Will Falconer, DVM Moderator
Here's a bit of an exhaustive list of ADE (adverse drug events) from the FDA, and though it likely represents only a small fraction of actual adverse events, I see anemia, death, bleeding disorders, and a plethora of liver and kidney markers that are abnormal (the latter pointing to toxicity issues, my point in this article).
They'd have to do more tests to measure autoimmune issues, but that's likely the cause of anemia and bleeding (thrombocytopenia: low platelets, can no longer clot properly, so bleeding occurs).
Could one dose in dogs, especially a 12 year old, be responsible? I'd be very suspicious, especially if it struck both dogs and was the only apparent variable.
I'm so sorry you're going through this. It's got to be devastating.