Reproduction6-Gestation/Pregnancy in horse, cat and dog



well welcome to reproduction six we're on our journey through the reproductive tracts of our focused and focus animals dogs cats and horses and this lesson is really going to concentrate on gestation or pregnancy meaning both the same things of course we're just doing one layer thick of peeling back the onion right in this introductory type material so man we could talk about even just gestation for weeks probably let me show you this diagram I found and we are going to go through some characteristics of the dog cat horse but I wanted to show you this very nice figure about the four types of placental attachments that can occur between the placenta and the uterus now an animal doesn't have a choice like a cat can't say all due Kali de neri first for example or this pregnancy no it's very species specific so let me get my little words over here the cat and the dog have zone airy classification that means there's a zone on the placenta and I'm going to do that in red hopefully it shows up the laser pointer where this chorionic villi then will attach to the corresponding area in the uterus now there's no uterus present in this diagram it's like and I've got some actual pictures of this but there's definitely a zone and it goes all the way around 360 degrees for the dog and cat lo and behold there are some animals I can't remember I want to say bear but don't quote me on that the zone goes like halfway around whatever anyway dog and cat zone arey then the horse has defuse defuse attachment which basically says most of the placenta has little fingers that attach to the uterus because now you know the placenta is where the fetus gets its nutrients from the mother there's no the maternal environment there's no crossing of blood so the two blood supplies of the fetus in them mother are very close and then by diffusion a lot of things get transported back and forth for example the horse the fetus I guess of any of these animals will get oxygen through the placenta and then carbon dioxide generated by the fetus will go and be taken up by the uterus and then the mother gets rid of it from her lungs so in one case the placentas act as the lungs of the fetus because the fetus is not breathing the lungs are not inflated remember in utero we have a aqueous environment but there's still the fetus still needs oxygen so very interesting so now let's talk about the cat and I've got some pictures that people have taken and I'll explain them and talk about them ok here is an entire reproductive tract from a queen taken out i'll orientate you this is caudal this is the vulva the part that we see with the naked eye up you know that's the only thing of the reproductive tract we see from the outside of the animal the rest of this is all in the animal and of course there would be the vagina the cervix I'm just being approximate here because I don't know exactly from the picture can't tell uterine body and then you know this would be the left uterine horn this would be the right uterine horn so I'm I've got the dorsal view of this reproductive tract the dorsal I mean like if we were in the back go looking down at the reproductive tract there are three fetuses developing on the left and two on the right there early enough that they're very still spherical you'll see that when they get older they tend to be oblong but note that there are distinct spheres very important to know that there's distinct spheres this will get another one this is more advanced but again I couldn't find out the stage of gestation when I saw these are these uh pictures so this is further along than the last one I showed you but I'm not sure how far along I believe this is the cervix here so then this would be probably the left uterine horn and that's the ovary and then this is the right uterine horn so here we've got two and two if I am guessing right and finally another picture that this happens to be a cat as well and this is way further along this is probably very close to birth or parturition you can say here's definitely the ovary and they've got it labeled and then this is the uterus and we're looking through the wall of the uterus at the fetus so the fetus the cat fetus is in here here's the zone it's thicker so here this is fluid-filled and we can kind of see almost through the wall the thinner wall of the uterus here the placenta is blocking our view but you can see a lot of blood vessels now I'm not sure how far the uterus goes off to the left of the picture I don't know but this is definitely very close to giving birth okay now we're gonna look at some dog photos and I think maybe when I showed the cat just a second go I forgot to tell you the gestation length is about sixty days or so and lo and behold it's also sixty days for the dog of course you know these animals are born pretty immature so you know sixty days of gestation isn't that long 60 day pregnancy let's look at some of these images here is a beautiful radiograph I'll orientate you and over here on the left side of the screen I think you can see the laser pointer this is caudal over here cranial dorsal-ventral these are the two femurs the thigh bone of the dog obviously that's the backbone but lo and behold you can see the back bones and the skulls of the puppies this is a dog all in a circle skull one two three four you would guess there's four puppies developing in that dog it's you can't really see if they're on the left side uterine horn or the right but definitely the bones have calcified and so then now you can see this we said for fetuses and yes lo and behold I had seen some pictures of the puppies after they were born and there were four of them now I want to bring in this picture you might say wow this is abnormal no this is a dog's uterus in what's called the postpartum state and maybe what I should do is spell that out for you post partum that means after giving birth okay so this is a postpartum uterus and there's a thing that happens with a postpartum uterus it's called uterine involution because the uterus was big had puppies don't know how many puppies there were total in this dog but as the afterbirth the areas were the placenta remember that zone was attached in the dog these are red so I'm gonna it's gonna be hard to see a red pointer on this but see this one here that what is a zone so there was a one placenta there another one three four I can't tell if that's just blood in the uterus or if it was another point of attachment but at least four attachments in that uterine horn and if you can kind of see this looks like the other uterine or because this looks like the body is coming together the point is uterine involution is important because it gets the uterus back I guess I'll leave it up there back in shape for another pregnancy of course not a dog if you remember the Esther cycles dog couldn't get doesn't really get pregnant right away after they give birth or lack a for awhile but it's an important process you were an involution let me just put that over there and get another picture and of course if the dog is having difficulty if the mom is having difficulty giving birth I just wanted to make sure you understand that then you would do a cesarean section and look at this puppy is two seconds old probably here's the umbilical cord still attached to the uterus the placenta the placenta 'sm it still attached to the uterus here and they're ready to cut the umbilical cord and take care of that puppy excuse me and then go for the next puppy but this is I want to bring that word up cesarean section and I guess I didn't know this before but cesarean section it's thought to be named after Julius Caesar because supposedly in history I'm not a history buff or anything but Caesar Julius Caesar was born by this method cutting through the abdominal wall through the uterus and bringing the baby out in this case Caesar Julius Caesar so that's where this name came from cesarean section named after Julius Caesar that's one thing I read someplace okay now we're gonna talk about the horse well before I forget to tell you gestation length and the horses got a little bit of a range on it for horses you know the dogs and cats at 60 days plus your mane – maybe – three days pretty tight little area because it's relatively short the horse most books would say the average length of gestation is about 340 days I mean 340 days that's amazing with a range of maybe let's say 320 to 360 days or you can say a year so it is a little bit on the amazing side how long a horse is pregnant almost a year and let me bring down this photo and I'm not gonna go through the parts of the placenta but I just wanted to show you this picture that this is the placenta that's been taken out of a horse there's no uterus in the view okay so we're not looking at anything uterus but it shows the fetus still attached to the placenta now I don't know the history of this Mayer that had this that where this tissue is coming from the fetus is not viable way too young but I just wanted to show you you know the umbilical cord branches and branches and branches and goes to tiny little areas that it interacts with the uterus and remember we said that was a diffuse attachment the picture on the left is the same tissue on the right but the fetus hasn't been taken out yet so here's the fetus there here's the fetus exposed okay hopefully you're not having lunch maybe I don't know should I have warned people I don't know anyway now listen careful because I'm not this graphic here is not talking about anything about cats dogs and whatever it's the timeline for gestation in a horse okay so way over here they're saying you know 320 days the foal is about three feet long maybe about a hundred pounds okay and what they're saying then is let's go to the far left at a hundred days when a horse is pregnant the fetus is about the size of a cat and it's one pound okay the fetus the full a young foal so we're just trying to equate what size is the foal at a certain day so 150 it's a size of rabbit undern 80 days and sasai size of a beagle the fetus is now at 240 size of a lamb at 270 days that mayor has a fetus that's about the size of a German Shepherd so I thought that was kind of a neat little graphic but you got to remember it's all talking about the horse this graphic reminds me to tell you about how the uterus grows through pregnancy now this is the lateral view of a horse so this is cranial caudal dorsal and ventral and it uses this nice term gravid gravitons pregnant and their first illustration here is of a non gravid uterus and its location so here's the whole reproductive tract of the horse when it's not pregnant and then I believe these numbers are months although I couldn't find out for sure but it does make kind of sense eleven months is like 330 days and that's about you know the length of gestation so there's trying to show the size of the gravid uterus over time and so at eleven months of gestation this whole thing is uterus okay it's gone ventral and it's going cranial right and it looks like way down here in the ventral aspect they're saying it's almost like all the way up to the if Ram so I thought that was a pretty good figure now we're still talking about a horse but I just want to introduce another concept here so here is a little foal that was aborted and I don't know the history so you know animals can have a spontaneous abortion or an induced induced IND you see Edie induced abortion let's assume it was just spontaneous okay and at 7 months of age of fetal age gestational age there's this thing called the crown rump length crown to rump and I got another diagram they'll show you this but it's about 17 inches when you work with animals and you know you work with enough animals you'll see some that are aborted every once in a while well if you could determine the stage of gestation then it might give you a better idea that oh I knew that animal is pregnant when I thought she was or whatever so the next diagram I have shows how you do this you measure with a ruler the crown rump length that's called Crown rump length and then they make charts where you can look at look up a chart and say oh that equates to a certain stage of gestation so I found a couple charts couldn't really find a beautiful one that I wanted to like on a dog cat or horse I've got some dog and cat data here and then I'll show you one made for humans so let me orientate you to this table and I just want to point out a couple things crl up here in the top millimeters that stands for crown rump length it must be from some experiments so they've got cats they've got dogs they've got a specimen ID I don't know if they were collecting this data at necropsy or whatever and here's the estimated days of gestation so for the cat and they've got it lined up from small to large and down here they've got data for 40 day gestation of a cat and they're saying at 40 days that's 60 and at 30 it's 26 of course it's going to keep growing and then the dog they've got it at 20 days up to 42 and you can see the crown rump length increases kind of steadily it's not total linear because I'll show you in the human data I have no idea what tissue they're measuring what thickness remember I just grabbed this and I don't know the background here's one that's pretty organized but it's unhuman that well and I shouldn't say but but it's on humans and it brings up this point that there's this identifiable crown rump length the red line shows the mean and then the one thing I like about this is there is a standard deviation this is plus or minus two standard deviations for a certain age of stage of pregnancy this is weeks of pregnancy so to read this down here it's seven weeks three days here's eight weeks four days here's ten weeks four days right eleven weeks plus six days so you can just just see it and it's in the meters but I just want to say there are these tables maybe most of them occur in books and there weren't on the internet I'm not sure well I want to introduce another topic although I did introduce this earlier the uterine involution for every animal there is and our focus animals are horse dog and cat there is basically defined times when the uterus has involuted to the point of being ready for another pregnancy so I found this table or slide from somebody it's about the horse I'm not sure what university this is I'm not sure yeah I don't know anyway normal uterine involution okay so they're saying in the horse by 5 to 15 days that could be considered normal well that seems a little short to me and remember postpartum can a lot of times it's one word but here's what they're saying the onset of the postpartum full Heat day 7 well I didn't talk about this full heat but mares have this kind of funky little physiology where at about seven days after parturition after they give birth some of them will come into heat which is kind of strange kind of early the uterus really isn't ready for another pregnancy but if they're bred a certain small percent will conceive and start another pregnancy so if you hear this term full heat usually about seven days they ovulate and they can become pregnant but the percentage is not nearly as good as if it's later they're saying at about day 14 the uterus is still enlarged so it's not total involution the cervix isn't close you should know that the cervix is like the gatekeeper to the uterus and it had to pass that foal at the time of birth so it takes a little while for it to become closed again but they're saying the endometrium looks normal histologically and noticed the misspelling endo iain do metrium not are ours wrong anyway endometrium looks normal the uterus is still bigger then it's going to be so actually I'm gonna say I'm gonna guess the good involution is maybe 20 to 30 days for the horse anyway I thought that was an interesting slide and here's our list of illustrations that we used see you next time

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