I'm sure you've all seen a zillion or more "spay your dog or cat" adverts and PSAs. Most of those focus on pet overpopulation and the fact that millions of adorable kitties are killed annually in shelters and rescues. Some rescue, right? But you can only find homes for so many cats before every one of us becomes a hoarder. This is a totally valid issue, but it's not the one I'm here to rant about today.
I'm setting aside population health issues, and talking about the potential risks to the individual dog of retaining her reproductive bits.
A very brief run-down of the negatives of spaying:
1: they get fat. This is actually not even true - with the exception of medical conditions like thyroid disease, pets get fat because they eat too much and don't exercise enough, not because of a lack of ovaries. Now, desexed animals often have a lower metabolic demand, because they are not roaming around looking for a mate, and both pregnancy and lactation are high-energy activities, but really, if you feed your critter for her actual need, she will not get fat.
2: they won't be as good a guard dog/hunter/sheep herder/whatever. Really? you really think that border collie is herding sheep because her ovaries are rooting her on? NO. Just... no. Dogs hunt, guard, herd, work in general because that's what they are bred and trained to do. A hunting dog's "bird drive" isn't because they wanna get it on and make beautiful 'Labrapheasant' babies.
3: no babies. Clearly this is a problem if you actually plan on breeding. But it's only a problem until you're done breeding, at which point the dog should be spayed.
4: anesthetic. obviously, they have to be knocked out for us to go on an ovary hunt. There is a very small risk that any given dog will have a bad reaction to anesthesia. We can minimize this by spaying young, healthy dogs instead of waiting until they are ill, by doing blood work to evaluate liver and kidney function prior to anesthesia, and by placing an IV catheter so we have instant access to a vein for medication administration if needed. While this risk does exist, you actually have a higher risk that you'll get in a car crash on the way to the clinic than that the pet will crash under anesthesia.
A very brief run-down of the benefits of spaying:
1: no accidental babies. Clearly, if you have no ovaries, you have no eggs, and you make no babies.
2: no heat behaviors. Dogs cycle twice yearly, usually in spring and fall. Cats will cycle every few weeks throughout the spring and summer until they get preggers. ALL spring and summer. Constantly. Yowling, rolling, rubbing on everyone, bolting for doors, destroying window screens, and all the while, all the neighborhood boys are hanging in your yard or on your porch, peeing on all your stuff, fighting outside your bedroom window in the middle of the night, and generally making nuisances of their sex drives. Dogs are not usually so bad, but they have been known to roam over 5 miles from home looking for a date.
3: decreased injuries. See above roaming - dogs or cats that are out and about are much more likely to be hit by cars, kicked by horses, attacked by other dogs or cats, eaten by coyotes, or shot by annoyed neighbors.
4: no ovarian or uterine cancer. If you have no reproductive tract, you can get no cancers of the reproductive tract.
5: no ovarian cysts. See 4.
6: decreased mammary cancer rate. This one's a bit situational, in that it depends on the age of spay; spay before first heat, you get a 90%+ reduction in the risk of mammary tumors as an adult. Spay after the first heat but before the 3rd, and you still get a 50% reduction in risk. The older the animal gets, the less risk reduction you get, until spaying after diagnosis of mammary cancer, which gives no change at all in the risk of developing additional tumors. Mammary tumors are hormonally influenced in a big way, and the more heat cycles the animal goes through, the more chance they will develop them. This is an extremely common tumor in intact female dogs, but only moderately common in cats, so this is mostly a dog benefit. That said, my own cat died of metastasized mammary cancer a short while ago (she was a rescue with kittens when I got her, and was spayed as soon as she weaned, but..)
7: no pyometra. This is actually the one I want to talk about, because this is probably the most common killer of older intact female dogs that I see, and NOBODY seems to know about it until it happens.
Pyometra is an infection of the uterus. It literally means pus-uterus, and that is a very appropriate name. You are all passingly familiar with abscesses, right? Those lovely pockets of tissue that fill with slimy, rank, yellow-green pus and won't heal until they've been drained and flushed and treated with antibiotics? now imagine that INSIDE YOUR UTERUS. Where's it gonna rupture, if it ruptures? That's right - into your abdomen. What's gonna happen then? That's right, you die a horrible death of peritonitis and systemic infection.
How does pyometra happen? Well, every time a dog goes through a heat cycle, the cervix opens up to allow semen entry should the dog breed. Every time a dog goes through a heat cycle, the tissue of the uterine wall swells up, primes itself to grow little feti, and basically makes itself as welcoming as possible. Every time the dog doesn't get pregnant, all that tissue has to be sloughed or resorbed, which leaves permanent changes in the uterine wall, so that the more heat cycles a dog experiences, the more risk of bacterial invasion through an open cervix, and the more likely said bacteria is to grow should it enter the uterus.
What do you see if your dog has pyometra? At first, maybe nothing more specific than lethargy and decreased appetite, probably a fever (but how often do you take your dog's temperature?) This is because the cervix probably closed again after the heat cycle ended, trapping the bacteria and accumulating fluids and pus inside the uterus. Usually, dogs will start vomiting and show increased thirst and urination after a few days. But not always. Sometimes they just die. Sometimes people ignore the vomiting, assuming the dog ate something inappropriate. Sometimes the dog dies after a couple of days of vomiting. If the dog is lucky, the cervix will re-open, and allow some of that pus to start draining out through the vagina. This relieves the pressure in the uterus, making immediate rupture less likely (not impossible!) and also making a huge, stinky, sticky mess of the dog, which most owners will notice. This is the point when I typically see these dogs. But not always... sadly, on at least 3 occasions that I can immediately recall, even this did not prompt the owners to bring the dog to the clinic. Of those 3 cases, all 3 dogs were presented after weeks of progressive illness, and all 3 are dead.
At any point in this spectrum, the treatment of choice is immediate hysterectomy and antibiotics. Take the uterus out, and get rid of the nasty. Antibiotics alone will almost certainly NOT work. Remember, the uterus is now a big balloon of pus and bacteria - a couple weeks of antibiotics might make the dog feel better for a little while, but won't get rid of that crap. How much pus do you think fits in a sac-organ intended to hold 6-10 babies? I think my personal record for pyometra spay is 7 pounds of pus. SEVEN FUCKING POUNDS OF PUS. To put that in perspective, a gallon of water weighs 8 pounds. THAT dog actually lived, by the way.
Now, in case you're trying to educate someone who doesn't empathize enough with their dog to care about the risk of horrible death and the stress and discomfort of illness, try some financial info on for size. Prices will obviously vary depending on area and clinic, but at my clinic, to spay a medium-sized dog as a routine procedure, including placing a catheter and running fluids, and doing blood work prior to surgery, you'd be looking at $225. If you opt out of blood work and catheter, you'll be about $135. Think that's too much? For emergency hysterectomy for a pyometra, on the other hand, you're going to be $600-$800 for the same size dog. How's THAT bill sit with your pocket book? AND, the longer you delay in getting the dog treated, the higher the chances that you'll be handed a $600+ bill and still have to bury the dog. So preemptive spaying really is the cheap option.
TL;DR? There is absolutely no reason to not spay your dog as soon as you decide you're not breeding her. Whether that means you spay at 6 months and never breed at all, or you spay her the day she weans her last litter, I don't care - but I will firmly and loudly tell every single person that asks that the best choice, assuming you like your dog and like your pocket book, is to spay AS SOON AS YOU KNOW that you are done with pups. Stop procrastinating, there is no benefit in delay.