Day  9
The  "embryonic vesicle," which houses  the embryo, is the only part of the egg  visible at 9 days. The vesicle appears  as a translucent bubble, less than a quarter  inch in diameter. Upon an ultrasound screen,  it will be visible as a black circle within  a large grainy gray background (your mare's  uterus). At this point, the embryo is  smaller than a pinpoint.

Day  24
The vesicle will grow to 1 inch in diameter. It's a shimmering, flabby, translucent bubble with a dark red embryo at one end. A network of threadlike blood vessels  grows out a quarter inch from the embryo. Beginnings of animal features (such as:  a head with small eyes, a fleshy tail  nub, and four smallish buds that will  eventually grow into legs. On the ultrasound  monitor, you will see the vesicle as an  irregular, guitar-pick shaped black dot  in a grainy gray backdrop. Generally,  around Day 24 an embryonic heart is large  enough to be seen on the ultrasound screen.  To find it, focus on the bottom surface  of the embryo. You will see a white smudge,  about a half inch in diameter, resting  there. Within that smudge, you will see  a tiny black dot, about the size of a pinpoint, that will be flashing on and  off like a computer's screen's cursor;  this is the pea sized embryo's beating  heart.

Day  40
The  vesicle is now 2 ½ inches in diameter, roughly spherical in shape, and somewhat collapsed. The ¾ inch embryo within  is now
recognizable as a four-legged critter:  it has a blobby dome for a head, eyelids, rudimentary ears, ridges where the nostrils will be, and functional elbows an stifle  joints. An ultrasound would reveal the  vesicle as a roundish black blob: look  the white smudge of an embryo to be suspended  from the blob's ceiling, rather than resting  on its floor. This shift of position is  step one in what researchers call "the  rise and fall of the embryo." It  results from filmy membranes at the top  of the vesicle coming together to form  the umbilical cord. As they do so, they  shorten, pulling the olive-sized embryo  up to the ceiling like a chandelier.

Day  50
The embryo is now slightly over an inch  long, nesting within the confines of the  3-inch vesicle. You can see tiny ribs  under its skin; its domed head looks like  that of a Chihuahua, and has developed  a distinct skull. Little triangles represent  its ears; the hock and fetlock joints  have developed. At this stage, your future  foal officially will graduate from embryo  to fetus. On an ultrasound monitor, you'll  find the fetus back on the vesicle's floor,  due to a lengthening of the umbilical  cord. Because of its size-now about that  of a pecan; this will be your last opportunity  to view the fetus via ultrasonography;  in a matter of weeks, it'll be too large  for the screen.

Day  60
The  vesicle is now flabby and shapeless, conforming  to the uterine walls; the fetus is about  2 1/2 inches long. You can see that it clearly resembles a horse, thanks to the developement of tiny hooves, complete with soles and frogs. Its head is still tucked,  but less so than before. The fetus is  hairless, and about the size of a hamster.



Day  80
The fetal head and neck will be untucked,and are being held level with the spine  in the "normal" horse position.  Its sex is now visable: you can see that  little lumps have formed for the scrotum,  if it's a male, or the udder, if its a  female. The fetus is now about the size  of a chimpmunk.




Day  150
Gaining  more than a pound every 10 days, the fetus  now is about the size of a rabbit. Hair graces its chin, muzzle, and eyelids.  If you look closely, you'll see that eyelashes  have emerged.






Day  180
The fetus has quadrupled its weight in  just 30 days. Mane and tail hairs have appeared; it's about the size of a Beagle.





Day  240
Now  about the size of a small lamb, the fetus  has whiskerlike hairs on its chin, throat and muzzle.





Day  270
Your mare's fetus now looks like a foal:  fine hair covers its body, and it now  has a swatch of hair on its tail. It's  about the size of a German Shepherd.


Day  320
In  the last week or so, the fetus's lungs have developed to the point that they  can function in the "real world";  its legs have strengthened to the point  that they can support it's weight; and  it's hair has coarsened, from the fine,  silky texture of fetus hair, to that of  a bonafide foal. As far as development  goes, the fetus is "done." You'll  get the chance to meet your mares' foal  in a matter of days or weeks. (Normal equine gestation can range from 320 to  365 days.)

    Foal Development Timeline 

Welcome to P.S. Halter Horses
Breeding World Quality 
Quarter Horses and Paint Horses
Copyright: PS HALTER HORSES
                 Pam Simpson
P.S Halter Horses
 Pam Simpson
Willisburg, Ky  40078
(502) 758-0718 cell

Email: pamsummers@hughes.net