You need to find a veterinarian that knows what this treatment is and who has experience in it and you need to do in advance. You would would surprised at how backwards the thinking is on this topic. Most animal doctors do not know about this treatment, and if they have heard about about, and are willing to do it, they will often do it WRONG, and then call the treatment a failure.This is very important information, I did not want to sterilize it at all. I feel sorry for my dog, like a child for us.
I'm telling you this because if you have an unspayed female, these infections have a high chance of happening. And then what? You will go to one doctor and then another doctor, and they will all say the same thing: "your dog will die, you must operate now." And then you will probably feel pressured to do it.
I've been through this and I learned later on that this is nearly regular practice. So be aware. Know a doctor who knows what to do if this were to happen. Ask about pyometra and prostaglandin injections and what they know or feel about that. Say a good friend warned you about this possibility and you want to know that this service is available and there is experience doing it.
The best is to prevent these infections altogether but I don't know what the answer is. Any food with polyunsaturated fatty acids/seed oils is poison. That I am sure of.