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.