The former Charmed star first raised concerns about Diesel earlier this month (Jan13) and took to her Twitter.com blog to ask fans for their prayers.
She tweeted, "My dog Diesel is sick. They think it could be liver failure. Please keep him in your prayers. (Thank you.)"
The poor pooch underwent a series of tests at the vet's office and the results are not good.
Updating fans with the sad news on Friday (25Jan13), Milano writes, "My Diesel has cancer. I'm heartbroken."
