Avian gout is a metabolic disorder characterized by abnormal accumulation of uric acid in the bloodstream, leading to the deposition of urates on and within articular surfaces and visceral tissues.
There are two forms of gout in chickens, which are classified based on where urates accumulate.
- Articular gout: Urates accumulate in the synovial capsules and tendon sheaths of the joints. Over time, these deposits can lead to joint damage and bone erosion.
Clinical signs include:- Soft, painful swellings on the feet which progress to pea- or bean-sized raised nodules.
- Lameness or difficulty walking
- Visceral gout (avian urolithiasis): This is the more common and acute form of gout in chickens. It is characterized by the deposition of white, chalky urate crystals on the surfaces of internal organs and within body cavities, including the liver, heart, kidneys, air sacs, intestines, and peritoneum. Visceral gout is often associated with kidney dysfunction or multiple organ failure which can progress rapidly.
Clinical signs include:- Diarrhea, often with white urates adhering to the vent feathers (“pasty vent”)
- Abnormal droppings
- Increased thirst (polydipsia)
- Progressive weight loss
- Reduced appetite
- Depression or lethargy
Causes and Risk Factors
Gout in chickens can result from a variety of dietary, management, infectious, toxic, and genetic factors.
Diet-related factors:- Excess calcium:Feeding high-calcium diets (greater than 1.2%) to non-laying birds—such as chicks, pullets, roosters, or non-laying hens—can lead to kidney damage. This commonly occurs when all flock members are fed layer feed. Poor-quality feed or excessive calcium-rich treats can also contribute.
- Excess protein:Diets exceeding approximately 23% protein can result in increased uric acid production.
- Vitamin deficiencies:: Inadequate levels of vitamin A and vitamin D3 can cause renal damage. Vitamin A deficiency is more likely in chickens without access to fresh greens or pasture.
- Low phosphorus : Phosphorus helps maintain proper pH. Deficiency may increase the risk of kidney stone formation.
- High cholesterol diets: May contribute to kidney dysfunction.
- Purine-rich diets: Feeding meat or high-fructose products can increase uric acid production.
Management-related factors- Dehydration: Limited access to clean water—especially during extreme heat or freezing conditions—can impair kidney function and increase gout risk.
Viral infectionsThese viruses can damage the kidneys and predispose chickens to visceral gout.
Toxins and medications:- Mycotoxins: Eating moldy or improperly stored feed containing mycotoxins can cause kidney damage.
- Aminoglycoside antibiotics:(e.g., gentamicin, amikacin) are known to be nephrotoxic.
- Disinfectants and insecticides: Improper use or overdosing can cause toxicity.
- Sodium bicarbonate: Can disrupt the normal pH balance and increase the risk of kidney stone formation.
- Poisonous plants: Ingestion of plants containing calcinogenic glycosides, such as Cestrum diurnum.
Genetics:
Certain breeds, such as New Hampshire chickens, are predisposed to articular gout due to inherited differences in uric acid handling.
