Reduced birth weight, cleft palate and preputial abnormalities in a cloned dog

The aim of the present study was to report a novel developmental abnormality in a cloned dog. A fibroblast cell line was established from an 8-year-old male German shepherd dog. In vivo matured oocytes were retrieved from a large breed dog, and the nucleus was removed from each oocyte. A donor cell was injected into an enucleated oocyte, and the oocyte-cell couplet was fused electrically. After chemical activation, the resulting embryos were transferred into a naturally estrus-synchronized recipient dog, and two cloned pups were delivered by Cesarean section 60 days later. One cloned pup (Clone 1) was healthy, but the other (Clone 2) had a birth weight of only 320 g and cleft palate, failure of preputial closure at the ventral distal part, and persistent penile frenulum. Clone 2 was raised by stomach feeding until Day 40 after birth, where palatoplasty was performed. The abnormalities in external genitalia in Clone 2 resulted in persistent penile extrusion that was surgically corrected. This complex developmental abnormality has not been reported in dogs previously.