A large, hard abdomen in a spayed cat could be caused by several things, some serious. It's important to get a professional diagnosis to rule out potential problems and get the proper treatment. Here are a few possible causes:
* Abdominal tumors: These can grow to a significant size and cause a hard, swollen abdomen.
* Fluid accumulation: This can be caused by various conditions like heart failure or kidney disease.
* Bloat: This is a life-threatening condition where the stomach twists and becomes trapped, causing severe pain and distension.
* Constipation: Severe constipation can lead to a hard, distended abdomen.
* Urinary tract issues: An infection or obstruction could cause swelling and pain in the lower abdomen.
Please don't hesitate to seek immediate veterinary care for your cat. Early diagnosis and treatment are essential for a positive outcome.