Morphologic Diagnosis Skin (comb, wattles): Severe acute edema and hemorrhage. Skin (face): Severe edema. Skin: Dehydration. Clinical Description This image was taken 3 days post experimental inoculation with highly pathogenic avian influenza. There is bilateral edema on both sides of the face. Edema of the face is easiest to appreciate by observing the bird head-on. Squaring of the head over the eye region, is associated with periorbital edema and is a common clinical sign observed in HPAI. Pathologic Description The subcutanous tissue of the comb, wattles and face is extremely swollen. The swelling of the face gives the head a square appearance. There are large dark purple areas on both the comb and wattles. The unfeathered skin is dry and wrinkled.