1. Ophthalmology Section; Negah Veterinary Centre; Tehran Iran
2. Department of Clinical Sciences; College of Veterinary Medicine, Islamic Azad University; Karaj Branch; Karaj Alborz Iran
3. Department of Clinical Sciences, Faculty of Specialized Veterinary Sciences, Science and Research Branch; Islamic Azad University; Tehran Iran
4. Department of Veterinary Medicine; University of Cambridge; Madingley Road Cambridge CB3 0ES UK