Botulism (Limberneck) in Laying Hen ...

Botulism (Limberneck) in Laying Hens

Botulism (Limberneck) in Laying Hens

Clinical disease in chickens whose predominant features are flaccid paralysis of legs, wings, neck and eyelids. Limberneck, the original and common name for botulism, precisely describes the paralysis of the neck. Death result from cardiac and respiratory failure. Affected chickens have ruffled feathers, which may fall out with handled. Morbidity (percentage of sick birds) and mortality are related to the amount of acquired toxin. (1, 2, 3)

Paralytic signs progress cranially from the legs to include wings, neck, and eyelids. Initially, affected birds are found sitting and reluctant to move. If coaxed to walk, they appear lame. Wings drop when paralysed. (1, 2, 3)

Observed Clinical Signs Happenings

Visibly sick birds

  • Few  visibly sick birds
  • Limberneck, the original and common name for botulism, precisely describes the paralysis of the neck
  • The birds may drop their head on the floor using the beak as support
  • The birds may lie down with the extended and paralysed neck on the floor
  • Birds appear comatose and may seem dead
  • Affected birds are found sitting and are reluctant to move
  • Birds acting listless, lethargic and depressed
  • A soiled beak, because it rests on litter, is also quite common


  • Low mortality or increases gradually
  • Sudden death
  • Mortality is related to the amount of acquired toxin
  • Mortality up to 8 %  in two weeks period has been observed

Dead Birds

  • Birds are usually in good condition 
  • With low toxin doses, the birds may die in poor body fleshing condition due to paralysis


  • Hens had closed eyes (eyelid  paralysis)


Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Earlobes, abnormalities (except eyes)

  • A soiled beak, because it rests on litter, is also quite common

Body Parts (Neck wings breast abdomen shanks legs hocks feet joints vent skin)

  • Flaccid paralysis of the neck (Limberneck), wings, and legs
  • Wings drop when paralysed


  • Flaccid paralysis of legs, wings, neck and eyelids

Lameness or unusual movement incoordination ataxia

  • If coaxed to walk, they appear lame


  • Ruffled feathers, which may fall out with handling
  • Ruffled hackle feathers
  • Quivering of certain feather tracks has been observed

Botulism (Limberneck) in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  1. Egg drop
  2. Many visibly sick birds
  3. Flock behaviour activity change
  4. Droppings abnormalities
  5. Respiratory abnormalities
  6. Feed Consumption Changes
  7. Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)
  8. Shell quality defects
  9. Internal Egg defects
Causing Agents
Toxic. Caused by a bacterial toxins produced by Clostridium botulinum mainly types A/C.
Affected Systems/Organs
Neurological and Locomotor System. Neck, Wings and Legs.
The toxin is produced in decaying animals (usually carcasses) and plant waist and toxin-containing material (Pond-mod, carcasses, maggots) is consumed by the birds.
Mainly Affects
Removal all dead birds on daily basis. Avoid access to toxin. Many sick birds, if isolated and provided with water and feed, will recover.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Can be dealt with in house
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 881
  2. David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 955
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. 210
  4. Paul McMullin. 2004. A Pocket Guide to Poultry Health and Disease. First Edition.
  5. Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
  6. Donald D. Bell, Williams D. Weaver. 2009.  Commercial Chicken Meat and Egg Production. Fifth Edition.
  7. Gail Damerow 1994. The Chicken Health Handbook.


Raymond W. Sweeney 2016. Outbreak of Type C Botulism in Commercial Layer Chickens. Avian Disease 60(1): 90-94



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