Prolapsed Vent in Laying Hens: Why Diet Matters More Than Most People Realize

Donna Weekes
4 days ago
4 min read

A prolapsed vent is one of the most alarming conditions a chicken keeper can face. It appears suddenly, looks dramatic, and often leads people to believe it was unavoidable or simply “bad luck.”

In reality, a prolapsed vent is rarely random.

In backyard flocks, it is most often the result of long-term nutritional imbalance, even when the foods being offered are considered “healthy.”

Understanding why this happens is key to prevention.

What Is a Prolapsed Vent?

A prolapsed vent occurs when part of a hen’s reproductive tract (usually the uterus or cloaca) protrudes outside the body through the vent after laying or attempting to lay an egg.

During normal egg laying:

The vent briefly everts
The egg is laid
The tissues retract immediately

With a prolapse, those tissues fail to retract and remain exposed.

This is not normal, and it is not harmless.

Why a Prolapse Is a Serious Emergency

Once tissue is exposed:

It dries out quickly
Swelling increases
Other chickens are attracted to the red tissue and begin pecking
Infection, hemorrhage, and cannibalism can follow rapidly

Even when a prolapse is successfully reduced, recurrence is common if the underlying cause is not corrected.

The Most Misunderstood Cause: Diet

Many people assume prolapse is caused by:

A single large egg
A one-time strain
Bad genetics

While those factors can contribute, diet is the most common root cause in backyard hens.

And the problem is not just “junk food.”

How Diet Leads to Prolapse (Step by Step)

1. Too Many Extras = Excess Calories

Backyard hens are often fed:

Scratch grains
Kitchen scraps
Fruits and vegetables
Mealworms
Seeds (Sunflower)
“Healthy” natural foods

Even when each item seems harmless, the combined calorie load adds up quickly.

Layer feed is already nutritionally complete. Anything added on top of it is excess.

2. You Often Cannot See Obesity in Hens

Unlike mammals, the first place excess fat accumulates in hens is around the liver, not under the skin. This condition is known as Fatty Liver Disease (Fatty Liver Hemorrhagic Syndrome).

A hen can appear:

Normal in size
Active and alert
A good layer

While internally, fat is accumulating around vital organs.

By the time fat becomes visible externally, significant internal damage has already occurred.

3. Fatty Liver Disease Increases Prolapse Risk

As fat builds up around the liver and abdominal organs:

Internal space is reduced
Pressure inside the body cavity increases
The oviduct has less room to function properly

This increased pressure makes egg laying more difficult and forces the hen to strain harder, pushing reproductive tissues outward.

At the same time, fatty infiltration interferes with normal muscle function, especially the smooth muscles responsible for laying and retraction.

4. Nutritional Imbalance Weakens Smooth Muscle Function

The muscles involved in laying eggs are smooth muscles, not skeletal muscles.

They depend on:

Proper calcium balance (not just calcium intake)
Adequate vitamin D3 for absorption
Electrolyte balance
Consistent hydration

High-calorie, unbalanced diets disrupt this system.

Weak smooth muscle tone leads to:

Poor egg movement
Increased straining
Failure of the vent and reproductive tissues to retract after laying

5. Oversized or Frequent Eggs Stretch the Vent

Excess energy and protein stimulate:

Larger eggs
More frequent laying

This overstretches the vent and reproductive tissues, reducing their elasticity.

Over time, these tissues lose the ability to return to their normal position — much like an overstretched elastic band.

6. Straining + Pressure = Prolapse

When a hen strains repeatedly against:

Internal fat from Fatty Liver Disease
Oversized or frequent eggs
Weak smooth muscle tone

The reproductive tissue is forced outward and cannot pull itself back in.

That is a prolapse.

Why “Healthy Foods” Can Still Cause Harm

This is one of the hardest concepts for people to accept.

Foods such as:

Fruits
Vegetables
Seeds
Mealworms
Grains
Herbs

Are not harmful on their own.

But chickens are not humans.

They require:

Precise calcium-to-phosphorus ratios
Controlled energy intake
Consistent nutrient density

Even nutritious foods dilute the balance of a complete layer ration when fed too often or in excess.

The issue is not toxicity — it is imbalance.

Prevention: What Actually Works

Feed a Balanced Layer Ration (90% of the Diet)

This should be the primary food source
Designed to meet calcium, protein, and energy needs

Offer Oyster Shell as a Side Dish

Do not mix it into their feed
Each hen has her own calcium requirement and can regulate her own intake
Oyster shell provides extra calcium needed for strong bones and proper muscle contraction during egg laying
Hens instinctively know when they need it

Limit Treats Severely

Treats should be occasional, not daily
Scratch and grains should eliminated as there is no nutritional benefit and is equal to feeding your kids candy

Watch Body Condition — Not Just Appearance

A hen can be obese internally without looking fat
Soft abdominal padding and reduced stamina are warning signs

A Hard but Honest Reality

Despite best efforts, not every prolapse can be resolved.

Repeated prolapse causes:

Chronic pain
Ongoing risk of injury
Poor quality of life

In some cases, humane euthanasia is the kindest option.

This is not failure — it is responsible animal care.

Final Thoughts

Most backyard keepers cause prolapse without realizing it, simply by trying to spoil their chickens.

Food is love — but for laying hens, balance is health.

A well-fed hen is not the one with the most variety, but the one whose nutritional needs are met consistently and correctly.

Prevention starts in the feed dish — and giving oyster shell on the side ensures your hens have the calcium they need without upsetting the balance of their complete diet.