I am grateful for the constructive suggestions I have received from students, readers, and colleagues for the firrst edition of Handbook of Veterinary Pharmacology. I want to thank Professor Fahd Z. Eissa especially for his thorough review of the book and comments. In response to these suggestions, and in light of the many important changes that have occurred across the landscape of veterinary pharmacology and therapeutics over the past five years, we have made a number of significant improvements in the second edition of the book. I hope and expect that the following additions will aid students and faculty in the learning and teaching of veterinary pharmacology:

* Thanks to the contribution by Dr. Brett A. Sponseller and Dr. Beatrice T. Sponseller, a chapter on immunostimulants and immunomodulators (Chapter 8) has been added to the book.

* We expand the concept of P-glycoprotein in the drug eux mechanism for many drugs in Chapter 1. There is more and more appreciation of the P-glycoprotein in pumping out an

array of chemicals across the cell membranes of the organisms. Interestingly, this protein is also involved in the development of drug resistance by microorganisms.

* Comprehensive updating of all chapters and appendices (withdrawal time charts and dosage table) including new drugs approved by the FDA through 2012 and drugs that are frequently used in other parts of the world but not in the U.S.

* Comprehensive updating of many gures and tables with addition of 23 gures over the rst edition of the book (from 60 gures in the rst edition to 83 gures in the second edition).

* Creation of the chapter outline with page number listed for each subject heading.