Yolk Sac Retention in the Ostrich (Struthio camelus): Histopathologic, Anatomic, and Physiologic Considerations

Preliminary study: Health and performance assessment in broiler chicks following application of six different hatching egg disinfection protocols

“…Indication for nephritis or nephrosis [48] multifocal to diffuse white, crystal-like alterations specific indication for urate deposition [41] Yolk sac Still present/larger than anticipated, wall thickened, with content Yolk sac retention, indication for retarded development or low-grade non-specific inflammatory process [41,49,50,51] Thickening of the wall, reddening or vascular infiltration, adhesion to inner organs, exudate…”

“…Macroscopically, the presence of yolk sacs in 7-and 14-day old chicks is a parameter for impaired chick development. [50,51] During necropsy, we differentiated between yolk sac retention and yolk sac inflammation, but the number of inflamed yolk sacs was low, so that only differences in the number of normal and abnormal yolk sacs were evaluated statistically, thus combining the afore mentioned categories. The distribution of abnormal yolk sacs showed a tendency towards the ESBL producing E. coli contaminated groups A and B. Deviations of texture and colour of the kidneys were noted, but appeared to be distributed inconsistently between the groups, indicating that the findings were of an unspecific nature.…”

IMAGING DIAGNOSIS—USE OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF A MINERALIZED YOLK SAC IN A BROWN KIWI (APTERYX MANTELLI)

“…A New Zealand conservation management program based on rearing chicks in controlled environments has increased their chance of survival to adulthood to 65% compared to less than 5% in kiwi from unmanaged wild populations.In a recent study involving 406 kiwi chicks raised in captivity, 4.3% of them presented with retained or infected yolk sacs . Yolk sac retention is a recognized cause of early death in this species and in other ratites . Due to the conservation status of kiwi, early diagnosis of yolk sac retention is important in clinical decision making and subsequent chick survival.…”

Palaeognathae: Apterygiformes, Casuariiformes, Rheiformes, Struthioniformes; Tinamiformes

“…Due to the common occurrences of yolk sac retention in ostriches, an understanding of normal is critical. A microscopic description of the normal and abnormal yolk sac of the ostrich has been published by Dzoma and Dorrestein (2001). A predictive curve for yolk sac size was developed, with the amount of yolk predicted to be 33% of chick weight on day 1 after hatching, as compared to 4% at 14 days posthatch.…”