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Avian Osteoporosis

Cage Layer Fatigue, Brittle Bone Disease

Avian osteoporosis is a common bone disease in laying hens which increases their risk for bone fractures. It is a severe welfare concern in commercial laying hens, especially those that are kept confined in tiny cages their entire lives. In the United Kingdom, recent studies showed that 29% of laying hens had at least one broken bone.

Osteoporosis, named after the latin equivalent for "porous bones", which results in decreased bone strength and density. This causes the bones to weaken. Once they are weakened, it doesn't take much for them to break---even jumping down from a roosting perch could potentially break the leg of a hen with osteoporosis.

The reason hens are particularly susceptible to osteoporosis is related to egg laying---thus hens with "high egg production" rates are thus more prone to this disease. Every time a hen lays an egg, it depletes her body (including bones) of important minerals, with one of the most significant being calcium. Bone mineral loss begins when hens reach sexual maturity, and continues throughout their life span as long as they lay eggs. The increased egg laying demands on modern hens, requires a proportional increase in the amount of calcium in the diet. This is because the major component of eggshells is calcium carbonate. Calcium is important for the formation of the egg shell as well as the quality and thickness of the shell. If hens are not provided enough calcium to meet the high demands required for egg laying, the calcium is taken from their bones. The condition can be made worse by metabolic deficiencies related other nutrients as well---such as inadequate or unbalanced quantities of phosphorus or vitamin D in the diet.

Symptoms

Lameness
Reluctance to move
Fragile bones that easily fracture
Paralysis

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Radiographs

Treatment

MethodDetails
Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food.
Additional calcium and vitamin D
Omega 3 fatty acids

Prevention

  • Ensure laying hens receive a balanced diet with extra calcium. Feeding calcium in particulates, either as oyster shell or limestone granules, may extend the period of calcium absorption during the night, which reduces the depletion of medullary bone and benefits the eggshell quality
  • Allow hens plenty of exercise
  • Oral supplementation with 20 mg/kg of ipriflavone in feed
  • Provide supplemental Omega 3 Fatty Acids in diet- Studies showed a significant 40 to 60% reduction in keel bone breakage rate, and a corresponding reduction in breakage severity.

Prognosis

Scientific References

Age Range

It is most common in adult laying hens kept in cages.

Risk Factors

  • Light-hybrid laying hen breeds with small skeletal frames
  • Lack of exercise
  • Insufficient calcium levels in feed
  • Hens producing eggs at a high rate
  • Poor diet, including malnutrition
  • Weight loss
  • Liver disease
  • Chronic kidney disease
  • Cancer
  • Steroids (glucocorticoids)