NAVLE（北美执业兽医考题）Day 643

Suzie, a 6-month old female spayed domestic short hair was recently adopted from the humane society. She has had watery diarrhea since adoption. Her fecal float and Giardia ELISA tests were negative. She was treated with metronidazole with no clinical improvement. You soak a cotton tip swab with saline and swab the rectum. You see elongated motile oval shaped protozoan organisms that do not look like Giardia lamblia. What organism might this be and what is the appropriate therapy?