Fatty Liver Syndrome in Chickens: Causes, Signs and Prevention

Fatty liver disease is an important condition in laying hens, particularly in backyard chickens that are overweight or receiving an energy-rich diet.

Laying hens naturally carry more fat within the liver than non-laying birds because the liver plays a major role in producing the fats required for egg yolk formation. Problems develop when excessive fat accumulates within the liver, making it enlarged, fragile and more susceptible to haemorrhage.

In laying hens, this condition is commonly referred to as fatty liver haemorrhagic syndrome (FLHS).

What Causes Fatty Liver Syndrome?

FLHS develops when the amount of energy a hen consumes exceeds what she uses for maintenance, activity and egg production.

Several factors can contribute, including:

• Excessive energy intake
• Obesity
• Large amounts of table scraps and treats
• Poorly balanced diets
• Limited exercise
• Confinement and lack of opportunities to forage
• High levels of egg production

Backyard chickens kept as pets can be particularly vulnerable when they receive a complete layer feed as well as generous amounts of treats, scraps and energy-dense foods.

What Are the Signs?

Fatty liver disease can be difficult to recognise before it becomes severe.

Affected hens are often overweight, with excessive fat deposited around the abdomen and internal organs.

Signs may include:

• Obesity or excessive body condition
• Reduced activity
• Pale comb and wattles
• Reduced or sudden changes in egg production
• Weakness or lethargy
• Abdominal enlargement
• Sudden collapse or death

Unfortunately, some hens show very few warning signs before a liver haemorrhage occurs.

Why Can Fatty Liver Be Fatal?

As excessive fat accumulates, the liver becomes enlarged and increasingly fragile.

The liver can rupture, resulting in significant internal bleeding into the abdominal cavity. In severe cases, this can cause sudden death.

A badly affected liver may be vulnerable to haemorrhage following relatively minor physical stress or trauma.

Post-mortem examination typically reveals a pale, enlarged, fatty and fragile liver, often accompanied by large amounts of abdominal fat and internal haemorrhage.

Obesity and Reproductive Problems

Excessive abdominal fat doesn't just affect the liver.

Obesity can interfere with normal reproductive function and is associated with a range of problems in laying hens.

Overweight hens may be at greater risk of reproductive complications, including difficulty laying and cloacal prolapse.

Maintaining a healthy body condition is therefore important for much more than preventing fatty liver disease.

How Do You Know if Your Chicken Is Overweight?

Feathers can make body condition surprisingly difficult to judge by appearance alone.

Get into the habit of physically assessing your chickens.

Feel the breast muscles on either side of the keel bone and assess the amount of fat around the abdomen. Regular weighing can also be useful, particularly if you know the normal weight range for the breed.

A chicken can look perfectly normal beneath its feathers while carrying a substantial amount of internal fat.

Preventing Fatty Liver Syndrome

Start With a Complete Diet

A nutritionally complete poultry feed should make up the majority of the diet.

Treats and table scraps should be kept limited. Adding large amounts of high-energy foods to an already complete diet can significantly increase overall calorie intake while diluting the nutritional balance of the feed.

Encourage Exercise and Foraging

Chickens should have opportunities to walk, scratch, forage and explore.

Spreading appropriate feed through a foraging area, providing enrichment and creating an environment that encourages movement can help increase activity.

Monitor Body Condition

Don't wait until a hen is obviously obese.

Regular body condition assessment allows you to identify excessive weight gain early and adjust management before it develops into a more serious health problem.

What About Treatment?

Management primarily involves correcting the factors contributing to excessive fat accumulation.

This may include:

• Removing unnecessary high-energy treats and scraps
• Providing an appropriately formulated complete diet
• Encouraging gradual increases in activity
• Monitoring body weight and condition
• Investigating other factors contributing to liver disease

Weight reduction should be gradual and nutritionally balanced. Severely restricting feed is not an appropriate way to manage an overweight laying hen.

Birds showing weakness, collapse, significant abdominal enlargement or other signs of illness should be assessed by a veterinarian, as fatty liver is only one of several conditions that can produce these signs.

The Takeaway

Fatty liver haemorrhagic syndrome is often a consequence of an imbalance between energy intake, egg production and physical activity.

Backyard hens receiving lots of treats while doing relatively little exercise can be particularly vulnerable.

The good news is that many of the risk factors are manageable. A balanced diet, limited treats, regular exercise and routine body condition monitoring can go a long way towards keeping laying hens at a healthy weight and reducing their risk of fatty liver disease.

Written by Dr Sam Hurley, BSc, BVSc, MAHM