When Chickens Can’t Walk:

Nutritional Deficiencies and Leg Failure in Poultry

A Resource Guide for Backyard Flock Owners and Small Farm Producers

One of the most distressing things a poultry keeper can witness is a bird that can no longer stand or walk. Leg failure in chickens is not uncommon, and while Marek’s disease and injury are frequently blamed, nutritional deficiencies are among the most treatable and most frequently overlooked causes. This article reviews each major nutritional culprit — what the veterinary and scientific literature tells us, the signs to watch for, and practical steps you can take to address the problem.

Quick Reference: Nutritional Causes of Leg Problems

Deficiency	Most Affected	Key Signs	Treatment
Vitamin B2 (Riboflavin)	Chicks 1–3 wks	Curled toes, hock-walking	B-complex supplement
Vitamin E	Chicks 2–5 wks	Incoordination, tremors, muscle weakness	Vit. E + Selenium supp.
Selenium	Any age	Muscle degeneration, weakness, spread legs	Selenium + Vit. E supp.
Niacin (B3)	Young birds	Bowed legs, enlarged hocks	B-complex, brewer’s yeast
Vitamin D3	Growing birds	Rickets, soft bones, lameness	Vit. D3 supplement, sunlight
Calcium/Phosphorus	Any age	Soft bones, bowing, fractures, paralysis in hens	Feed adjustment, grit
Manganese	Growing birds	Perosis, slipped tendon, joint deformity	Balanced mineral supplement

1. Vitamin B2 (Riboflavin) Deficiency: Curled Toe Paralysis

Riboflavin deficiency is widely recognized as one of the leading nutritional causes of leg problems in chickens. The Merck Veterinary Manual — the definitive veterinary reference for livestock and poultry medicine — notes that changes in the sciatic nerves produce curled-toe paralysis in growing chickens, and that when a diet is missing the full spectrum of vitamins, riboflavin deficiency is typically the first deficiency sign to appear.

Peer-reviewed research from Texas A&M University’s College of Veterinary Medicine (Johnson & Storts, 1988, Veterinary Pathology) documented that chickens fed a riboflavin-deficient diet from hatching showed leg weakness and paralysis as early as 12 days of age. The study found that the sciatic nerves were enlarged, and microscopic examination showed Schwann cell swelling and segmental demyelination — the nerve’s protective coating breaks down, disrupting signals to the legs and feet.

A 2023 study in the journal Toxicology and Industrial Health (Cai et al.) confirmed that riboflavin deficiency produces severe peripheral nerve demyelination in young, rapidly growing chickens, and importantly, that restoring normal riboflavin levels results in rapid remyelination and recovery — meaning early intervention works.

PoultryDVM.com, a clinical resource for poultry veterinarians, notes that riboflavin is one of the vitamins most likely to be deficient in commercial chicken feeds, particularly those using corn or soybean meal as primary ingredients. Riboflavin is also easily destroyed by ultraviolet light, meaning feed stored in sunlight or left outdoors can quickly lose its riboflavin content.

Signs to Watch For

• Toes curling inward or downward (curled-toe paralysis)
• Bird resting or walking on its hocks rather than its feet
• Leg weakness with wings used for balance
• Reluctance to move, slow growth, emaciation
• In advanced cases: bird lies flat with legs extended in opposite directions

Treatment

Supplement with a riboflavin-containing B-complex supplement in the drinking water. Many birds show improvement within one to two weeks if the nerve damage has not become permanent. Younger birds respond better. Review feed storage and freshness.

2. Vitamin E Deficiency: Three Distinct Disorders

Vitamin E is a fat-soluble antioxidant essential for nerve, muscle, and immune function. The Merck Veterinary Manual and Rural Veterinary Outreach both describe three clinically distinct conditions that can arise from vitamin E deficiency, each affecting mobility differently.

Encephalomalacia (“Crazy Chick Disease”)

Softening of brain tissue resulting from oxidative damage. Most common in chicks 2–5 weeks old fed diets high in polyunsaturated fats and low in vitamin E. Signs include head tremors, loss of balance, incoordination, and falling. Birds may be unable to right themselves.

Exudative Diathesis

Damage to capillary walls causing fluid accumulation under the skin, particularly along the abdomen and inner thighs. Affected birds often stand with legs spread wide apart and have difficulty walking. Skin may appear bluish-green in affected areas. This condition results from selenium deficiency in combination with vitamin E deficiency.

Nutritional Muscular Dystrophy (White Muscle Disease)

Progressive degeneration of skeletal, smooth, and cardiac muscle. Affected birds are often unable to stand or walk and are found on the ground with legs spread laterally. Muscle tissue may appear pale or white on post-mortem examination. Rural Veterinary Outreach notes this form can affect all muscle groups, including heart muscle, making it potentially fatal.

Signs to Watch For

• Head tremors, falling, or inability to right itself (encephalomalacia)
• Spread-legged stance, bluish skin discoloration under wings or inner thighs (exudative diathesis)
• Progressive muscle weakness, bird found lying flat with legs spread (muscular dystrophy)
• Most common in chicks 15–30 days old raised in confinement

Treatment

Supplement with vitamin E and selenium together, as the two nutrients work synergistically. Selenium has a narrow margin between therapeutic and toxic doses — do not exceed recommended dosing without veterinary guidance (see Merck Veterinary Manual: Mineral Deficiencies in Poultry).

3. Selenium Deficiency: Muscle Degeneration

Selenium is a trace mineral that works in tandem with vitamin E as an antioxidant system. As the Merck Veterinary Manual notes, selenium deficiency in growing chickens causes exudative diathesis, and many commercial poultry feeds now include added selenium at 0.1–0.3 ppm specifically to prevent nutritional myopathy. Backyard flocks on grain-heavy scratch diets or improperly stored feed are most at risk.

Exposure to metals such as arsenic, zinc, and copper can antagonize selenium absorption, and has been associated with outbreaks of nutritional myopathy even when dietary selenium levels appear adequate.

Signs to Watch For

• Muscle weakness and wasting, particularly in breast and leg muscles
• Birds unable to stand, found on the ground with legs spread
• Ruffled feathers and unthriftiness at 3–6 weeks of age
• Bruising easily; large scabs forming on old bruises

Treatment

Selenium and vitamin E must be supplemented together for best results. The Furry Critter Network veterinary medication guide emphasizes that selenium supplementation can be lifesaving but carries a real risk of toxicity if overdosed. Water-soluble selenium/vitamin E powders are available and convenient, but consult a veterinarian if multiple birds are affected.

4. Niacin (Vitamin B3) Deficiency: Bowed Legs and Hock Swelling

Niacin deficiency primarily produces problems in the skin and digestive tract, but also causes significant leg deformity in poultry. According to the Merck Veterinary Manual, niacin deficiency in chickens produces enlargement of the tibiotarsal joint, bowing of the legs, poor feathering, and dermatitis. In young chicks, the tongue and oral cavity may become inflamed — a sign known as “black tongue.”

While chickens are less severely affected than ducks and turkeys, niacin deficiency in chickens is still clinically significant. Corn-heavy diets with no vitamin supplementation are a primary risk factor, as corn provides minimal usable niacin. The Merck Veterinary Manual notes that an allowance of at least 30 mg/kg of feed is needed for chickens, with many nutritionists recommending two to two-and-a-half times that amount.

Signs to Watch For

• Bowed or splayed legs, enlarged hock joints
• General weakness, reluctance to walk
• Poor feathering, slow growth
• Inflamed mouth or tongue (“black tongue”) in young chicks

Treatment

Supplement with a B-complex vitamin in the drinking water, or add brewer’s yeast to feed (a natural niacin source). Use plain niacin (nicotinic acid) and avoid no-flush or slow-release forms, which are not well utilized by birds. Niacin toxicity is possible at excessive doses, so follow label instructions carefully.

5. Vitamin D3 Deficiency: Rickets and Soft Bones

Vitamin D3 is essential for calcium and phosphorus absorption and bone mineralization. Without it, bones remain soft and unable to bear the bird’s weight. The Merck Veterinary Manual states that a deficiency can result in rickets in young growing chickens or osteoporosis in laying hens, even when dietary calcium and phosphorus levels appear adequate.

According to Dr. Jacquie Jacob of the University of Kentucky’s poultry extension program, rickets in poultry is primarily a nutritional problem resulting from a vitamin D3 deficiency or calcium/phosphorus imbalance. Birds raised entirely indoors without access to sunlight are particularly vulnerable, as UV light from the sun is a natural source of vitamin D synthesis.

The Poultry Site’s disease guide notes that the Achilles tendon and hock joints are frequently involved, and that the condition is seen worldwide in chickens, turkeys, and ducks.

Signs to Watch For

• Lameness, reluctance to move, birds found squatting
• Soft, rubbery, or easily fractured bones and beak
• Enlarged hock joints
• Poor growth and weight gain
• In laying hens: drop in egg production, thin-shelled or soft eggs

Treatment

Correct the diet with vitamin D3 supplementation. The Poultry Site recommends correcting at three times the standard vitamin D dose for approximately two weeks, then returning to maintenance levels. Ensure birds have access to natural sunlight when possible. Evaluate calcium and phosphorus ratios in the feed alongside vitamin D.

6. Calcium and Phosphorus Imbalance

Calcium and phosphorus must be present in the correct ratio for bones to develop properly. The Merck Veterinary Manual’s entry on noninfectious skeletal disorders in poultry notes that imbalances can result from inadequate nutrition, intestinal disease with malabsorption, or the use of feeds formulated for the wrong life stage — for example, feeding layer rations to young chicks, or broiler feed to laying hens.

Subclinical rickets from calcium/phosphorus imbalance is fairly common and often associated with poor overall performance in broiler flocks, even when no obvious lameness is present. In laying hens, calcium deficiency has a unique and dramatic effect: hens with insufficient calcium, phosphorus, or vitamin D3 may be found suddenly paralyzed or dead while in the process of forming an eggshell (Merck Veterinary Manual: Calcium Metabolism Problems in Hens).

Signs to Watch For

• Bowed or soft leg bones, spontaneous fractures
• Birds going off their legs, resting in a squatting position
• Soft or thin-shelled eggs, reduced egg production in hens
• Swollen hocks and poor growth in young birds

Treatment

Feed the age-appropriate ration for your birds. Ensure laying hens have access to supplemental calcium (oyster shell offered free-choice). Review grit access and feed freshness. Supplement with vitamin D3 as needed, and consult a poultry veterinarian if multiple birds are affected simultaneously.

7. Manganese Deficiency: Perosis and Slipped Tendon

Manganese deficiency is a specific and serious cause of leg deformity in chickens and turkeys. The Merck Veterinary Manual describes the classic presentation as perosis: enlargement and malformation of the tibiometatarsal joint, twisting and bending of the lower leg bones, thickening and shortening of the leg bones, and in severe cases, slippage of the gastrocnemius (Achilles) tendon from its condyles. Once the tendon slips, the condition is usually permanent.

High levels of calcium and phosphorus in the diet can actually worsen manganese deficiency by reducing its absorption in the intestinal tract. This means birds on high-calcium feeds, or those receiving excessive calcium supplementation, may be at elevated risk for manganese deficiency even if manganese is present in the diet.

Signs to Watch For

• Enlargement or deformity of the tibiometatarsal (hock) joint
• Twisting or bowing of the lower leg
• Shortened, thickened leg bones
• Slipped Achilles tendon — bird walks on the side or back of the leg (usually irreversible)

Treatment

Correct the diet with a balanced mineral supplement containing manganese. Reduce excess calcium if supplementation has been excessive. Slipped tendons that have been present for more than a short time are typically permanent, so early identification is critical. Prevention through a properly balanced commercial ration is the best approach.

What To Do: Step-by-Step Response

1. Isolate the affected bird. A bird that cannot walk is vulnerable to bullying, trampling, and feed competition. Separate it immediately and place food and water within easy reach.
2. Evaluate your feed. Check that the feed is age-appropriate, within its use-by date, stored in a cool dry location out of sunlight, and not contaminated with mold. Vitamins in feed degrade within approximately two months of milling.
3. Begin broad-spectrum supplementation. If the specific deficiency is unclear, a broad-spectrum vitamin supplement added to the drinking water is a reasonable first response. Look for products containing B-complex vitamins (including riboflavin and niacin), vitamins A, D3, and E, and selenium.
4. Monitor for response. Nutritional deficiencies that have not caused permanent damage often respond within days to two weeks. Lack of improvement — or worsening — warrants a veterinary exam.
5. Consult a poultry veterinarian. If multiple birds are affected at once, if the bird is not improving, or if the cause is unclear, get a professional evaluation. A vet can rule out Marek’s disease, bacterial joint infections, and other non-nutritional causes.

Where to Find Vitamin Supplements for Chickens

Poultry vitamin supplements are widely available at farm supply stores and online. Below are commonly recommended products:

• Rooster Booster Liquid B-12 Plus Vitamin K — Concentrated liquid B-12 added to water or feed. Available at Tractor Supply Co. and Amazon.
• Rooster Booster Vitamins & Electrolytes with Lactobacillus — Broad-spectrum soluble powder containing riboflavin, B-1, B-6, vitamins A, D3, and E. Available at Tractor Supply Co.
• Rooster Booster Poultry Cell — Liquid formula with essential B-vitamins, vitamins A, D, and E, and bio-available iron. Highly rated for recovery support. Available at Tractor Supply Co.
• Nutri-Drench Poultry Supplement — Fast-absorbing molasses-based liquid that enters the bloodstream quickly. Useful for birds too weak to eat well. Available at Tractor Supply Co. and online.
• Sav-A-Chick Vitamin & Electrolyte Supplement — Soluble powder supplement popular for young chicks. Widely available at farm stores and online.

For birds showing active symptoms, many experienced flock keepers administer a supplement via oral syringe once daily until improvement is seen, then transition to adding the supplement to the flock’s drinking water for the rest of the flock.

 

References and Resources

• Johnson WD, Storts RW. (1988). Peripheral neuropathy associated with dietary riboflavin deficiency in the chicken. Veterinary Pathology, 25(1), 9–16. https://doi.org/10.1177/030098588802500102
• Cai Z, et al. (2023). Avian riboflavin deficiency causes reliably reproducible peripheral nerve demyelination and rapid remyelination. Toxicology and Industrial Health. https://doi.org/10.1177/09603271231188970
• Shastak Y, Pelletier W. (2023). From Metabolism to Vitality: Uncovering Riboflavin’s Importance in Poultry Nutrition. Animals (Basel), 13(22), 3554. PMID: 38003171
• Merck Veterinary Manual. (2024). Vitamin Deficiencies in Poultry. com/poultry/nutrition-and-management-poultry/vitamin-deficiencies-in-poultry
• Merck Veterinary Manual. (2024). Mineral Deficiencies in Poultry. com/poultry/nutrition-and-management-poultry/mineral-deficiencies-in-poultry
• Merck Veterinary Manual. (2024). Nutritional Myopathy in Poultry. com/poultry/myopathies-in-poultry/nutritional-myopathy-in-poultry
• Merck Veterinary Manual. (2024). Noninfectious Skeletal Disorders in Poultry. com/poultry/disorders-of-the-skeletal-system-in-poultry/noninfectious-skeletal-disorders-in-poultry
• Merck Veterinary Manual. (2024). Calcium Metabolism Problems in Hens. com/poultry/disorders-of-the-reproductive-system-in-poultry/calcium-metabolism-problems-in-hens
• Jacob J. (2017). Rickets in Poultry. University of Kentucky Cooperative Extension / poultry.extension.org
• com. Curly Toe Paralysis in Chickens. poultrydvm.com/condition/curly-toed-paralysis
• com. Vitamin E Deficiency in Chickens. poultrydvm.com/condition/vitamin-e-deficiency-in-chickens
• com. Selenium Deficiency in Chickens. poultrydvm.com/condition/selenium-deficiency
• Rural Veterinary Outreach. (2022). Vitamin E and Selenium Deficiency. org
• The Poultry Site. Rickets (Hypocalcaemic). com/disease-guide/rickets-hypocalcaemic