A quick google kicks back "abnormally enlarged blood cell" for macrocytic, which of course it is, now that I look at the word. Agglutination also makes it sound like her blood is thickened, due to either high globulin (a protein found in blood) or dehydration. I imagine the saline test would be simply that they rehydrate her with saline for a bit and test again for agglutination. An erythrocyte is a red blood cell. So.

What they're saying is that she has abnormally enlarged red blood cells, and this, along with the non-regenerative aspect, is primarily a sign of FeLV in cats. It may also be [insert list here] but it's usually FeLV. If the anemia continues non-regenerative, they need to do a bone marriow asperate and biopsy. The ELISA is apparently a bone marrow test, which I imagine will conclusively determine whether it's FeLV or FIV.

Shit.