Swollen incision area

Question
Hi. About a week ago, I took three rats to have mammary tumors removed (two were mine, and one was my friend's). Just the other day I noticed some swelling at the site of the incision on one of my girls, and my friend said his rat has the same thing. We're not sure if it's just an infection or what is going on! The vet who did the surgery is about an hour away, and with our school and work schedules, it's going to be a little tricky to get them both down there again. The swelling has reached a size that is similar to or bigger than the size that the tumor was. I don't know if tumors can regrow that fast, or what is going on. My other girl does not have this issue. We both have antibiotics on-hand, and I gave my girl a small dose of Baytril last night (about .1 cc) just in case. In my girl, the swelling has not gotten any bigger since yesterday, and I cleaned my "hospital" cage really well and wiped both girls down with a baby wipe, just to clean them up a little bit. We are planning to get them to a vet as soon as possible, we just want to know what might be causing this.

Answer

Sounds like one of two things:  The girls have either a seroma or a hematoma, both are common (and often minor) normal response  after surgery.

The rats body is reacting to an empty space within the tissue that was previously attached to something.  When a mass is removed, damage occurs to the very small vessels that sometimes cause escape of serum into the empty space,which would be the space where the tumor was. This serum is what makes up the seroma,which is a pocket of clear serous fluid that sometimes develops in the body after surgery.


A Hematoma is basically bleeding into the surrounding tissues where the surgical site is, also filling up the empty space. Sometimes a hematoma happens because there are small blood vessels that break after surgery. These blood vessels normally should have been retracted  and tied during surgery but some Vets may miss them, esp when dealing with a tiny animal. This is why the vet should have the proper lighting and instruments to work with so he can always see these vessels and tie them off to prevent internal bleeding.

Both a seroma and hematoma usually reabsorb back into the body, but its best to drain them and even  put the rat on antibiotics (that should be done in the first place anyhow) to prevent infection.

Sometimes draining it is not really the cure since its back to the "empty space" again and this means it may fill up again.  Its better for it to absorb naturally but you can also help by doing something, providing the rat allows it, which would be to apply a heated compress to the seroma.  This will reduce swelling by increasing circulation to the area. The fluid in the seroma should reabsorb faster this way.
For both the seroma or hematoma (depending on which one it is the rat has)You can use a warm, moist washcloth and try your best to apply to the area for 10 minutes, even 15 if possible.  laying the rat across the warm cloth and pet her to keep her busy may help to keep her still longer.

Be sure to call the vet tomorrow and let him know what is going on and also let him know that your using heat (if that is what you decide to do)

Hope this helps!