Help! I found a lump!!

[Marlania]

I was trimming my guinea pigs' nails today, and I found a lump the size of a dime on Permanent's back. It's close to the bottom of her back, above her butt...where she can't reach, luckily, so she can't bite it open. How on earth I didn't see this before, I'll never know. I handle them everyday, but somehow I never noticed it. The lump is soft, but not squishy. I can't get her to my pig doctor because she's out-of-state, so I'll have to take her to the dogs' doctor, who of course won't be open until Monday. (grrr!) Anyway, here's a picture of the lump. I'm thinking some kind of tumor, but I have no idea if its just a fatty mass or not. It'll need a biopsy, I'm sure. She doesn't appear to be in pain and is up to her normal activities. She's approximately 2 years old. This bump does not feel like the tumor that develped on my hamster's spine, which was fairly hard. The only other experience I've had with tumors was a mast cell tumor on my Lab, which was benign and removed. Obviously, this isn't the same. Any ideas??

(It looks bigger on the pics...it's just zoomed in to give you a better look.)

 

[Slap Maxwell]

I could be an abcess or a tumor. You need to get to the vet so they can stick a needle in it and figue out what it is.

If it is painful it is probably an abcess.

EDIT: (it could also be a fatty tumor)

 

[Marlania]

Oh we're definitely going to the vet Monday morning. There's no question about it. This thing needs to be aspirated and checked out.

 

[Slap Maxwell]

Does it hurt him?

 

[luvfamrap]

it said in the post it doesnt seem to be hurting him.

 

[Marlania]

She doesn't appear to be in pain. I poked it a good bit, and she didn't say a peep, or flinch, or anything that would indicate I was hurting her. She's active as usual, eating like the pig that she is, drinking normally, and just being her normal self. It's almost like she has no idea it's there.

 

[Slap Maxwell]

Oh. Then it is probably a fatty tumor.

 

[Marlania]

Will its size go down after its aspirated? I ask because when my dog's mast cell tumor was aspirated (tiny...like the size of a mosquito bite), it went down to nearly nothing before it was removed.