1. Josepha DeLay Animal Health Laboratory, University of Guelph

2. History 200+ ewe flock acute onset neurologic signs confined to 1 pen of 8 month old lambs 17 / 40 affected over a 10 day period 2 / 17 dead (1 necropsied), 4 additional affected lambs euthanized and necropsied

3. Clinical findings Clinical signs: Depressed Anorexic Blind Head / body tremors, weakness, hindlimb ataxia Differential diagnoses: polioencephalomalacia, listeriosis Initial therapy: thiamine, tetracycline – no response

6. bar 50 um bar 10 um Brain (medulla oblongata), lamb C Brain (midbrain), lamb B Sarcocystis spp IHC (cerebellum)

7. Skeletal muscle, lamb B Myocardium, lamb C Sarcocystis spp IHC (myocardium)

8. from M.Jeffrey, 1993, In Practice, 15: 2-8.

10. Additional history New guardian dogs purchased ~2 months prior to onset of neurologic disease in flock Dogs were acclimatized to sheep by housing in sheep barn, with access to feed bunk area of pen housing affected sheep

11. Outcome: 3 treatment groups based on pathology diagnosis Amprolium Toltrazuril No treatment Improvement in mental status and appetite regardless of treatment No additional sick lambs or deaths in 2 months following initial outbreak

12. Thank you to OVC collaborators on this case: Dr. Andrew Peregrine Dr. Paula Menzies Dr. Jonathan Huska Dr. Luis Gaitero