Was diagnostic imaging performed? X-Rays? preferably ultrasound?
What about vaginal swab cytology?
Abdominal palpation and CBC are helpful but not the best methods to diagnose pyometra. If the uterus can be felt on palpation, then I wouldn't consider it "mildly enlarged." Furthermore CBCs can be elevated for many reasons. Also for several reasons, life threatening infections, including pyometra, can be present with a "normal" CBC.
In general, no pyometra is a good antibiotic candidate. They are typically only surgical candidates.
For non-infectious ovarian/uterine problems, false pregnancy or inflammation can be present.
If the pet has not been bred/with a male, then the dog cannot be pregnant. If you are not sure, the best method to evaluate is an ultrasound - not only can you see the fetuses but can also ensure that the puppies are alive. It is also the most straighforward method to look for pyometra.
There are also two types of pyometra - "open" and "closed" pyometra. Open pyometras have an open cervix which allows fluid to drip out. CLosed or partially closed pyometras will have little to no discharge. Thus the amount/frequency/presence of discharge is NOT a good method to evaluate pyometra. In fact, a pyometra with little to no discharge can be MORE dangerous then one that does because the pus has no where to go. Any type of pyometra is considered life threatening.
When pyometra is a concern, you need to get a diagnosis and if the disease is confirmed, then surgery should be performed right away.
I hope that this helps.
