What is Gout?
Renal disease is a common cause of gout in various species of birds. In a healthy bird, urates are excreted with mucus through the urine. Dysfunction in the renal system can decrease this process, resulting in excessive amounts of uric acid left in the blood. Without proper elimination, uric acid forms into monosodium urate crystals, which can then create stones within the various parts of the urinary system, or accumulate in tissues and joints.
Gout, or urate deposition, is a condition wherein uric acid deposits on joints or tissue surface in birds. Urate deposits are semisolid to solid white masses that can swell the areas where they accumulate, resulting in pain and mobility issues. Depending on where the accumulation occurs, it can cause rigid toes, swollen joints, and difficulties perching, or elimination and neurological problems.
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Symptoms of Gout in Birds
Urate deposits can affect the mobility of birds, as well as kidney function, which can cause many of the symptoms seen. Symptoms can resemble those of renal disease, which may very well be present in your bird. Signs to watch for include:
- Swollen, warm, and rigid toes
- Swollen, painful joints
- White deposits near joints that are visible through the skin
- Ruptured swellings
- Feather picking over the synsacrum area
- Dramatic increase or decrease in amount of urine
- Lack of urination
- Excessive thirst
- Loss of appetite
- Weight loss
- Generalized weakness
- Decreased muscle mass
- Neurologic signs
- Loss of body movement control
- Difficulty flying and perching
There are two recognized types of gout in birds, which commonly occur concurrently in the same bird.
Visceral gout is characterized by urate deposition on tissue surfaces, where it appears as a white coating. Urates also deposit within organs, such as the pericardium, spleen, and liver. This type of gout is the most common in poultry, where it is often a secondary condition that results from urolithiasis. Visceral gout is also commonly caused by renal failure.
Articular gout, or synovial gout, is rare to find alone, and is more often seen in birds who also have visceral gout. This type causes urates to be deposited as solid, chalky substances in toes, joints, synovial membranes and tendon sheaths of joints. These deposits cause inflammatory swelling and pain. Articular gout is often caused by excessive protein in the diet, or hereditary defects affecting uric acid metabolism.
Causes of Gout in Birds
Urate deposition in joints, tissues and organs results from elevated levels of uric acid in the blood, or hyperuricemia. This, in turn, is caused by a dysfunction in the normal process of uric acid metabolism, and can be traced to problems within the diet, kidneys, or urinary tract. There are many factors that can cause these elevated levels, which include:
- Excessive protein in the diet
- Renal disease or failure
- Obstructed ureters
- Urolithiasis, or the formation of stones in the urinary system
- Hereditary defects that affect uric acid metabolism
- Viral infections, such as infectious bronchitis virus, avian nephritis virus, and Type A influenza
- Exposure to mycotoxins, such as oosporein
- Nephrotoxin exposure, such as to aminoglycoside, potassium dichromate, or mercuric chloride
- Exposure to pesticides, herbicides, or other toxins
- Exposure to heavy metals
- Deficiency of vitamin A or B12
- Diet high in calcium
- Incorrect amino acid balance in diet
Diagnosis of Gout in Birds
A diagnosis begins with symptoms and a history of your bird’s environment, health, diet, possible exposure to toxins and infections, genetic background, and behavior. Be sure to notify your veterinarian if your bird has recently had dietary changes or supplementation. A physical exam can reveal painful areas and abnormalities.
Various tests will be run, which can not only reveal elevated uric acid levels, but also the presence of any toxins, infections, or renal diseases. Tests include bloodwork and serum testing, microbiologic assays, cultures and various stains, microscopic examination, urinalysis, fecal flotation, and aspiration using a fine needle to find the presence of uric acid crystals.
Renal scintigraphy, X-rays, MRIs, CT scans, and ultrasounds can be used to assess kidney and organ function, and will be able to help determine if a renal disease is affecting your bird. A biopsy of the kidney is the only definitive way to confirm the type and severity of renal disease, and can be performed in several ways, including by endoscopy.
Treatment of Gout in Birds
Many conditions of gout and renal disease can be managed through medical and supportive treatments, aimed at treating the cause of the disruption in uric acid metabolism. Surgery can be difficult, and may only be needed in severe cases.
Aggressive fluid therapy is administered if the gout is accumulating rapidly, along with electrolyte and diuretic medications, such as mannitol or furosemide, to encourage elimination through urine. Your bird’s diet will most likely be modified to fix any imbalances, such as protein and calcium levels, and may seek to add whole grains, fruits and vegetables. Supplementation of parenteral vitamin A or omega-3 fatty acids are often prescribed, especially in cases of renal disease.
Allopurinol may be given to aid in decreasing the production of uric acid in your bird, while colchicine is prescribed to reduce hyperuricemia. They are often used together until signs of hyperuricemia and gout are resolved.
Surgery can be performed to remove uric acid deposits within joints and tissues, with the use of anesthesia. Renal disease may also benefit from surgery to remove stones, or damaged kidneys, but can be more difficult.
Recovery of Gout in Birds
Recovery of gout is variable, and depends on the severity of your bird’s condition and any concurrent conditions that may have caused the gout. Renal diseases can be fatal, and many carry a poor rate of recovery. Some conditions can be resolved or managed. Your veterinarian will discuss your bird’s chances of recovery based on his particular case.
At home, you will need to make dietary changes as needed, and administer any medications or supplements recommended by your veterinarian. If surgery was performed, you will likely need to change bandages and provide supportive care. Your veterinarian may perform more testing during treatment to monitor your bird’s progress.