This disease is a little complicated. It can be caused by many different drugs and chemicals or if the white blood cells fail to recognize the red blood cells and as a result the WBC attack and break the RBC's and or the platelets. This is very uncommon to be caused by antibiotics, but penicillins is one of the potential causes. This disease can quickly be fatal if not recognized and treated immediately. The last case I saw like this was caused by a chemical used to treat the lawn. It sounds like your vet did a very good job!! Dr. Weiss 301-299-4142 [log in to unmask] [Posted in FML issue 1117]