Introduction
Fatty Liver Haemorrhagic Syndrome in poultry is a metabolic disorder that primarily affects older laying hens, especially those kept in cages under high-energy diets. The condition is characterized by an excessively fatty liver, often leading to haemorrhages and sudden mortality due to liver rupture. FLHS is more commonly observed in hot weather and is associated with a drop in egg production, causing significant economic losses in poultry farms.
Causes
FLHS is a nutritional and metabolic disorder influenced by various factors, including:
| Cause | Description |
|---|---|
| High-Energy Diets | Feeding excessively high-energy diets to laying hens, particularly those in cages with restricted movement, leads to fat accumulation in the liver. |
| Nutritional Imbalances | Lack of essential nutrients that aid in fat metabolism (e.g., choline, biotin, vitamin B12) increases the risk of FLHS. |
| High Environmental Temperatures | Hot weather reduces feed intake but increases fat accumulation due to altered metabolism. |
| Choline Deficiency | Choline helps in fat mobilization from the liver; its deficiency results in excessive hepatic fat accumulation. |
| Stress and High Egg Production | Birds undergoing stress (handling, transportation, sudden noise, or fear) or those with high egg production rates are more susceptible to FLHS. |
| Toxins in Feed | Consumption of mouldy feed or mycotoxin-contaminated ingredients can contribute to liver dysfunction and fat accumulation. |
Symptoms
FLHS is often subclinical and remains unnoticed until sudden death occurs. Common symptoms include:
| Symptom | Description |
|---|---|
| Good Physical Condition in Affected Birds | Most affected hens appear healthy and well-fed, with no obvious signs of illness. |
| Sudden Drop in Egg Production | The flock may fail to reach peak egg production or experience a sudden decrease in egg output. |
| Overweight Hens | Birds may exhibit excess body weight (20-25% increase) and enlarged pale combs and wattles. |
| Increased Mortality | Birds are often found dead without prior illness, particularly after stress events (e.g., heat stress, handling, or sudden alarm). Mortality rates range from 2-10%. |
Postmortem Findings
During necropsy, affected birds exhibit the following gross pathological changes:
| Postmortem Finding | Description |
|---|---|
| Presence of Large Blood Clots | Blood clots are found in the abdominal cavity, usually covering the liver, indicating haemorrhage from the liver. |
| Enlarged, Fatty Liver | The liver is significantly enlarged, soft, and friable with a light greyish-brown to yellow colouration. |
| High Liver Fat Content | The liver fat percentage in FLHS cases exceeds 70%, whereas the normal range is 25-50%. |
| Death Due to Liver Rupture | In most cases, death occurs due to massive internal bleeding from a ruptured fatty liver. |
Diagnosis of FLHS
Diagnosis is typically based on:
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Flock History – Sudden mortality in a well-fed laying flock with a recent drop in egg production.
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Postmortem Examination – Presence of fatty, friable liver, abdominal blood clots, and internal haemorrhage.
Laboratory tests are usually not required as gross pathological findings are sufficient for confirmation.
Differential Diagnosis
FLHS can be confused with other conditions. The table below highlights key differences:
| Disease | Key Differences from FLHS |
|---|---|
| Fatty Liver Syndrome (FLS) | No haemorrhages, the liver is enlarged but not ruptured. |
| Aflatoxicosis | The liver shows nodular necrosis, not just fat accumulation. |
| Salmonellosis | The liver appears swollen & congested, with white foci. |
| Newcastle Disease (ND) | Neurological & respiratory signs are present, unlike in FLHS. |
Treatment
Currently, no specific treatment exists for FLHS, but nutritional interventions may help manage the condition:
| Treatment | Effect |
|---|---|
| Vitamin and Nutrient Supplementation | Adding choline chloride, vitamin E, vitamin B12, and inositol to the diet has shown some improvement in affected flocks. |
| Antioxidant Support | Vitamin E and selenium supplementation can help reduce oxidative stress in the liver. |
Prevention and Control
The best way to manage FLHS is through preventive measures:
| Prevention Method | Description |
|---|---|
| Feed Management | Reduce dietary energy levels in high-risk birds. Feed restriction can help prevent excessive fat accumulation. |
| Proper Nutrient Balance | Ensure adequate levels of choline, biotin, vitamin B12, and methionine to promote proper liver function. |
| Avoidance of Mouldy Feed | Prevent feeding mycotoxin-contaminated grains and other toxic feed ingredients. |
| Reduce Stress | Minimize handling, transportation, and sudden environmental changes to reduce stress-induced metabolic disruptions. |
Frequently Asked Questions (FAQs)
Q1: What is the leading cause of FLHS in poultry?
A1: The main cause is excessive fat accumulation in the liver due to high-energy diets, choline deficiency, stress, and high egg production.
Q2: Can FLHS be treated?
A2: There is no specific treatment, but dietary modifications with added choline, vitamin B12, and vitamin E can help manage the condition.
Q3: How can FLHS be prevented?
A3: Prevention involves proper feed management, balanced nutrition, avoiding mouldy feed, and minimizing stress in laying hens.
Q4: What are the postmortem findings in FLHS?
A4: The key postmortem findings include an enlarged, fatty, friable liver, abdominal blood clots, and internal haemorrhage.
Conclusion
Fatty Liver Haemorrhagic Syndrome in poultry is a nutritionally induced disorder that significantly affects laying hens by reducing egg production and causing sudden mortality due to liver rupture. Preventive measures, such as balanced feeding, vitamin supplementation, and stress reduction, are critical to controlling this economically significant disease in poultry farms.
References
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Merck Veterinary Manual
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J.L. Vegad –Poultry Diseases
