Gout

Gout is an inflammatory disease caused by the accumulation of urate crystals in the joints or throughout one or more organs in the duck's body. Urate deposition occurs as a result of impaired kidney function, impaired excretion of uric acid, and/or by overloading the kidneys with too much uric acid for the kidneys to handle. There are two forms of gout that differ depending on the location of the deposition of uric acid within the duck's body.

• Articular gout: Articular gout is the accumulation of sodium urate crystals in the joints and synovial sheaths. Once deposits begin to develop at a particular location, they will continue to grow over time and form tophi (an accumulation of urate crystals).
• Visceral gout: Visceral gout occurs as a result of the accumulation of sodium urate crystals within one or more organs, such as the kidneys, liver, heart, pericardium, and air sacs.

In some ducks, visceral gout and articular gout may occur at the same time.

Articular Gout versus Visceral Gout Comparison

	VISCERAL GOUT	ARTICULAR GOUT
Typical Onset:	Acute	Chronic
Prevalence:	Common	Sporadic
Gender:	Both	Mostly male ducks
Percent of flock affected:	Can be up to 100% of the flock	Individual birds
Gross lesions observed in organs after death
Kidneys:	Almost always involved. Abnormally sized and covered w/ white chalky deposits	May become involved. Usually appears normal unless the bird was dehydrated.
Joints:	May or may not be involved	Always, especially the feet
Possible causes:	Dehydration Sodium bicarbonate Infectious agents Vitamin A deficiency Secondary to urolithiasis Neoplasia Immune mediated glomerulonephritis Exposure to toxic substances	High protein diet Excess dietary calcium in diet Low-phosphorus diet High energy diet Genetic defect Mycotoxins

Gout Causes
Gout can occur as a result of a number of different factors, with the most common being diet, dehydration, viral infections, and exposure to nephrotoxic drugs or toxins.

Diet-related factors:

• Excess dietary calcium: Feeding non-laying ducks (such as ducklings, drakes, and older ducks that don't lay eggs anymore) a high calcium diet for an extended period of time can cause kidney damage. This is most commonly related to feeding all flock members commercial laying hen feed. It can also be caused by a feed mill error, feeding an abundance of table scraps or treats that contain high amounts of calcium, and by providing low-quality poultry feed that contains large particles of calcium carbonate (CaCO3).
• Vitamin A deficiency: Vitamin A is an essential vitamin for ducks, and if they are receiving a vitamin A-deficient diet for any length of time, it can cause damage to the lining of the ureters (the ducts by which urine passes from the kidneys to the cloaca), leading to gout. Not all commercial poultry feeds contain vitamin A, and in those that do, the amount degrades over time, especially when it is exposed to sunlight. This is because vitamin A is very sensitive to sunlight. Ducks that do not have regular access to pasture grass are at a high risk of vitamin A deficiency, as grasses and various weeds (such as dandelion) are a good source.
• Low-Phosphorus diet: Ducks receiving a diet low in phosphorus are more at risk of developing gout, as phosphorus acts as a urine acidifier which helps in the prevention of kidney stones.
• High cholesterol diet: Ducks fed a diet high in cholesterol are more prone to developing renal disease.

Management-related

• Dehydration: If ducks become dehydrated, this puts them at risk of kidney damage. Dehydration is usually caused by lack of water, which most often is a risk during hot weather with increased water intake or during cold weather from lack of water access due to the formation of ice along the surface of the water source.
• Mycotoxins: Mycotoxins are toxins produced by molds that are commonly found in commercial poultry feeds worldwide, in addition to bedding materials, and other feedstuff. Ingestion of certain types of mycotoxins are known to cause kidney damage.
• Sulfa and Aminnoglycoside Antibiotics: These types of antibiotics are eliminated from the body through the kidneys, and are known for causing kidney damage to birds, particularly when ducks are not drinking enough water.
• Disinfectants and Insecticides: Are safe and effective when used properly in accordance to manufacturer recommendations, however they can cause kidney damage when the dosage is miscalculated.
• Sodium bicarbonate (baking soda): Giving ducks sodium bicarbonate can contribute to the onset of gout by disrupting the pH of the urine, making it more alkaline, and putting duck more at risk of kidney stones.