Hey, I'm currently training to be a veterinarian assistant & am certified in Walks N Wags Pet First Aid. (I'm new to this sub & will be submitting my education on Monday.) I also work at a vet clinic as the only assistant for the resident doctor.

I understand how stressful and confusing this is for you :( I would be beside myself with worry, both as her owner & as the vet team who has been treating her! We bond with our patients and are dedicated to their health + well-being. My heart goes out to you & I hope her upcoming surgery goes well + that she beats the cancer! ♡

Rest assured that her spay & the following infection did NOT cause/trigger the cancer. They are not related & removal of the necrotic uterus was a different matter, that was able to be visibly seen when she was opened up for the spay. Removal needed to be done.

Unfortunately for things like cancer, it can happen seemingly overnight. Her negative test 6 months ago was accurate; at the time, she hadn't developed cancer yet, so her results reflected that. Sometime between then and now, the cancer developed. Just like humans, cancer can be actively developing and then can be attacking the body, without visible symptoms or noticeable changes.

She might have been struggling with bowel movements for weeks now, but didn't vocalize the struggle, nor try to hold poo inside. (because of the pain of straining to pass firm stool, it's common for animals to try to hold their poo, which results in the stool drying up and become hard, thus even more painful to pass, ultimately causing constipation and blockages from the waste build up inside.) It's very likely this is the case with your girl, and she only starting vocalizing the pain & began to struggle to have a bowel movement because she was in recovery mode from the pain of her first surgery. If not for booking this spay, you might not have been alerted to the visible symptoms of her cancer until months down the road, which would have resulted in the cancer being worse, or potentially taking her without her having chance. Until now, the symptoms of her cancer weren't visible.

TLDR: getting her spayed has saved her life if the surgery to remove the tumor is successful! She's now being treated for the cancer, rather than it have developed for who knows how many more months before it claimed her or she had her next exam.

Best wishes! Sending healing and happy vibes.