Shana was peeing and drinking a lot too. She was having accidents in the house as well, so we got on the phone with the vet. She was diagnosed with a probable urinary tract infection, and that was to be treated and look for improvement. She really did not improve from her lethargy and looked very uncomfortable. In the meantime, I had asked an unrelated question on her breeder's page about mammary tumors, and someone mentioned the danger of pyrometra. This is an extremely dangerous infection of the uterus of different types of animals, including dogs. It is likely to happen to 25% of intact female dogs right after a heat. At this point, I was obsessed with this, and called our vet to update on the progress, lack there of, and what was currently happening.
At the next vet exam, it was explained that she had pyrometra and emergency spay was the solution. They could not get her in that night, but her cervix was open so it could be safely done first thing in the morning. That morning was yesterday morning, and Shana came out without any complications and is now resting comfortably. In doing searches for pros and cons of spaying your female, I came across some that mentioned this now, but not many articles do mention this. On my breeders page, others in the conversation also confirmed that not many people know of this danger. I suspect because I was busy with the dogs I was training, I did not see the signs of lethargy sooner until I had stopped for our vacation. We were extremely lucky to have known our dog and to have caught this. At the beginning though, I thought I may have been overreacting due to the fact that it has been very hot in Maine, Shana is not a super hero although she has always been a force of nature, and I may have just (in my mind) been expecting her to want to be much more active then she wanted to be.
Our current veterinarian very recently (before COVID 19) just recently became our vet, so I never had that conversation with him, regarding spaying or not. Most (not all) veterinarians will assume you can't keep your female dog safe from wandering and getting pregnant in heat, so I probably assumed when Shana was a puppy that is what the answer would be. This is one of those things, you just hope you never have to get familiar with, especially in an emergency situation. Be safe and always ask questions when it comes to your dog's health.