Environmental factors associated with nutritional secondary hyperparathyroidism in wild birds

Abstract

Six published case reports of nutritional secondary hyperparathyroidism are described occurring in different species of juvenile wild birds worldwide. Gross skeletal deformities are characterised by fractures and curvature of the long bones and beak resulting from an altered calciumyphosphorus ratio in the blood. The histopathologic diagnosis is osteodystrophia fibrosa and parathyroid gland hyperplasia. Deficiency of vitamin D is implicated in the two instances in which this was measured. Environmental factors include: decreased biodiversity of food sources, surface water pollution, seasonal conditions affecting food and exposure to UV light, and sub-lethal exposure to xenobiotics. Evidence is presented on the possible role of xenobiotics in the pathogenesis.

Crossed beaks in a local Swiss chicken breed

“…Different reasons for the occurrence of beak deformities in birds have been proposed: they can result from the underlying bony structure, from a malocclusion of the mandibles or disturbances in the stratum germinativum of the epidermis [ 10 , 17 ]. The occurrence of crossed beaks was reported due to breeding conditions [ 18 ], accidents or traumata [ 19 ], abnormal abrasion of the rhamphotheca [ 11 ], housing conditions [ 8 ], environmental influences such as toxins [ 20 – 24 ] or nutritional deficiencies [ 25 , 26 ], infections [ 27 , 28 ], or genetic causes [ 14 , 23 , 29 – 32 ]. Already in 1934 a simple recessive inheritance for crossed beaks was postulated in the budgerigar [ 33 ].…”

Beak deformity in three bird species from the southwest of the Brazilian Amazon

“…In the case presented here, everything indicates that the pampas parrot donated from CETAS/IBAMA was a captive animal. He was excessively thin (weight: 493.7 g) and probably his diet was low in vitamins and calcium (see Tangredi 2007). The deficiency of these minerals, even when the animal was a chick, may have contributed to the deformity of the maxilla.…”

Beak Deformities in North Patagonian Birds

“…Beak deformities can threaten bird health by affecting feeding and preening (Van Hemert et al 2012). The etiology of the beak deformities in the Alaskan and European clusters is unknown (Handel et al 2010, Harrison 2011), but several possible causes have been found or suggested for other birds: trauma or improper wear of the rhamphotheca (Pomeroy 1962); bacterial, viral, fungal, or parasitic infections (Gartrell et al 2003, Mans & Guzman 2007, Keymer 2008, Galligan & Kleindorfer 2009; liver disease (Lumeij 1994); diseases caused by toxins (Bassir & Adenkunle 1970); mutations due to radiation, extreme heat or neoplasms (West 1959, Møller et al 2007, Owen et al 2007; and nutritional deficiencies, mainly due to abnormal vitamin or calcium metabolism (Tangredi 2007). A new virus, named Poecivirus, has recently been discovered that appears to be related to beak deformities in Alaskan birds (Zylberberg et al 2016).…”