Here are two of the ultrasound images taken by Dr. Wilcock at Evergreen Veterinary Hospital on April 4. When you click to enlarge you will find the top image is a close-up of the lower image. The dark "blob" that you see is a puppy. The other shadowy "blobs" are also puppies. Dr. Wilcock is estimating a litter of 8 to 10.
Excerpted from the wonderful book, Canine Reproduction, by Phillis A. Holst, MS, DVM, this is a fascinating summary of prenatal development.
Following the "Average Day Post-Breeding" number is the estimated date, based on the date of Keeper's last breeding (March 8).
| Average Day Post-Breeding | Stage of Development |
| 1 (March 9) | In estrust, pre-ovulation. |
| 2 (March 10) | Ovulation, primary oocyte. |
| 3 (March 11) | Primary oocytes have moved to distal portion of oviduct, meiosis is occurring. |
| 4 (March 12) | Secondary oocytes ready for fertilization. |
| 5 (March 13) | Fertilization occurs. |
| 6 (March 14) | First cleavage division of ovum begins. |
| 7 (March 15) | Two-cell embryo in oviduct. |
| 8 (March 16) | Four-cell embryo; going out of heat. |
| 9 (March 17) | 8-16 cells in a cluster. |
| 10 (March 18) | 16-32 cells, a morula. |
| 11 (March 19) | 32-64 cell morula enters the uterus. |
| 12-18 (March 20-26) | Blastocyst forms, floating free in uterus. Individual blastocysts become spaced evenly along horns of uterus. Grow from 1/4 mm to 2 mm in diameter. |
| 19 (March 27) | Implantation begins. Uterine response in a bandlike area around each embryo, suggesting the shape of the placenta that is developing for each embryo. |
| 20 (March 28) | Embryo body begins to take form as a linear thickening of cells, the primitive streak. |
| 21 (March 29) | Primitive body segments, or somites, begin to take form. |
| 22 (March 30) | Ten or more somites have formed. Primitive brain and spinal cord growing. Head portion of embryo bends forward. |
| 23-25 (March 31-April 2) | Limb buds form, embryo grows in length from 5 to 10 mm. |
| 26 (April 3) | Limb buds paddlelike, 11 mm. Swellings along uterus at site of each implantation may be large enough to palpate for pregnancy detection. |
| 27 (April 4) | Eyes begin to have pigment in retina, body taking form, face taking shape. Keeper is due to have her ultrasound. |
| 28 (April 5) | Facial features more defined, individual nipples are seen, 14-55 mm in length. |
| 29 (April 6) | Toes take shape, whisker buds are visible, umbilical cord forms, 18 mm long. |
| 30-32 (April 7-9) | Differentiation of detail of face & limbs until facial features are definitely doglike. 22 mm in length, 1 gram (1/30 oz.) weight. |
| 33 (April 10) | Male/female sexual characteristics can be differentiated. 24 mm in length. |
| 34 (April 11) | Digits & claws are differentiated. Eyelids, which are at first open, close. 30 mm in length, 2 grams weight. |
| 35-40 (April 12-17) | Growth & differentiation of external and internal details. Reaches 45 mm in length and 6 grams in weight. Skin pigment begins to be visible. |
| 41-63 (April 18-May 9) | Further growth and differentiation of the fetus. Puppies typically born between days 59-63. |