What Deficiency Causes Curled Toe Paralysis?

December 27, 2025 •

3 min read

Curled toe paralysis is a common sign of a nutritional problem, primarily affecting young chicks. A deficiency in riboflavin, also known as Vitamin B2, is the main cause. This critical deficit impairs nerve function, causing the characteristic curled toes and difficulty walking.

Quick Summary

The nutritional cause of curled toe paralysis in chicks is a lack of riboflavin (Vitamin B2), leading to peripheral nerve degeneration and motor function impairment.

Key Points

Cause: The main cause of curled toe paralysis in poultry is a deficiency in riboflavin (Vitamin B2).
Nerve Damage: Riboflavin deficiency leads to degeneration of the myelin sheaths of peripheral nerves, including the sciatic nerve.
Symptoms: Chicks show leg weakness, walk on their hocks, and the toes curl inward.
Reversibility: Early supplementation with Vitamin B2 can often reverse the condition.
Prevention: A riboflavin-rich diet for both breeder flocks and young chicks is the most effective prevention.

The Importance of Riboflavin for Poultry Health

Riboflavin, or Vitamin B2, is essential for a range of metabolic processes that support cell growth and energy production in poultry. Adequate riboflavin is crucial for a healthy nervous system. A deficiency, particularly in young chicks, results in the degeneration of the myelin sheaths that surround peripheral nerves, especially the sciatic nerve. This nerve damage disrupts signal transmission, which leads to the characteristic inward curling of the toes.

Symptoms and Stages of Curled Toe Paralysis

Curled toe paralysis commonly appears in chicks between 1-2 weeks old when fed a riboflavin-deficient diet. Symptoms develop in stages:

Early Stage: Weakness in the legs, slightly flexed toes, a reluctance to move, and the bird may rest on its hocks. Poor growth and diarrhea are also possible.
Moderate Stage: Increased leg weakness, more noticeable toe curling, and the use of wings to help maintain balance.
Advanced Stage: Toes fully curled, an inability to stand, and a prostrate posture with legs extended. Muscle atrophy may occur. Risk of starvation or being trampled increases.

Treatment and Intervention

Early detection and treatment are critical. Riboflavin supplementation can often reverse early nerve damage. Interventions include:

Use a water-soluble form of riboflavin.
A short course of daily oral riboflavin is effective for young chicks.
A balanced diet is necessary to prevent the condition from returning. Full recovery might not be possible in severe, long-standing cases.

Preventing Curled Toe Paralysis

Preventing curled toe paralysis through proper nutrition is more effective than treating it. Focus on adequate riboflavin at two key stages:

Breeder Flock Diet: Ensure breeding hens receive enough riboflavin (e.g., 10-16 mg/kg feed). This is critical for sufficient riboflavin in eggs and chicks.
Chicks' Starter Feed: Provide fresh starter feed with a guaranteed riboflavin content. Riboflavin is sensitive to light; store feed correctly to maintain its potency.

Other Factors That Can Cause Curled Toes in Poultry

While riboflavin deficiency is the primary cause, other factors can cause similar symptoms:

Management Issues: Leg deformities, such as splay leg, can be caused by improper incubation or slippery brooder floors.
Genetic Factors: Some genetic conditions lead to crooked toes.
Other Deficiencies: Deficiencies in manganese or folate cause leg problems, but not the specific nerve damage seen in riboflavin deficiency.


Feature	Curled Toe Paralysis (Riboflavin Deficiency)	Splay Leg (Management/Genetic)
Cause	Vitamin B2 deficiency, leading to sciatic nerve degeneration.	Improper incubation, slippery floors, or genetic factors.
Onset	Typically appears around 8–14 days post-hatch.	Present at hatch or shortly after.
Physical Signs	Inward curling of toes; chick walks on hocks.	Legs splayed outward; chick unable to stand properly.
Nervous System	Peripheral nerve damage is the primary cause.	No nerve damage; related to muscle/joint development.
Treatment	B2 supplementation, often reversible in early stages.	Taping legs, non-slip flooring. Irreversible if severe.
Prevention	Balanced diet for breeders and chicks; proper feed storage.	Correct incubator settings; non-slip brooding surface.

Conclusion

Curled toe paralysis in young poultry is a sign of riboflavin deficiency, which leads to peripheral nerve degeneration. Prompt Vitamin B2 supplementation can reverse the condition. Preventing this issue through careful nutritional management of both breeder flocks and chicks is essential to minimize losses.

Visit the MSD Veterinary Manual for more information on vitamin deficiencies in poultry.

Frequently Asked Questions

The main cause of curled toe paralysis, especially in young chicks, is a nutritional deficiency of riboflavin, also known as Vitamin B2.

Initial signs include slight leg weakness, reluctance to move, and toes that are mildly flexed. Chicks may also rest on their hocks.

No, they are different conditions. Curled toe paralysis is a nerve issue due to riboflavin deficiency, causing inward-curling toes. Splay leg is a muscle/joint issue, often present at hatch, where legs splay outwards.

Yes, if the deficiency is addressed early, riboflavin supplementation can reverse the nerve damage and cure the paralysis. Long-term damage may be irreversible.

Treatment involves giving a water-soluble form of riboflavin. Many poultry supplements contain Vitamin B2 and can be added to the chick's drinking water.

While Vitamin B2 deficiency can cause health issues in humans, it does not typically lead to curled toe paralysis. Curled toes in humans are usually caused by conditions like neuropathy, arthritis, or ill-fitting footwear.

Prevention requires a well-balanced diet with sufficient riboflavin. Providing both breeder flocks and young chicks with fresh feed containing the correct vitamin levels is key.

Yes, riboflavin is sensitive to light. Improperly stored feed, especially when exposed to ultraviolet (UV) rays or sunlight, can lose its vitamin B2 potency over time.

References

1
Vitamin Deficiencies in Poultry - MSD Veterinary Manual