Investigating Embryo Deaths and Hatching Failure Bruce A. Rideout, DVM, PhD, Dipl. ACVP  Veterinary Clinics: Exotic Animal Practice  Volume 15, Issue 2, Pages 155-162 (May 2012) DOI: 10.1016/j.cvex.2012.02.005 Copyright © 2012 Elsevier Inc. Terms and Conditions

Fig. 1 The six most common types of malpositions in late-stage embryos. (1) Head over the right wing (not usually lethal). (2) Head under the left wing (causes moderate to high mortality). (3) Rotation away from air cell (moderate to high mortality). (4) Leg over the head (high mortality). (5) Upside down (high mortality). (6) Head between the legs (high mortality). Veterinary Clinics: Exotic Animal Practice 2012 15, 155-162DOI: (10.1016/j.cvex.2012.02.005) Copyright © 2012 Elsevier Inc. Terms and Conditions

Fig. 2 A California condor (Gymnogyps californianus) egg opened around the aircell showing a head under left wing malposition. The beak is evident in the upper left quadrant. When the head is under the left wing instead of the right, it results in a body orientation that requires the embryo to reach the upper slope of the air cell in order to pip. This embryo was not able to reach the air cell and died during pipping. Veterinary Clinics: Exotic Animal Practice 2012 15, 155-162DOI: (10.1016/j.cvex.2012.02.005) Copyright © 2012 Elsevier Inc. Terms and Conditions

Fig. 3 A stage 44 kea (Nestor notabilis) embryo that died during pipping as a result of a fetal membrane entrapment (the yolk sac is wrapped around the back of the neck). As the yolk sac began to retract in preparation for hatching, it tightened itself around the back of the neck, preventing the normal head movements required for pipping. There is prominent edema of the head and neck accompanying the constriction. Veterinary Clinics: Exotic Animal Practice 2012 15, 155-162DOI: (10.1016/j.cvex.2012.02.005) Copyright © 2012 Elsevier Inc. Terms and Conditions