Metabolic bone diseases such as osteomalacia (thinning of cortices and demineralization of bone) and rickets (inadequate calcification
of osteoid in growing birds) are the result of calcium, phosphorus and vitamin D3 deficiencies or an improper calcium:phosphorus in the diet.
Clinical signs of osteomalacia or rickets may include fractures, bending of long bones, skeletal deformities (spraddle-leg
in chicks), polyuria and polydyspnea, beak malformations, reproductive problems (abnormal egg shape or difficulty passing
eggs in females) and poor growth in young birds.
Diagnosis is based upon dietary history, clinical signs, physical examination, clinical pathology (especially total plasma
calcium and ionized calcium levels) and demonstration of decreased bone density, fractures or skeletal malformations by radiographic
evaluation. The patient should also be evaluated for underlying hepatic or renal disease.
Treatment involves correcting the underlying dietary deficiency by placing the patient on a commercial formulated diet,
administration of oral or parenteral calcium and supplementation with other dietary sources of calcium such as dark, leafy
Hemochromatosis (Iron Storage Disease)
Hemochromatosis results from the excessive accumulation of iron in various body tissues, but most frequently in the liver.
Although, it may occur in Psittacines and other species, it is most commonly reported in toucans and mynah birds. The exact
etiology is poorly understood; however, excessive iron (greater than 100 ppm) in the diet, one or more inherited metabolic
defects, altered iron absorption from the intestines, concomitant disease, dietary changes or heavy metal toxicoses may contribute
to the development of the disease.
Clinical signs most commonly include dyspnea, distension of the coelomic cavity due to ascites and weakness. Toucans may not
show any clinical signs or may be depressed for a day prior to death while mynahs may exhibit weakness, coughing, dyspnea
and distention of the coelomic cavity.
The diagnosis of hemochromatosis is based upon history, clinical signs, physical examination, radiographs and cytologic evaluation
of the ascitic fluid. A definitive diagnosis requires biopsy and histopathologic examination of the liver.
Treatment of hemochromatosis requires aspiration of the ascitic fluid to relieve dyspnea, placing the bird on a commercially
prepared low-iron diet and phlebotomy. Draw 1-2 mls of blood every 24 hours until clinical signs improve or the lower limit
of the normal hematocrit is reached. The hematocrit should be measured with each phlebotomy. Blood is then drawn weekly at
a rate of 1 percent of the bird's body weight in grams. Phlebotomies are discontinued and the patient is monitored when the
hematocrit falls below normal. Total serum iron, albumin, hematocrit, repeated radiographs and body weight may be useful for
monitoring treatment. Deferoximine (100 mg/kg subcutaneously q 24h) (Desferal, Ciba-Geigy Corp., 556 Morris Ave, Summit, NJ
07901, USA) in conjunction with a low-iron diet has been used to treat hemochromatosis.
Dr. Jones is asssistant professor of avian and zoological medicine at the University of Tennessee's College of Veterinary
Medicine. He is a diplomate of the American Board of Veterinary Practitioners—Avian Specialty. Dr. Jones' clinical interests
include raptor medicine, orthopedic and soft tissue surgery, avian nutrition and avian infectious diseases. He is also a master
falconer with 15 years experience.