Tumor on hairless rat?

[Phineasand ferb]

I had my boys out for free range this morning and saw a large mass on Doof's stomach. I am not sure if it is a tumor or if it is some sort of infection from a bite. He seems to have been chewing on it as well. I have a few vets in my area that I am thinking about calling tomorrow to see if they have any advice, but I wanted to post the picture of the mass on here to see if you guys have any advice as well.

 

[Kye]

That looks like an abscess... You can use a warm washcloth and hold it there for a few minutes to encourage it to come to a head and drain

 

[Phineasand ferb]

That looks like an abscess... You can use a warm washcloth and hold it there for a few minutes to encourage it to come to a head and drain

Thank you!