Increased Mortality in a Colony of Zebra Finches Exposed to Continuous Light

Over a 1-mo period, increased morbidity and mortality occurred in a flock of zebra finches (Taeniopygia guttata). Complete postmortem examination was performed on 6 of the affected birds, 4 of which subsequently were diagnosed with the avian gastric yeast previously known as megabacteriosis (Macrorhabdus ornithogaster). The remaining 2 birds were diagnosed with a cloacal abscess and with large bowel perforation and peritonitis. All the birds had been prophylactically treated with amphotericin B for megabacteria 2 mo previously. An environmental assessment revealed that the light cycle had been altered, and the birds were being exposed to constant light. With correction of the light cycle, the health of the birds improved dramatically. The remaining birds were treated again with amphotericin B, and baseline mortality returned to normal. The birds in this report show several similarities to previous reports of sleep deprivation syndrome in mammals.Over a 1-mo period (from late April to late May 2011), a marked increase in morbidity and mortality was noted in a flock of zebra finches (Taeniopygia guttata) at our facility (University of Washington). These birds were involved in a project studying the neural mechanisms of vocal learning. The finches were obtained from Magnolia Bird Farm (Anaheim, CA). In March 2011, a shipment of 50 male birds arrived and was moved into a new space with 2 rooms. One room housed breeding birds in cages containing breeding pairs and offspring; the other room, into which these new arrivals were placed, housed adult male birds in cages of 4 to 9 birds.Birds in the room containing the adult nonbreeders were affected exclusively. Clinical signs consisted of puffed and ruffled feathers, lethargy, increased respiratory effort, and feather loss. These signs were noted in birds that had not undergone experimental manipulation. Several of the birds that died or were euthanized after becoming sick and lethargic were necropsied. Findings on postmortem examination for the majority of cases included emaciated body condition, necrotizing enteritis and colitis and, in individual cases, included bowel perforation and peritonitis and severe pyogranulomatous abscessation. Megabacteriosis (avian gastric yeast; Macrorhabdus ornithogaster) was diagnosed histologically in 4 of the 6 birds evaluated. A light meter was placed in the housing room; results showed that the dark period of the light cycle was absent. The light cycle was corrected, and morbidity and mortality decreased dramatically.