1. Department of Pharmacology, Physiology and Chemistry, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria
2. Department of Microbiology, Infectious and Parasitic Diseases, Section of Microbiology, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria
3. Department of Veterinary Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands