Besides revising the antimicrobial and species chapters, new chapters will be added: 1. Pharmacodynamics of antimicrobial drug agents 2. Macrolides, azalides and streptogramins 3. Prophylactic use of antimicrobials (new to chapter 21) 4. Regional and intraosseous perfusion (new to chapter 22) 5. Infection of the respiratory system (new to chapter 22) 6. Anaplasma/Ehrlichia//Neoriketsia (new to chapter 23) 7. Antimicrobial use in new world camelids (new to chapter 32)