thank you in advance.
Get an appointment at a cavy knowledgeable veterinarian asap.
It got to this size suddenly, but before when he sat it looked like he was just resting his weight on his right side ? From its location I used to think it was just his thigh muscle and not an abnormal lump, if that makes sense. (when it was much smaller) I'll definitely take him to the vet as soon as possible though I'm worried about the outcome of surgery, having read some negative stories about owners with similar experiences. Guinea pigs being so fragile and all, I worry about something going wrong. Luckily Leo has always been a healthy cavy.
i'll keep you updated
The vet said it was a mammary tumor. While it could be removed with surgery, the cancer would remain and spread anyways. I didn't want to euthanize him at first but since the tumor had grown so much in such a short time (2 days ago I noticed it this size) it would only get worse. Eventually he would not be able to walk with the size of the tumor. When we checked his abdomen his right nipple was black, which is another sign of mammary tumors.
The lump was already spreading to his leg and when the vet pricked the tumor there was only blood. He said that for him to still be alive with a tumor that size Leo had to be very strong. And he was, even with the sedative before the actual euthanasia he was trying to move and he took a long time to sleep
A sebaceous cyst is supposed to be filled with keratin material, not blood right?