What it looks like
Tremors or trembling — Head and neck shake rapidly and uncontrollably; bird appears to vibrate or shiver; tremors worsen with stress
Incoordination and ataxia — Bird staggers, stumbles, or falls; cannot walk straight; legs appear weak and uncontrolled
Sitting on hocks — Bird spends excessive time sitting on hocks (squatting with legs folded); stands briefly then collapses
Paralysis — Legs become completely paralyzed; bird cannot stand or walk; may be unable to eat or drink
Dull or glazed eyes — Eyes appear less alert, less bright than healthy chicks; may appear unaware of surroundings
Prostration or depression — Chick is severely depressed, lies on side frequently, unresponsive to stimulation
Poor feed and water intake — Affected chicks struggle to reach feeders and waterers due to incoordination; may starve or dehydrate
Likely causes
What to do
No cure or treatment for avian encephalomyelitis. Management is supportive: provide soft, easy-to-reach feed and water to prevent starvation. Isolate severely affected chicks to reduce stress. Most affected birds do not recover; euthanasia is often the most humane option. Birds that recover may remain permanently neurologically impaired.
When to see a vet
See a vet if your bird shows severe signs or doesn’t improve within a few days of treatment.
Prevention
Breeder flock vaccination is the most effective prevention. Purchase chicks from hatcheries with vaccinated breeding flocks. Maintain strict biosecurity to prevent virus introduction. Ensure good hygiene and sanitation in brooder houses. Source chicks only from reputable hatcheries with disease-free flocks.
FAQ
Is avian encephalomyelitis contagious?
Yes. The virus spreads from infected hens to chicks before hatching. It can also spread through contaminated equipment or flock contact. Isolate affected chicks and clean equipment thoroughly to prevent spread.
Can recovered chicks go back to the flock?
Recovered chicks may carry the virus and spread it to other birds. Additionally, permanent neurological damage may prevent them from thriving. Most keepers cull severely affected birds. Consult your vet about specific birds.
How do I prevent avian encephalomyelitis?
Source chicks from hatcheries with vaccinated breeder flocks. Maintain biosecurity and strict sanitation. Avoid mixing chicks from unknown or unvaccinated sources. Vaccination of your own breeder flock is the gold standard for prevention.
What is the difference between avian encephalomyelitis and other neurological problems?
AE tremors are rapid and persistent, starting early in chick life. Other causes (vitamin deficiency, Marek’s disease) have different symptom patterns and timelines. Your vet can test to confirm the cause and guide treatment.
If I buy from a vaccinated flock, am I protected?
Purchasing from vaccinated hatcheries significantly reduces risk but doesn’t guarantee immunity. Some vaccinated breeder birds may still shed virus. Maintain ongoing biosecurity and monitor new chicks closely for early signs.
For more help, try our chicken symptom checker or read about signs your chicken is sick.