Why Is My Chicken Laying Weird Eggs? Wrinkled, Rough, Ridge

You go to collect eggs, and one looks decidedly wrong. The shell is wrinkled, rough like sandpaper, flat on one side, or has a thick ridge around it.

The first thought is always that something is wrong with your hen, and sometimes there is, but a few odd-looking eggs may not be cause for alarm.

An eggshell is formed within the hen, and there are many reasons why a single egg may be malformed in some way.

A young pullet may be adjusting her laying cycle, an egg may have stayed in her shell gland for too long, or two eggs may have been in her reproductive tract at the same time.

The formation of the shell can be affected by stress, and some diseases leave telltale shells as well.

Check the hen, not just the egg, and take note of the next few eggs she lays. One oddly shaped egg from a hen who otherwise lays normal eggs is not the same situation as multiple hens suddenly laying malformed eggs while their regular rate slows down or stops.

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First, Check Whether the Shell Is Actually Hard

Before doing anything else, pick up the egg and test the shell. A wrinkled or bumpy egg that is hard is not the same issue as an egg that is soft, squishy, or has a thin spot.

If the shell is not hard, see our article on soft-shelled eggs in chickens, as this is a separate issue. Here we are focusing on eggs with an abnormal shape, including wrinkled, ridged, or pimpled shells, a flat or slab-sided appearance, or other issues.

Wrinkled Chicken Eggs

A wrinkled egg has folds or ridges in the shell, which may range from a few bumps to a generally creased appearance.

Stress can be a cause if the hen was frightened or handled roughly, if there has been a predator loose, or if she was otherwise troubled. Other causes include issues in the shell gland, such as infectious bronchitis, but again, a few wrinkled eggs are not always a problem.

If the rest of the hen’s appearance and the following eggs are normal, watch and wait rather than jumping to conclusions about her health.

Can a Sudden Fright Cause a Wrinkled Egg?

It can contribute, but it is not the sole cause. An egg takes hours to form inside the hen before it is laid, so a disturbance while it is forming can lead to a wrinkled egg or other issues.

If there has been a predator nearby, if you have done something that startled the flock, or if you have recently handled the birds, stress is a potential cause. However, it is not the only reason for abnormal egg formation, nor should it be used as an automatic diagnosis for every odd-looking egg.

Infections such as infectious bronchitis are serious, so if other symptoms are present, it is best to contact a professional.

Rough or Sandpaper Chicken Egg Shells

Sandpaper shells appear almost normal until you feel them, at which point you notice small bumps all over the shell. These are also sometimes called pimpled eggs, and the cause is generally foreign material in the shell gland or extra shell formation due to an egg taking too long to pass.

Does a Sandpaper Egg Mean Too Much Calcium?

Not necessarily. It is a common misconception that an oversupply of calcium in the flock’s diet will cause this issue.

A sandpaper egg can be a sign of extra calcium, but extra calcium is not always the cause. Shell-gland timing, stress, disease, lighting schedules, double ovulation, and other factors can lead to the same symptoms.

Do not remove oyster shell from your entire flock’s diet based on a single sandpaper egg, as laying hens require calcium to put into their eggshells. See our oyster shell for chickens guide for more information about supplemental calcium.

Small Calcium Bumps on the Shell

Sometimes the bumps on a shell are not uniformly distributed throughout the egg but are instead a few hard white or brown spots that you can feel when running your fingers over the shell.

A few bumps on an egg are generally not a cause for alarm, but if the same hen lays multiple pimpled eggs, check her age, feed, laying patterns, light exposure, and stress levels. If she is a young pullet just learning to lay, or if another cause can be identified, it may simply be a matter of time before she gets back to laying normal eggs.

Flat-Sided or Slab-Sided Eggs

A flat-sided egg will have one side that looks squashed and the other rounded out in a normal appearance. The technical term for this is slab-sided, and it generally occurs when a hen has two eggs in the shell-gland area at the same time.

Why Do Two Eggs End Up Together?

It usually happens because of double ovulation, but other factors can include stress, light exposure, and crowding. Two eggs may reach the shell-gland area close together, and one can end up with a flattened or slab-like appearance from pressure against the other.

If you have a new layer who only laid one slab-sided egg but otherwise seems normal, there is generally no cause for alarm. However, if she continues laying malformed eggs or if other hens begin doing the same, there is a different set of potential issues.

What Is a Ridged Egg?

Not every ridge around an egg is a sign of the same problem. A thin line may simply be an irregularity in the shell, but a thick ridge is generally what is called a body check.

A body-checked egg is one that has been damaged while inside the hen and has extra shell material laid over the damaged portion before being expelled. These can look almost like repaired cracks, but the ridge of the repair is what shows in the shell of the egg in the nest box.

Are Ridged Eggs Dangerous?

As with most eggshell abnormalities, the ridge itself is not generally dangerous, but it can be a symptom of other issues. Heavily ridged or otherwise deformed eggs sometimes have spots of thin shell that are weaker and more likely to crack.

Check the egg before placing it in with the rest of your collection, and if you are unsure whether a ridge is an abnormality or a full crack, use an egg candler to check.

Ridged or otherwise deformed eggs are poor choices for hatching, but if the shell is otherwise intact and free of cracks, the unusual shape alone does not make the egg unsafe to eat.

Wrinkled Egg or Corrugated Egg?

There is not always a clear difference between a wrinkled egg and a corrugated egg, although the terms are sometimes used for slightly different abnormalities. A corrugated egg generally has more pronounced ridges and may even look somewhat like crumpled paper.

Issues with the plumping process before shell formation are sometimes linked to these types of eggs. Older hens are generally more likely to lay them, although younger layers can do so as well, and heat stress, salt, nutrition, and mycotoxins are some of the possible causes.

Young Pullets Lay More Weird Eggs

If you have young pullets who are just learning to lay, it is not unusual for them to lay one or two oddly shaped eggs before continuing with their normal laying patterns. If you want to know what is normal at the start of lay, see our guide on when chickens start laying eggs.

They may be smaller or larger than normal eggs, have bumps or ridges on the shell, be oddly shaped, or even have two yolks. One strange egg from a young pullet who otherwise seems normal is very different from a large number of strange eggs appearing across a group of birds.

Older Hens Can Lay More Shell Defects Too

The same goes for older hens, although in this case age is one possible reason. Older hens generally lay fewer but larger eggs, and their shell formation can become less consistent.

It is not unheard of for an older hen to lay a strange egg every so often, but again, it is a matter of pattern. If the rest of the flock seems normal and only one older hen lays a malformed egg every few weeks, it is not an immediate cause for concern.

If several hens begin laying strange eggs around the same time, however, it is best to look into the issue further.

When Weird Eggs May Point to Infectious Bronchitis

This is where looking at the bigger picture comes in, as far too many people have looked at a single strange egg and jumped to the conclusion that their laying flock has infectious bronchitis.

The problem with infectious bronchitis is that it can lead to wrinkled, rough, pale, thin, malformed, and generally abnormal eggshells, but a single abnormal egg is not enough to suspect or confirm the disease.

If you have a number of hens who have begun laying abnormal eggs and their laying rate has dropped at the same time, it may be worth looking into. Coughing, sneezing, and other respiratory signs can also occur.

Infectious bronchitis is serious, so if you suspect it, contact a poultry veterinarian rather than trying to diagnose the flock from the eggs alone. Our guide to keeping chickens healthy can help you check the rest of the flock while you decide what needs attention.

Stress Matters, But Look for the Source

People often say that their hens were stressed, but this does not generally explain exactly what happened.

If something did happen, it is important to identify and address it. Did you move the flock or add new birds to the coop? Did the hens have a predator loose nearby?

Did you change their lighting schedule? Are the birds crowded or uncomfortable? Is there a sick hen that the others are avoiding?

Identifying the source of stress can help you eliminate it, and calling every abnormal egg a stress egg is not always helpful.

Check the Water Supply

The water supply is something that is often overlooked when addressing a strange egg.

A laying hen requires constant access to clean, fresh drinking water throughout the day. If the water runs dry, freezes, becomes clogged, or is otherwise out of reach for some of the flock, it can affect egg production and quality.

Always make sure the waterer is in good working condition and that all of the hens have access to it. Lower-ranking hens in the pecking order may be unable to get enough water if they have to compete with dominant birds.

Check the Feed Before Adding Supplements

A laying hen needs a balanced diet if she is going to produce normal eggs on a regular schedule. If you have been feeding layer feed and then suddenly switched to scratch grains or another type of feed, it can throw off the balance of her diet.

Layer feed should make up the majority of a laying hen’s diet, with treats like mealworms and vegetables supplied separately. If too many treats are given and the hen is not getting enough balanced nutrition, it can affect her ability to make eggs with normal shells.

Do not just add extra calcium or other nutrients if she is eating a diet that is not suited to her needs. See our guide to nutritional deficiencies in chickens for more information about what can happen when a complete ration gets diluted.

Should You Add More Calcium?

Only if there is a legitimate reason to do so. A calcium deficiency can certainly lead to a number of eggshell issues, but so can other causes.

A rough or pimpled shell may have extra calcium deposits, a slab-sided egg can form when two eggs are in the shell-gland area together, and a body-checked egg has a repair line that runs along the shell. Extra calcium will not necessarily fix these issues, so it is best to observe the rest of the flock and the following eggs before making any changes.

If the hens already have access to a calcium-appropriate layer feed and oyster shell, it is unlikely that a single strange egg means they need more.

Can You Eat a Wrinkled or Rough Egg?

A wrinkled or rough egg is not necessarily something that cannot be eaten; it depends on the condition of the shell.

The most important factor is whether the shell is intact and clean. A rough or wrinkled shell is generally a shell-quality issue, but a cracked or leaking shell should be treated like any other damaged egg.

Do not assume that a rough shell means the egg is spoiled, but also do not treat a broken shell like an intact one. Store sound eggs appropriately and cook them thoroughly, and see our fresh egg storage guide for more information about storing and using eggs.

One Weird Egg vs. Ten Weird Eggs

This leads into the most important distinction for most egg-related issues, and it can usually be summarized in one phrase: one strange egg versus ten strange eggs.

If your young pullet lays one strange egg and then goes back to laying normal eggs, it may be a one-time issue that does not occur again. On the other hand, if many hens suddenly begin laying strange eggs at the same time, it is worth looking into more closely.

There is a world of difference between a single odd-shaped egg and an entire flock of them.

A Quick Nest-Box Check

When faced with an odd-looking egg, it is a good idea to take a moment and assess the situation before deciding what to do with it.

If the egg has a hard shell, is it cracked? Is the shell rough or only wrinkled? Is it flat on one side? Does it have a thick ridge around it? Do you know which hen laid it? Has it happened before? Are the other hens laying strange eggs as well?

Then look at the birds. Check their feed and water and assess whether there have been any recent changes or issues before deciding what to do next.

When You Should Be More Concerned

There are some cases in which a strange egg is an indicator of something more serious.

It is not always easy to tell what is normal and what is not, but there are some general warning signs to watch. Unexplained drops in egg production, coughing, sneezing, abnormal discharge, loss of appetite, lethargy, or strange behavior in one or more hens should always raise concern.

If there has been a recent increase in strange eggshells, especially if multiple hens are affected at the same time, it is also a good idea to be extra careful. Thin, cracked, leaking, or otherwise damaged shells, repeated egg-production problems, and changes in the birds themselves can all point to a larger issue.

Remember that the strange shell may be only one symptom. If the hen’s general health or the flock as a whole looks wrong, see our article about when to call a veterinarian for a chicken.

Frequently Asked Questions

Why did my chicken suddenly lay a wrinkled egg?

Sometimes shell formation simply gets disrupted for one egg. Stress, crowding, shell-gland issues, or infectious bronchitis can all contribute, so watch the hen and see what happens with the next few eggs.

Does a rough or sandpaper egg mean too much calcium?

Not necessarily. The bumps may be calcium deposits, but a rough shell can also happen when the egg stays in the shell gland too long or when laying is disrupted, so one sandpaper egg is not a good reason to remove oyster shell.

Why is one side of my chicken’s egg flat?

This is a sign of a slab-sided egg, and it generally happens when two eggs reach the shell-gland area close together and press against each other while one shell is still forming.

What causes a hard ridge around an egg?

A thick ridge can be a body check, in which the shell gets damaged while the egg is inside the hen. More shell material is laid over the damaged spot before the egg leaves the hen, forming a raised repair line.

Can I eat a wrinkled or rough chicken egg?

If the shell is intact, clean, and the egg is not leaking, the odd shape of a wrinkled or rough egg is mainly a shell-quality issue. If the shell is cracked or the membrane is broken, treat it like any other damaged egg.

Should I give extra calcium after one weird egg?

Usually not. If your hens already eat a complete layer feed and have oyster shell available, watch the next few eggs rather than changing their entire diet, because many shell defects have nothing to do with low calcium.

Final Thoughts

A strange egg can be alarming, but it is generally best to look at the bigger picture. A single odd-looking egg from a young pullet or an otherwise normal hen is very different from an entire flock of strange eggs.

One strange egg is generally less concerning than several, and a few strange eggs are less concerning than a strange egg from a sick or troubled hen. Check the eggshell abnormality, check the hen, and consider all of the other signs around the flock before deciding what needs to change.

Why Is My Chicken Laying Weird Eggs? Wrinkled, Rough, Ridged & Flat-Sided Shells Explained