

Reproductive Health

Even if you’re not a breeder or never plan to breed your birds, you should pay close attention to your flock’s reproductive health. Even if you keep chickens only for the joy of having them in the yard, they still lay eggs almost daily, and their reproductive health mirrors their health as a whole.

All mature female chickens, called pullets, lay eggs. A rooster need not be present for a hen to lay eggs. Consider egg laying the menstrual cycle of the chicken. Instead of monthly, though, as it is with humans, it occurs daily. If you want to hatch chickens, you need a rooster to fertilize the eggs. All eggs, fertilized or not, are edible as long as they are fresh.

A hen’s reproductive system is a busy system indeed. A lot goes right most of the time, but a lot can go wrong. Laying an egg per day is hard work. Most hens lay in the morning hours, and it can take 30 to 45 minutes of sitting to lay one egg. For the health of your hen and the safety of your eggs, a laying flock should have access to nest boxes that are dark, soft, dry and safe, with ideally one box per four to five hens.

Optimal reproductive health requires good nutrition. Laying hens should be able to move about, peck and scratch, forage for food at times, and be offered a nutritious, high-quality feed. Water should be available at all times. Laying hens also require dietary supplements for healthy reproduction—namely oyster shells, as an added source of calcium, offered free choice for the birds to take as they need.

What to Look For

When reproductive issues occur, they can progress rather quickly, so it’s best to know what to look for. One of the most common reproductive chicken ailments is a nutrient deficiency. You’ll know a hen is struggling with calcium if her eggshells are soft, have odd deposits or rough spots, or if there is no shell at all. Offering oyster shell, and increasing the quality of the feed, quickly solves the problem in most healthy birds.

More serious issues are ovarian in nature and include blockages of the vent or struggles to lay. Egg binding is a grave ailment that can turn deadly if not prevented or properly managed. This occurs when an egg remains lodged in the oviduct and the hen cannot pass it.

Prolapsed oviduct occurs when the oviduct turns inside out and appears outside the vent. This ailment is also called “blowout” or “pickout” because the other hens tend to notice and cannibalize the afflicted hen. In both cases, you should isolate the hen immediately and take measures to remedy the situation. In some cases, taking the bird to an avian veterinarian might be necessary.

chickens free range

Respiratory Health

Chickens, like all birds, are notorious for having extremely sensitive respiratory systems. This is partly because of their porous air sacs and the fact that their respiratory systems are unusual. As a chicken-keeper you need to know that volatile organic compounds, or VOCs, in the air can affect your birds, and you must take measures to keep the birds safe from hazards.

Respiratory chicken ailments are fairly common in chicken flocks worldwide, and these conditions can turn chronic in the winter when birds are more likely to be cooped up indoors. Usually caused by a virus, they can also be nutritional, parasitic, bacterial or environmental in nature. In any case, your best bet against respiratory diseases and infections is prevention on all fronts.

What to Do

First, breed and keep birds with good resistance; try to avoid carriers of chronic infections. Next, practice good hygiene, particularly when it comes to ventilation in the coop. Strong ammonia smells from chicken waste can exacerbate respiratory sensitivity. Third, provide excellent quality organic feed, with fresh water at all times. A healthy gut and a healthy diet keep the immune function strong and reduce the likelihood of viruses.

Some respiratory diseases are the result of vaccinations, so research the vaccines you choose to implement to the best of your ability.

Finally, what you can control the most is exposure to VOCs. Unless absolutely necessary, never paint the interior of a chicken coop. It invites many potential problems, such as chickens picking at the paint. (They’ll pick at anything.) Also, the off-gassing of the paint attacks the respiratory system. Paint with high VOC levels is known to be the most potent in off-gassing for the first two weeks. But it continues to off-gas for several years.

Reduce odors, particularly chemical or artificial odors, in other ways, too. For example, don’t wear perfume while holding chickens, don’t spray perfume or aerosol around the coop, and use common sense with other olfactory offenses.

Your chickens will thank you—maybe not in words, but certainly in health, long life and copious amounts of eggs.

Respiratory Infections

Many common chicken ailments can affect a chicken’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

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.”

In The New Rules of the Roost, authors Robert and Hannah Litt write that sour crop can be prevented by supplementing with probiotics and prebiotics as part of a daily regimen, regularly refreshing your clock’s water, and keeping the chickens’ areas cleared of fallen fruit. “We love to give our chickens leftovers that seem too good for the compost heap, but we always make sure the food is not at all moldy,” they write.

Thanks for joining me, and stay tuned for the final installment, where we’ll address chicken ailments T through Z.

This story originally appeared in the September/October 2018 issue of Chickens magazine.

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