What is a Retained Placenta?

What is a Retained Placenta?

Tuesdays with Tony

   As I curled up in my usual spot on the seat of Dr. Vurgason’s truck Monday morning, I noticed a distinct, slightly unpleasant, yet oddly familiar odor. It was the scent of placenta. You see, Dr. Vurgason had been out the night before working on removing a retained placenta from a mare that had just given birth to an adorable foal. Curious, and slightly grossed out by the realization of what I was smelling, I started asking Dr. Vurgason all sorts of questions about mares and placentas.  Read on to learn why this is something you need to look out for during the immediate post-partum period.

When is a placenta “retained” and why does it matter?

    In normal mares, the placenta should pass on its own within 3 hours of the birth of the foal. This recommendation is based on the fact that at birth, the placenta begins to disintegrate almost immediately. That’s Springhill Equine Veterinary Clinicbecause the placenta begins to separate from the uterine lining right after birth, and blood flow through the placenta stops. When blood flow stops, a process called autolysis begins. The placenta becomes friable, turns a brownish-green color, and begins to smell quite unpleasant. In short, as soon as the foal is born, the placenta starts to die. Unfortunately, when you leave a dead, decaying, fluid-filled pile of placenta sitting in the uterus for several hours, you end up with a nasty infection.
   The mare’s post-partum uterus is basically a giant open wound. During this time, there is great opportunity for an infection within the uterus to enter the bloodstream and spread throughout the body. This is called septicemia, or sepsis. And, since horses will be horses, guess what septicemia leads to? You guessed it: laminitis. For this reason, mares with retained placentas will often be treated with broad-spectrum antibiotics, anti-inflammatory medications, and will need to wear ice boots until the threat of laminitis has passed.

Why does this happen?

   During a normal delivery, the weight of the foal will begin to pull on the placenta as the foal is born. The umbilical cord attaches to the foal on one end and to the placenta on the other. When the mare stands and the cord breaks, it also gives a good tug on the placenta at the same time. A normal delivery also includes uterine contractions after the foal is born in order to expel the rest of the placenta. This passing of the after-birth is actually considered Stage 3 of labor.
    A retained placenta usually happens for one of 2 reasons: either the mare’s uterus doesn’t contract enough, or it contracts too much. If the uterus doesn’t contract enough, or the uterine contractions aren’t strong enough to expel the heavy, blood-filled placenta, it will just sit there indefinitely. The other possibility is that the uterus contracted too much, and in the wrong places. A mare’s uterus is essentially Y-shaped. One arm of the Y would have been the pregnant horn of the uterus. The pregnant horn of the placenta is thin, stretched out, and covers a large surface area. The other arm of the Y would have been the non-pregnant horn of the uterus. The non-pregnant horn of the placenta is thick, narrow, and covers a relatively small surface area. Fun fact: the most common piece of placenta to be retained is the tip of the non-pregnant horn. Too much uterine contraction can actually cause the uterus to grab hold of the thick, narrow non-pregnant horn of the placenta, and refuse to let it go! You see, the attachment between the placenta and the uterus is kind of like Velcro. There are thousands of microscopic, finger-like projections called microvilli that hold the two layers together. Prolonged uterine contractions can in fact cause these microvilli to get stuck within the uterine lining, like a Chinese finger trap.

How do you get a retained placenta out? 

   I’m so glad you asked, because the technique I’m going to tell you about is super awesome! First of all, the one thing you DON’T want to do is pull on the placenta. In addition, nothing heavier than the weight of the placenta itself should ever be tied to the end of the hanging-out bits. Putting too much traction on the placenta can cause tearing, which leaves fragments of the placenta stuck inside. Even worse, pulling on the placenta can cause uterine prolapse or uterine artery tears, which are definitely life-threatening.
   The first thing to try is a single dose of oxytocin. Oxytocin induces strong, rhythmic uterine contractions for a short duration, aimed at pushing the placenta out from within. This takes care of those placentas that are retained because of the first scenario described above: the uterus didn’t contract enough. I’d say about 50% of the time, this works. The mare says, “oh yeah, I forgot about that part!” And out it plops. However, often when the mare has failed to pass her placenta after we gave her 3 hours to do so, there is a reason for it.
   So the next step is to call our docs, of course. But you already knew that. One of the methods they might employ to get that stubborn placenta out of there is called the Dutch Technique. In this procedure, the vet makes a small incision in the umbilical vein, just above where it broke away from the foal. Then, a tube is inserted into the vein headed toward the stuck placenta. The other end of this tube is attached to a water hose or pump, and water is steadily pumped into the blood vessel. What this does is distend the vessels throughout the placenta, causing it to separate from the lining of the uterus. After infusing several liters of water, we patiently wait 5 minutes. This part is hard…cats are not particularly patient. After 5 minutes, gentle traction is applied to the placenta. Then, if all goes well, out it plops! It is seriously the coolest thing to watch, trust me.
    Well, I hope you learned something from this wise old cat today! Now remember folks, don’t try this at home. Just call one of my docs the moment you suspect there may be a problem.
Until next week,
Tony

Tuesdays with Tony is the official blog of Tony the Office Cat at Springhill Equine Veterinary Clinic in Newberry, Florida. For more information, please call us at (352) 472-1620, visit our website at SpringhillEquine.com, or follow us on Facebook!

Subscribe to Whinny's Wisdoms

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Foaling and Due Dates

Foaling and Due Dates

Tuesdays with Tony

Foaling and Due Dates

We had a foal on Monday. The humans went all gaga over it. I was more like, “Hey, can a cat get some attention over here?” I guess she’s cute. There is some debate over what color she is. Even odds right now on buckskin vs. bay. What’s really exciting about this foal is that she’s finally here. May, the mom,  went 378 days from ovulation to foaling. That’s way over the normal gestation of 340 days, but mares are mares and will do what they please, including ignoring due dates. And on that note, let’s talk about why it was okay that May went 378 days, and why that’s often better than foaling too soon.

Let’s talk placentas

Horses have what’s known as diffuse placentation. When you look at a horse placenta, it looks almost like velvet (red, gooey velvet, but velvety nonetheless). That velvet forms a connection at a microscopic level with mom’s blood vessels. Humans do sort of the same thing, but only in one spot on the placenta. Cows make these connections in a bunch of big knots called cotyledons. This matters because horses need every bit of the placental connection they’ve got to grow that big ol’ foal in there. It’s why twins in horses are usually a bad idea. Where the twins touch, there’s no connection to mom, which means not enough nutrition to grow into a healthy, happy foal.

When placentas go bad

It goes without saying (but I’m going to say it anyway) that bacteria in the uterus with a baby is bad. The cervix does its part to keep the outside out, and the immune system works hard to keep things from the blood stream out of the placenta. However, life being what it is, sometimes stuff happens. In this case that thing is called placentitis. Placentitis occurs when bacteria get into a pregnant uterus and start attacking the placenta. The most common place for this to happen is at the cervix. In some ways, that’s a good thing.

My Docs recommend ultrasound exams throughout those long 11 months (or sometimes 12 months +) of pregnancy. One of the things they are evaluating is the placenta at the cervix. They know it should normally measure less than 1cm and should be tight against the cervix. If they see anything even a little bit off they can start treatment right away. My Docs ultrasounded May at 5, 7, and 9 months gestation and everything was good, so placentitis was unlikely. To be fair, May got ultrasounded a few more times when she started going past her due date, but that’s because the Docs wanted to be doubly and triply sure. And who doesn’t get a little antsy waiting 378 days for a foal???

Uh Oh! There’s an udder!

To be honest though, the Docs weren’t worried about May because her udder wasn’t growing. The udder is an excellent way to tell how the foal/uterus/placenta are doing. Udders should start developing around Day 330 of gestation. If the udder is growing any sooner than that, Call My Docs IMMEDIATELY. Was I clear enough there? Milk coming in before day 330 is not good!!!

May’s udder showed absolutely no changes until about 10 days ago. It then grew at glacial speeds, despite twice daily checks from the techs, Docs, and everyone else around here. (Glacial means really, really slow, for all you native Floridians who avoid all things cold-weather related.)

Antibiotics to the rescue

It’s 290 days of gestation for your mare, every check-up until now has been normal, but suddenly this morning she has a huge udder and you can express milk. My Docs ultrasound her and find some separation of the placenta at the cervix. What now? Antibiotics! And Regumate, and Banamine. But mostly antibiotics. The good news about placentitis is we can generally get it treated with SMZ antibiotics. A little Regumate is added in to quiet the uterus down, and Banamine reduces inflammation. The sooner placentitis is caught, the better the chances things will go well.

May’s placenta was normal, her cervix was tight, and she had no udder. That means no placentitis. My Docs did a couple extra things to make sure everything was OK in there. They did a serum amyloid A test. This looks for inflammation from infection. May’s was normal. They also used the ultrasound from outside that enormous belly to be sure the foal was moving. She was. That left my impatient humans with sitting and waiting. Which they did very, very reluctantly. Lo and behold, we had milk early on Monday morning with a pH of 6.2 (read here about why that’s important), and later in the morning we had a bouncing baby girl!

foal due date

Can’t you induce like they do in humans?

NO!! is the definitive, emphatic answer. Foals develop their lungs in the last 36 hours of gestation. We don’t have a way to know when that is. Take May as an example: if she had been induced at day 340 of gestation (her technical due date), her baby would have still needed 36 days more for her lungs to mature. I may be a cat, but I’m guessing no lungs doesn’t go well with the outside world.

As I said earlier, mares are mares and they will do as they please. It’s a philosophy I can really get behind. Got questions about your mare or due dates? Want to breed? Go check out my blog page for tons of wisdom. Want the wisdom every week? Scroll down a little farther and subscribe to my blog. So easy, even a human can do it!

Until next week,

~ Tony

Tuesdays with Tony is the official blog of Tony the Office Cat at Springhill Equine Veterinary Clinic in Newberry, Florida. For more information, please call us at (352) 472-1620, visit our website at SpringhillEquine.com, or follow us on Facebook!

Subscribe to Whinny's Wisdoms

Enter your email address to subscribe to this blog and receive notifications of new posts by email.