Followup on pyometra (pyometria, metritis)

Because I wanted to make sure all my ducks were in a row before I tried to explain why leaving bitches unbred risks pyometra, I spent some time online last night looking at Theriogenology (the scientific journal of animal reproduction). And WOW, if anyone would like to get me a really expensive birthday present, a year of that journal (a mere $400, come ON!) would not go amiss. I realize that I am ill in the head zone about stuff like this, but I was up until three a.m. because I kept getting so sidetracked reading articles. I’d do a search on mucometra and there’d be an article on whether mares get pregnant more often in the uterine horn opposite the one in which they had last been pregnant, and whether that was related to the age of the mare, and an hour later I’d surface from some super-key discovery about boar semen count and try to get back to the dog stuff.

And by “stuff” I mean JUNK, baby. You know it. This whole week is going to be all about the euphemisms, geez.

And there you go. I started this post 30 minutes ago and I am just back to it, because I went to the journal to check the spelling of something and there, on the front page, was a discussion of the proper extender to maximize the thaw of HONEY BEE SPERM.


I am now unbelievably frustrated because all I can access is the abstract. And I have some very key questions, questions involving tiny tiny  containers and magnifying glasses and bee porn. And these questions must be answered.

OK, well, ANYWAY. Pyometra.

It’s important to understand that pyometra in the bitch is not something that you did wrong, or she did wrong, or an infection because she was sick, or because she doesn’t have a good immune system, or anything like that. It’s the result of the uterus not being pregnant.

Here’s what happens: Like I talked about in the prior post, the uterus gets the same hormonal bath when the bitch is not pregnant as it would have if she were. This causes a HUGE increase in blood flow, blood vessel growth, and the very particular kind of soft and spongy blood-rich “pillow” inside the uterus that would normally encourage the placentas to get a whole bunch of blood and nourish the puppies.

When there are no placentas, no puppies, the lining of the uterus doesn’t know what to do (to anthropomorphize, but that’s the closest I can come). It wants to interface with a whole bunch of placentas but there are none. This causes it to get, well, bubbly. Instead of being a nice smooth thick pillow, it begins to look like bubble wrap. And each bubble is filled with fluid.

The chance that this will happen increases with each heat cycle. It’s very likely that there’s at least some of it going on by the time the bitch has gone two or three cycles without pregnancy. But with each non-pregnant cycle, the chances that it will go from a little to a LOT increase.

I can’t find an exact number for this, but a whole bunch of bitches who have gone through some empty cycles develop a condition where those cysts in the uterus release a bunch of fluid that begins to fill the uterus. This is not the same as a pyometra; it’s not an infection,  and the bitch doesn’t get sick. The reason I want to highlight it is that it’s tempting to say that well, I’ve never had any of my bitches get pyo, so my girls must be just fine. In fact, they’ve got a lot of nastiness going on in there, but they haven’t been unlucky enough to get an actual raging infection.

Where this cystic condition–again, very very common in bitches and just because you don’t have illness that doesn’t mean it’s not happening–is combined with either bacteria or an irritant, THAT’s when things go very bad.

Most of the time, the cervix (the thickened muscular area that separates the large “vaginal vault” from the uterus) in the bitch is very much closed, and is plugged with thick mucus. It’s absolutely excellent at keeping anything that is not supposed to be inside the uterus OUT.

However, during the bitch’s season, for obvious reasons, the uterus needs to be able to let things IN. So the opening gets a little bigger, and the mucus changes from being thick and sticky to being thin and watery. When she is bred, the semen can move into the uterus without any trouble.

Unfortunately, during this open-cervix time, other stuff can move into the uterus too. The most common is e. coli, which has nothing to do with whether you keep your kennel clean and everything to do with the fact that dogs sit on the ground. There’s almost no way to keep your precious girl’s princess parts from coming in contact with billions of e. coli bacteria. And once they get into the vaginal vault, they can travel into the uterus.

And once they’re there, the uterus goes NUTS. It’s not just that the bacteria grow and cause an infection–they do, but one of the reasons it gets so bad so fast is that the bacteria set up a little irritation and the uterus goes bananas. Researchers have induced full-blown pyometra by putting a tiny irritant like a thread into a cystic uterus–it doesn’t have to be a big bacterial infection to get a giant pyo going. The uterine lining, which is all abnormal and bubble-wrappy at this point, starts producing fluid and pus in a completely overblown way, and in a very short amount of time the uterine horns go from being the size of two drinking straws to being the size of two zucchini, completely filled with pounds of infection.

That infection is what makes bitches with pyo get so sick, so fast. I’ve seen it happen, and the bitches pretty much just collapse. There’s no question about whether it’s severe–they spike a fever, they can barely move.

Once the uterus is in trouble, most vets will just spay the bitch. It’s a big fat scary deal to spay a pyo bitch because of the tremendous size of the uterus and the possibility of spilling the infection. So you’ll be paying through the nose for a major surgery, and plenty of bitches don’t make it through.

Some vets, those who understand that it can be worth it to save the reproductive life of a bitch and who have a bit of a gambler’s tolerance of risk, will try to treat the bitch. This is possible if her cervix has remained open and the infection can be drained. He or she sets up a course of prostaglandins, extremely powerful hormones that cause the uterus to contract strongly. The bitch (in effect) is put in labor over a period of multiple days, and her contractions squeeze the pus and infection out of the uterus.

It works, in a good number of cases, but it is very painful for the bitch and it’s something nobody ever wants to go through. I’m not saying it’s not worth it, but this is not “take two pills and call me in the morning.” It’s an intense and traumatic process for all involved.

And, of course, once it’s over it’s not over. The bitch has a very good possibility of repeating it on the next season, so most vets will strongly advise that she be bred on that season. I am honestly not sure if after that it is ever safe for her to skip a season again–most of the breeders I know who have gone through a pyo treatment have gotten a litter that next season and then spayed her.

Pyometra can occur after any heat cycle, including the first. But, thankfully, it’s very rare until the bitch has had a couple of empty cycles. Personally, I don’t feel comfortable going more than three without fishing or cutting bait on the bitch, and I won’t skip more than one as the bitch gets older.

For example, Clue turns three this spring. She is due to have her fourth heat cycle any minute now. Even before her injury, this summer was going to be our deciding time for her. If she hadn’t finished, she would have been spayed. Since she did finish, we were going to breed her on this cycle. That is not possible, so we’re going to wait through one more, but I am nervous as heck about it and I will be watching her like a hawk.

If she comes through it OK and we can in fact breed her this fall, I’m inclined to do as many breedings as I think she should have (which will not be many) and do them back-to-back, or even back-to-back-to-back, and then spay her. She’s not a bitch I would ever breed over a period of multiple years, or when she’s seven or eight, because of the pelvic injuries. She IS going to get arthritis back there; it would be impossible for her not to. I don’t want any weight on a painful rear. So if I am so incredibly fortunate as to be able to breed her, period, I’m going to be thankful for anything I can get and I’m going to get her retired, on the couch ordering the other dogs around, long before she has any pain.


4 thoughts on “Followup on pyometra (pyometria, metritis)

  1. OMG–you have full online access to Theriogenology (not just access to their abstracts like everyone has)!? It’s one of the few journals the college I work at doesn’t subscribe to so we can’t access it online–there have been a few papers from it I’ve been interested in looking at but I don’t want to pay the $30+ dollars they want per paper.

  2. Ha! No, pockets are not deep here.

    I find the abstracts and then use my google-fu to find the researcher and hopefully the full text, or more of the full text. Google scholar, Amazon searching, way back machine, and the various journal searching engines that “cache” a page have some serious power.

  3. Oh, and Theriogenology’s/Elsevier’s free membership does get you some full-length stuff. Not a ton on dogs, but enough on everything else to keep me going for hours.

    And… I can’t actually say anything about real words or real titles because I have a nondisclosure (as stupid as it may be to have an ND for lowly proofreaders), but there are some perks to being an editor who does medical and textbooks.

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