Visceral Gout in Birds

Margrethe Warden

 

Of the many health concerns plaguing caged birds, one that seems to appear often enough to cause some concern is gout, which is brought on by the build up of uric acid Uric acid is produced by the liver and excreted through the kidneys. It is the result of metabolizing nitrogen that is present in the food. The uric acid itself is not toxic or harmful but the build up of crystals can severely damage body tissue. The build-up of uric acid crystals is the result of the inability of the kidneys to remove from the blood the waste products resulting from nitrogen metabolism.  The uric acid, when not properly removed from the blood stream, will begin to crystallize and collect in various places in the bird’s body.  Accumulation in the joints and surrounding tissues, usually in the legs and feet, is articular gout. This is considered to be the chronic form of gout and it presents as swelling in the joints and can cause the inability to properly balance and perch or lameness. Visceral Gout is build up of uric acid crystals in the various internal organs (viscera) and it is considered the acute form of the disease.  I first encountered visceral gout in 1995 after the necropsy of my first lory, a four year old male red (Eos bornea), and I have seen and heard of it in a number of birds since that time. 

The exact cause of visceral gout is not clear but it appears there are a variety of factors that might cause a predisposition. It is often associated with high levels of dietary protein and calcium, Vitamin D3 hypervitaminosis, insufficient levels of Vitamin A and even lack of sufficient water supply. Other factors such as toxins, viruses, bacteria, other infections or metabolic disorders and stressors can interfere with kidney function and precipitate a problem. 

Visceral gout is most often seen during a necropsy and is difficult to diagnose in a living specimen. The most frequently seen sign of the disease is sudden death.  The symptoms, if there are any, are vague and non-specific and can include depression, lethargy anorexia, feather plucking or other behavioral changes. Absent definitive symptoms, uric acid levels can be routinely monitored. If the levels become elevated, an endoscopic procedure can diagnose gout. 

If it is diagnosed in a living specimen it is difficult, if not impossible, to treat and the prognosis is poor. Visceral gout cannot be “cured” but it can be managed to some extent and steps can be taken to prevent further uric acid build up. Exercise is important in treating the problem. Other treatments can include a diet heavy on the natural vegetable, fruits and Vitamin A and low in protein. There are some allopathic drugs such as Allupurinol, which can lower uric acids levels and have been used in birds with varied results. There are also several homeopathic treatments that might prove useful in managing this disorder. 

While high protein levels have been associated with visceral gout there is no evidence that healthy kidneys in a bird will be harmed by excessive dietary protein.  Birds in captivity; however, are often exposed to a host of toxins and pathogens that unbeknownst to the owner can cause damage to their birds’ kidneys. It is at that point that dietary protein levels become a potential hazard. 

Visceral gout has shown up in a variety of avian species. It is not uncommon in egg producing poultry flocks and is just as difficult to diagnose in chickens as it is in caged birds. Often the affected chickens show no symptoms and produce normally until they are close to death. Research indicates that infections such as viral bronchitis and nutritional factors such high levels of calcium in the diet, along with exposure to toxins, may be the cause of visceral gout in these poultry flocks. The repeated occurrence of visceral gout in pionus parrots gave rise to the Pionus Parrot Research Foundation (http://www.fatparrots.org), a not for profit organization whose primary purpose is to study the natural diet of pionus parrots in the Mindo Valley of Ecuador. Prior to establishing this organization there had been only one serious study of the diet of wild pionus parrots. While this research project is ongoing, information extrapolated thus far suggests that the pionus in the wild have a dietary protein level of about 3% - 6% when it is not breeding season.  Most commercially manufactured avian maintenance diets in the US have levels ranging from 11% - 14%. For this reason, many pionus breeders and enthusiasts recommend feeding their birds a varied diet of fresh vegetables, fruits and freshly sprouted seeds while offering pellets only as a small percentage of the total food intake. 

Unlike many other avian disorders, visceral gout is not exclusive to our captive companions or domestic poultry. Research conducted by the Peregrine Fund into the causes of death in Asian vulture species has shown visceral gout to be a reoccurring finding during necropsy. The gout is unlikely to be the result of dehydration as drinking water is consistently available all year. The condition was no more common during periods of high temperature or during periods of low rainfall. While a variety of pathogens have been linked to visceral gout no specific one were found in the tissue cultures. Similarly, while the vulture diet and range could potentially expose them to a number of harmful elements, none were found present in histopathology. 

While visceral gout is hard to detect and difficult to treat once discovered, monitoring uric acid levels can be a useful tool for detecting and managing birds with this disorder. Annual check ups, plenty of clean fresh water and a good balanced diet are factors that can help keep your birds free of this disease. 

Comparative Avian Nutrition;  Kirk Klasing, CAB International, New York, 1998. 

The Asian Vulture Crisis; The Peregrine Fund; www.peregrinefund.org/conserv_vulture.html 

AVIAN UROLITHIASIS (Renal or Visceral Gout), Dr. Bernie Beckman, Technical Bulliten Hy-Line International 

Diet of the Scaly-headed Parrot (Pionus Maximiliani) in a Semideciduous Forest in Southeastern Brazil, Mauro Galetti, Biotropica, 1993 

Thanks to Heather Wilson DVM, ABVP Dipl.  of the University of Georgia for ensuring I was accurate with my information.

 

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