Radiographic Measurement of Internal Organs in Gyr Falcons (Falco rusticolus) and Gyr Peregrine Hybrids (Falco rusticolus × Falco peregrinus)

Falconry in the Middle East is an increasingly popular tradition favoring the hunting skills of large falcons including the Gyr falcon (Falco rusticolus) and Gyr peregrine hybrids, particularly Falco rusticolus × Falco peregrinus. Radiography allows investigation of avian skeletal disease as well as evaluation of organs of the coelomic cavity. To objectively interpret radiographic images of the avian coelomic cavity, one must master normal radiographic anatomic size and position of internal organs in healthy birds of the same species. This study provides standardized radiographic measurements of Gyr falcons and Gyr peregrine hybrids. These measurements would serve to aid veterinarians in the interpretation of radiographic images of not only Gyr falcons and Gyr falcon hybrids but also other raptor species of similar size. Radiographic measurements of the heart (HW), liver (LW), cardiohepatic waist, kidneys, spleen, proventriculus (PW), thoracic width (TW), and keel of the sternum (HK) were obtained under standardized conditions in clinically healthy Gyr falcons (40 females and 15 males) and Gyr peregrine hybrids (40 females and 15 males). Ratios were determined for the proventricular diameter to keel height (PW:HK), the width of the heart to the width of the thorax (HW:TW), and for the cardiohepatic ratio to the LW (HW:LW). Significant organ differences (P < 0.001) were found between sexes, with females of both the Gyr falcon and Gyr peregrine hybrids having larger organs than the males of each respective group. Gyr females had significantly (P < 0.001) larger HW, TW, and HK than female hybrids.