So have taken an almost 12 yr old Rottie bitch to the vet's today, with a prolonged season (never happened before). No sign of being unwell, no pus, just minuscule amount of blood. After an ultrasound vet has diagnosed open pyometra, gave an option of spay, or antibiotics. Because of her age, I elected for antibiotics, but am undecided if that was the right option. Will an open pyyo resolve? Will it turn into a closed pyyo, and become an emergency? Just need people to comment, and help me make my mind up, love this girlie to bits lost her brother last July, then a year younger sister, and a home bred 19 yr old horse both with liver tumour!!!!!!

I had a 13 1/2 year old spayed just before Xmas, she'd developed a vaginal polyp which was hormone related.  When spaying her, she ad an open Pyo. 
This polyp was likely to return on each season, so we decided to go ahead with the op. 
I was very worried as it was so close to Xmas with minimal veterinary cover but she made an amazing recovery and is now a much happier and lively girl.  We don't know how they are feeling but I am very glad I went ahead with the op.
I am not normally in favour of spaying but will now spay my girl before they get too old and the risks of surgery increase.
Hope your girl responds well to the AB's

Pyo will almost certainly recur next season, so I would wait until she is midway through and get her spayed when she is well.

I spay all mine after their last litter to avoid this scenario when they are older and unwell.

We had a bitch with pyometra. It's the scariest thing I have encountered with my dogs, to all intents and purposes she was fine but with just a slightly funny whiff when she wee'd. Took her into the vets to discover pyometra and she was operated on that day. Vet said if we'd left it another day we'd have lost her. As it was a Friday and Christmas was the following Monday/Tuesday I dread to think what would have happened. I hope the antibiotics work for you, but be alert as they can go downhill very fast.

At 12 years old, and with todays wonderful anaesthetics I would 100% go for a spay.  Better done now before she goes downhill.  I have all my bitches spayed after breeding for just this problem.