Fetal ECS Ultrasound Images

I (Danae) am a Perinatologist by training (perinatology is a subspecialty of Ob/Gyn which specializes in the care of women with high risk pregnancies.) As part of that training and practice I have a lot of experience doing ultrasounds, and have not been able to resist my curiosity to see fetal puppies. All these pictures have been taken of English cocker pregnancies, mostly of my own dogs, but also dogs belonging to my friends who have humored me.

A couple of important things to know about ultrasound pictures are that fluids (like blood, or amniotic fluid) show up as black, and bones (at least once they have some calcium in them) show up as bright white. Other tissues are usually somewhere in between, in shades of grey. Ultrasound takes pictures which are a 2-dimensional "slice" through a solid form. Its like taking a slice out of a loaf of bread and looking at it. It also takes some patience to get used to looking at ultrasound pictures. At first they may just look like grey mush, but as you get more experienced they start to make sense. So, have patience with yourself if you can't see what I say is there!



21 days after the first breeding is the first time I have been able to see actual puppies. This embryo is 3mm long but had a heartbeat. The little stars you will see on some of these pictures are how you can measure something you see on an ultrasound picture. So if there are stars, that is usually the important part of the picture....



Here you can see 2 sacs next to each other. Dogs have a bicornuate uterus, which means the uterus is divided into two horns, one on each side of the belly. Puppies in their sacs tend to be arranged up each horn like peas in a pod.




At 25 days, the embryo measures 7.5 mm long.



This is the embryo at 33 days. It now measures 2 cm (not quite an inch) long.



You can start to see a hint of the front and back legs of the puppy. At this point the head takes up about 1/2 the length of the puppy. The head is to the left, the body to the right, and you can see the beginning of rear legs fairly clearly to the far right of the fetus.



The heart rate is 221 beats per minute. This is a LOT faster than a human embryo of the same size. A human embryo would have a heart rate of about 100 bpm.



At this point (32-33 days), you can also see the early spine, which is visible here as the two roughly parallel white lines.



At 42 days the puppy's sacs are starting to look more crowded together. Here you can see 3 sacs.



You can start seeing a lot more anatomy at this point. This is a cross-section of the puppy's abdomen, right beneath the chest. The black circle is the puppy's stomach. It is black because it is filled with amniotic fluid which the puppy swallows.



This is a picture of the puppy's chest. You can see the ribs on the left side (remember, you are looking at a cross-section of ribs in this view, so they look like a row of white dots.) Within the chest is the heart which is black because it contains blood. The abdomen is on the right. Between the chest and abdomen is a line between the lighter shade of gray on the left and the slightly darker one on the right, which is the diaphragm, the muscle that separates the chest from the belly.



This is the puppy's face. You are looking at the bony skull (remember that bones show up as fairly bright white). The backskull is to the left. Then you can see an eye socket as you move right, and then the bones of the nose are to the right of the eye socket. The long thing stretching out in front of the nose is some other extraneous puppy part, probably part of a foreleg.



You are looking at a cross-section through the puppy's brain. The areas on either side of the midline are the lateral ventricles (one of them is marked wish the stars), which are fluid-filled spaces on either side of the brain. Within the lateral ventricles is gray stuff called the choroid plexus, which is a spongy tissue where the spinal fluid is made.



You can see the layers of membranes of the sacs surrounding each puppy. This picture is interesting to me because amniotic membranes in humans (such as you would see in a twin pregnancy) are MUCH thinner than these. In fact, it can be hard to see the membrane between twins, and no one would miss these membranes in a dog pregnancy.



This is the spine again. At 44 days (12 days after the first picture I showed you of the early spine, you can see the brighter spots of each individual vertebrae.



The heart rate of this puppy at 47 days is 235 beats per minute.



This picture was taken at 50 days and shows a lot of fluid under the skin of the puppy's neck and back. The head is to the right and the body to the left. The black on either side of the neck is a lot of extra fluid. If you saw this in a human fetus you would be extremely concerned that the baby had some kind of serious problem and would be likely to either be stillborn or die after birth, but I have seen this many times in puppies as they get near delivery, and it seems to be normal. My guess is that this is where the puppy stores the extra fluid it needs after birth so it doesn't get dehydrated while its figuring out how to nurse effectively, and the mother's milk is coming in.



The rest of these pictures are also from a 54 day pregnancy. This is a cross-section through a puppy's pelvis. The black spot here is the puppy's bladder. Puppies urinate in-utero, and this fluid forms the bulk of the amniotic fluid.



This is the puppy's heart, and you can see the aortic arch. The aorta leaves the heart heading towards the head, but then makes a 180 degree turn to head towards the tail. The turn is what is called the aortic arch. If you look closely you can see small blood vessels which leave the arch towards the head and neck. Remember that blood (and blood vessels) looks black on ultrasound because it is a fluid. You can also see some of the lower ribs to the left in the picture.



This looks a little eerie, but what you are seeing is the lens of the puppy's eye.



The thick white thing, marked with the stars, is the femur, the long bone of the thigh.



You can see the tail coming off the base of the spine in this picture. You just don't see this in humans!



And finally, my favorite picture of all. You can see the puppy's lips and nose, and a paw alongside the nose as well. Imagine you are looking straight at the puppy's nose from the front (like you are going to look up its nostrils). The nose is to the far right. To the left of that are the upper lips. To the left of the upper lips is the lower lip and chin. The mouth is slightly open so you see a line of black amniotic fluid between upper and lower lips. The paw is underneath the mouth.



This is a 3D picture, one of the newest advances in ultrasound technology, which allows you to see surface characteristics of an object, and not just a 2D "slice" through the object. This picture was taken in November, 2007, after my office got a brand new (Voluson 730) ultrasound machine. The fetus is about 6 weeks gestational age.

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