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Finding an abnormal egg in the nesting box is always a mystery. What causes them and why does it happen? Can you still eat the abnormal egg or should you throw it away? Does your hen need medical treatment if she is laying abnormal eggs?

When trying to understand the causes of abnormal eggs and egg laying problems, it can be helpful to first understand how an egg is formed.

How an Egg Is Formed

Did you know that an egg only has about 75 calories, but provides 7 grams of protein, plus vitamins A, D, B12, riboflavin, pantothenic acid, phosphorus, choline, and carotenoids? Talk about a nutritional powerhouse!

It takes a hen about 25 hours to form an egg. First, the egg’s yolk is formed in the hen’s ovary. Unlike most mammals, hens only have one functioning ovary on the left side. A laying hen usually has many active yolks in her ovary at any given time, all in different stages of the developmental process.

The yolk matures in about 10 days. When the yolk is mature it is released from the ovary into the funnel (infundibulum). If you have a rooster whose been doing his job, this is where the egg will be fertilized. The entire process of fertilization takes about 15 minutes. The egg then moves on to the magnum.

In the magnum, the inner and outer shell membranes are formed, as well as mineral salts and water. This process will take around three hours. Now it is time for the egg to move into the isthmus.

The egg white (albumen) is secreted and layered around the yolk in the isthmus. After about an hour, the partially formed egg will move into the uterus, where it receives its shell. It takes about 21 hours for the shell to completely form.

When this entire process is complete, the egg passes through the vagina and is laid by the hen. It takes about 1 minute for the egg to pass from the uterus through the vagina.

Causes of Abnormal Eggs and Egg Laying Problems in Backyard Hens

As you can see, this is a complicated process, and there’s a lot of opportunity for problems to arise. There’s a good chance that you will find an abnormal egg in your henhouse at some point, or have a hen who has some sort of egg laying problem. Let’s look at some of the common causes of abnormal eggs and egg laying problems in backyard hens.

Soft Shelled or No Shell Eggs

This is generally caused by a malfunction in the uterus. It is a common issue for pullets whose reproductive equipment is still immature, and in older hens. Sometimes, it can even be a genetic defect.

Poor nutrition can also be the reason behind soft shelled eggs. Make sure to feed a balanced layer ration with the right amounts of calcium and vitamin E, B12 and D, and the minerals phosphorus and selenium.

Hens with this issue will not only lay soft shelled eggs, but can sometimes go without laying any eggs at all for a while, to surprising you with a perfect egg. Although the hen is healthy, a hen with this problem has a greater risk of contracting egg yolk peritonitis.

Egg Yolk Peritonitis

Egg yolk peritonitis occurs when fluid leaks from the oviduct, into the abdominal cavity, and causes an infection. E. coli bacteria will then grow very quickly in the abdomen, and the hen’s condition will decline rapidly. The vet may prescribe antibiotics and anti-inflammatory medication, but unfortunately, the hen will often die before you even notice she is sick.

Egg Binding

When a hen lays an egg, the egg passes into the vagina and turns so that it is laid blunt end first. If the egg is very large, it could get stuck, which causes the hen to become egg bound.

Egg bound hens can quickly become very ill, and they will require some assistance with removing the egg. Try giving the hen a warm water bath, massaging the abdomen very gently, and lubricating the vent with some petroleum jelly to help the hen pass the egg.

Blood on The Egg Shell

Sometimes you will find an egg that has anywhere from a few spots to an alarming amount of blood on the egg shell. This is usually caused by the rupture of small blood vessels in the hen’s vagina when she is straining to lay her egg. The problem is common in young pullets and hens who are overweight.

Odd Shaped Eggs

Occasionally, you may find an egg that is very large, very small or has an odd shape, but is otherwise normal. This can be common in young pullets with an immature shell gland and they will eventually grow out of it.

However, there can be other causes that will need to be addressed immediately, such as a disease like infectious bronchitis. Stress and overcrowding could also be the cause. Be watchful for symptoms of illness, and make sure your hens have plenty of space. Be aware of issues that might be causing stress, such as bullying by a dominant hen.

Egg Shell Abnormalities

Eggs will sometimes have shells that have abnormalities like pale color, wrinkles in the shell, or calcium deposits. This can happen when a hen has defective shell glands, a disease such as infectious bronchitis, or is stressed or disturbed during the calcification process. Issues in the hen’s diet, such as excessive calcium or copper deficiency, could also be the cause.

Eggs with No Yolk (aka Fairy Eggs)

Tiny eggs with no yolk are often called fairy eggs. A young pullet may lay a fairy egg or two when she first starts laying. Sometimes, the cause can be a disturbance in the hen’s reproductive cycle. The hen’s oviduct may have released a piece of reproductive tissue or some other small foreign mass may have entered the oviduct. The foreign object is treated like a normal yolk and the reproductive system forms the membranes, white, and shell around it.

Blood Spots on the Egg Yolk

Sometimes, when the egg yolk is maturing in the hen’s ovary or when the mature yolk is released, a small blood vessel may rupture in the ovary. The blood that is released will then end up being encased in the shell, along with the yolk and other egg contents.

Environmental issues such as stress or overcrowding are a common cause. Nutritional problems, such as incorrect levels of vitamins A and K, could also be the problem. Feeding stale, wet, or moldy feed should also be avoided.

Double or Multi Yolk Eggs

Can you believe that as many as 9 yolks have been found inside a single egg? Multi yolk eggs most commonly occur in young pullets when they are just starting to lay. The problem occurs when more than one yolk matures and gets released at the same time.

Lash Eggs (Salpingitis)

A lash egg consists mostly of coagulated puss without and yolk or egg white. They are the result of an infection that causes inflammation in the hen’s oviduct, called Salpingitis. The hen’s immune system tries to fight off the infection and a waxy, cheese-like pus is formed. There may or may not be a yolk, white, membranes or a shell along with the pus, but usually it is mostly just a yellowish, cheesy, pus ball. GROSS!

In addition to laying lash eggs, hens with Salpingitis may frequently lay soft-shelled eggs, be lethargic, lose weight, and have labored breathing and abdominal swelling. The hen may also adopt an upright, penguin-like stance.

Unfortunately, salpingitis often results in the death of the hen. The infection has usually been present of months before it is diagnosed, and most hens will not survive even 6 months with Salpingitis. Survivors of the infection will most likely never lay normally again.

Vent picking, respiratory infections and obesity put a hen at greater risk of contracting this infection. It also more common in hens over 2 years old.

Antibiotics and/or surgery are the only successful treatments, but the prognosis is not very hopeful.


Most egg laying problems and abnormalities are not serious and they can be prevented or resolved by feeding a proper diet, avoiding stress and overcrowding, and keeping a clean coop. In general, eggs with minor abnormalities are safe to eat, unless disease is the cause of the abnormality.


The Chicken Health Handbook; by Gail Damerow

Salpingitis & Lash Eggs in Backyard Chickens;The Chicken Chick;

10 Abnormal Chicken Eggs & What You Need To Know!; The Pampered Chicken Mama;

Troubleshooting Common Egg Problems; Quarto Knows Blog;

Common Egg Quality Problems; Backyard Chickens Blog;

Egg & Laying Issues; The Chicken Vet;

How Chickens Lay Eggs and 3 Common Laying Problems; The Happy Chicken Coop;

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