Radiographic Measurements of Internal Organs in Rhode Island Red Hybrid Hens (Gallus gallus domesticus) and Their Evolution During Egg Formation

Abstract

Backyard poultry hens are becoming very popular as pets, and thus the demand for treating the individual chicken is increasing. Few basic diagnostic techniques commonly used in small animal practice have been evaluated in this species. At the moment, there is no study in backyard hens describing radiographic measurements of internal organs contrary to psittacine birds or birds of prey. Moreover, the effect of egg laying on these measurements has not been studied in avian species even though it could affect radiographic measurements depending on the stage of egg formation. This is of particular concern in laying hens since they are able to lay on a daily basis. Thirteen adult hens and 3 juvenile Rhode Island red hybrid hens (Gallus gallus domesticus) were used to evaluate which organs can be reliably measured and to provide preliminary reference values for clinically healthy chickens. Additionally, whole body radiographs were collected every 2 hours over 24 hours in 5 adult hens to study the evolution of these measurements throughout egg formation. Organs that could be clearly delimitated on radiographs were measured, and the only organs that could be reliably measured were the heart and liver silhouettes. These measurements were significantly higher in adult compared to juvenile hens (P = 0.024). Among the different organ ratios, heart width: total liver width ratio was the only significantly different measurement and was higher in juvenile hens (P = 0.024). Hepatic silhouette measurements and ratios were found to increase over time (P < 0.02) but did not follow the progress of egg mineralization. Eggshell thickness was found to be a promising parameter to evaluate the stage of egg formation, and thus should be taken into account when trying to establish reference intervals for radiographic measurements of internal organs in laying hens.