Epizootiology, pathology, and microbiology of an outbreak of urolithiasis in chickens.

An outbreak of urolithiasis that doubled the annual mortality rate of chickens in a large flock of table-egg-layers is described. Despite the presence of a large unilateral urolith and/or severe renal atrophy, the layers often maintained active egg production and apparent homeostasis until a small urolith blocked the ureteral flow from the contralateral kidney. This terminal episode appeared to produce acute obstructive renal failure, rapidly developing visceral gout (visceral urate deposition), uremia, and death. The atrophy observed appeared to be acquired and progressive. Histologic features in the kidneys were acute to chronic glomerulonephritis, interstitial nephritis, and pyelonephritis. Epizootiologic and microbiologic studies indicated that a combination of infectious and noninfectious mechanisms may have been involved. Causative roles for calcium-phosphate imbalance, infectious bronchitis (IB), Newcastle disease (ND), and adenovirus or reovirus infections could be neither excluded nor confirmed. Contributory factors may have been spray ND-IB and other vaccinations of 15-week-old ND-IB-susceptible pullets, water deprivation, shipping stress, Mycoplasma synoviae infection, immune complex disease, and mycotoxins.