Avian nutrition has greatly improved in the past decade. Pellets and even organic formulated diets are now available, and domestically raised psittacine juveniles generally accept these readily. However, the exact nutritional requirements for individual psittacine species are still largely unknown. Many of the illnesses seen in pet birds have their basis in malnutrition. This includes hepatic disease, renal insufficiency, respiratory impairment, musculoskeletal disease, and reproductive problems. For information on appropriate nutrition in pet birds, see Nutrition: Exotic and Zoo Animals: Nutrition in Birds.
Vitamin A Deficiency
This is frequently unrecognized in its subclinical forms in pet birds. White plaques (hyperkeratosis) in and around the mouth, eyes, and sinuses are typical. Blunting or absence of the choanal papilla is common. Chronic epithelial conditions, eg, pododermatitis, sinusitis, and conjunctivitis, that have been refractory or recurrent often have vitamin A deficiency as the primary etiology. Parenteral vitamin A can be given IM at 100,000 U/kg. Vitamin A precursors, such as spirolina, sprinkled daily over the food are a safe way to supplement birds deficient in vitamin A. The diets of all pet birds should be evaluated for vitamin A content.
Goiter, or thyroid hyperplasia, is no longer common. Classic signs include respiratory stridor, wheezing, or clicking due to the pressure of the thyroid on the syrinx. Lugol's iodine (1 drop/250 mL of drinking water) can be used until conversion to a pellet or seed is accomplished and clinical signs have subsided.
Calcium, Phosphorus, and Vitamin D3 Imbalance
Seed-based diets are well known for their calcium:phosphorus imbalance and amino acid deficiencies. Sunflower seeds, which tend to be selected preferentially by many psittacines, are low in calcium, deficient in essential amino acids, and high in fat. Safflower seeds are actually higher in fat content than sunflower seeds, contrary to popular belief, and also contain inadequate amino acids and calcium.
Acute Hypocalcemia in African Grey Parrots
This syndrome is characterized by weakness, tremors, and seizures. The exact etiology is unknown, although parathyroid hormone abnormalities and UV light requirements in this species are being studied. The administration of parenteral calcium may effect immediate improvement. Differential diagnoses include heavy metal toxicosis, viral infections (PDD, circovirus), trauma, and idiopathic epilepsy. In young birds, especially African Grey parrots, hypocalcemia may present as osteodystrophy, with curvature and deformation of the long bones and vertebrae.
Vitamin D Toxicosis
Although excessive oral calcium intake is not thought to cause clinical problems in most cases, excessive oral vitamin D3 can cause harmful calcium accumulation in tissues such as the kidneys. Supplements should be used carefully, especially in susceptible species (eg, macaws).
Additional Nutritional Concerns
In addition to the well documented nutritional deficiencies in the traditional diets designed for psittacines, described above, the following dietary concerns should also be noted: 1) the relative inability of birds to use the vitamin A in raw carrots due to a lack of cellulase; 2) the potential sensitivity of individual birds to dyes and preservatives that are added to some seed and pelleted foods; 3) the high incidence of hepatic lipidosis, athlerosclerosis, and right-sided heart failure in sedentary captive birds consuming primarily seed diets; 4) the occurrence of hepatic fibrosis and cirrhosis secondary to aflatoxicosis from improperly stored seed and pet-grade peanuts; 5) the difference between food provided by well-meaning owners for their birds to eat (table foods, formulated pelleted diet, vegetables, etc) and what the birds actually consume (seed); and 6) the low palatability of most vitamin and mineral supplements added to water, which are not only ineffectual, but can lead to decreased water consumption and dehydration.
Last full review/revision July 2011 by Teresa L. Lightfoot, DVM, DABVP (Avian)