An outbreak of goiter (thyroid follicular hyperplasia) with high mortality in young adult English budgerigars (Melopsittacus undulatus)

An outbreak of goiter (thyroid follicular hyperplasia) with high mortality and morbidity in a flock ofEnglish budgerigars (Melopsittacus undulatus) in southern California is described. Thirty out of 300-400 young adult birds (7.5-10%) had died and 15 (11.25-15%) exhibited signs of illness and weight loss in the previous two to three months. Diet consisted of a commercial mixture (~70% of total feed) that did not contain minerals or othersupplements, and whole oats, carrot and broccoli. Inbreeding occurred but was comparatively limited. Ten live,approximately one-year-old English budgerigars were submitted for necropsy and diagnostic work up. On clinical examination, the birds appeared moderately depressed, had poor to good nutritional state and had variably enlarged thyroid glands. Four birds were subjected to necropsy immediately following euthanasia. The birds had severely enlarged thyroid glands. Histologically, thyroid follicular hyperplasia was observed in all birds examined, while granulomatous thyroiditis and microfollicular adenoma were observed in one bird each. A large number of thyroid follicles were dilated, lined by hyperplastic and hypertrophic cells that in places formed papillary projections andwere filled with blood, aggregates of hemosiderophages, fibrin, sloughed epithelial cells and colloid-like material, while other follicular luminae were collapsed and lacked colloid. The interstitium was multifocally mildly fibrotic.Pharyngeal swab and cloacal swab pool samples were negative for the presence of the Avian Influenza virus matrix gene by qRT-PCR. Gallibacterium anatis biovar anatis and mixed flora were isolated from the liver and lungs of one bird. Mixed flora was also isolated from the kidney of the same bird, and the small intestine, lung, and liver of second bird. No parasite eggs were detected on examination of a fecal pool sample by flotation. Following supplementation of water with iodine and removal of broccoli from the diet, the owner reported weight gain and reduced deaths among birds with goiter; no additional birds were affected. Budgerigars are susceptible to developing goiter when on an iodine-deficient diet or when consuming large quantities of goitrogenic agents including cabbage, broccoli, kale, turnips, rapeseed and soybean. The presence of broccoli and the almost complete lack of minerals inthe diet of these animals were thought to be the culprits for goiter in these animals. Inbreeding may have further contributed to the deterioration of the animals’ condition. Recognition of this condition, which may have recently reemerged or be underdiagnosed, may help improve medical, welfare and trade standards concerning this species in practice.