My baby rat has a lump under her neck.

Question
Hello! I have a ten week old baby female rat and I just recently found a lump under her neck. I got her about two weeks ago from a breeder, along with her sister. They have un-colored carefresh bedding and I clean their cage every two weeks with a non-toxic sanitizer so it won't bother them. I feed them rat lab blocks which I've read are very healthy and I only give them filtered water. I take them out to play from their cage everyday and occasionally give them treats like yogurt, fruits, veggies, all in moderation. The lump isn't big, it's about a little under the size of a pea and it hasn't really seemed to grow any in the last week. She is still very playful and eating normally and when I touch the lump it doesn't bother her. Also the lump can be moved around inside her and there isn't a scab or anything over it. She's a siamese dumbo rex and super adorable, and I'm just really worried because this is my first time owning rats. I'm just wondering if it might be a tumor or and abscess or cyst or something? It's right under the skin. I plan on taking her to the vet if it gets any bigger or seems to bother her, but any help from you would be really appreciated. :)

Answer
I would be really shocked if this is a mammary tumor, esp at her age.  I am thinking it is either a cyst or an abscess.  You can try to get it to a head if its an abscess by holding a warm compress on it, providing she sits still.  If it is a tumor it can be easily removed and in fact this would be an ideal time to spay her as well in order to prevent growth of mammary tumors in the future.  If this turns out to be a tumor please be sure to let the breeder know so they can document this.  Again, I cant say for sure, but I would be shocked if it is a mammary tumor.

Be sure your vet is a qualified enough to treat your rat. many vets will say they see pocket pets but they truly are far from qualified and only know the basics on rat care. Your better off with a vet that is either an exotic companion mammal specialist or a Vet that has pursued exotics as a special interest.  A vet that simply will see pocket pets along with dogs and cats may not have the skill to perform the surgery and the sad thing is, many are too arrogant to admit it and this will risk the well being of your rat.