These are some of my favourite ECC-related resources, ones that I interact with on a regular basis. I have not included any of the journals that I review as not everyone is fortunate enough to have access to these. Links to ECC societies and other more general resources can be found in the Links page.
Small Animal Critical Care Medicine (Saunders) edited by Deb Silverstein DACVECC and Kate Hopper DACVECC
Fluid, Electrolyte and Acid-Base Disorders in Small Animal Practice (Saunders) authored by Stephen P. DiBartola DACVIM
Pilbeam's Mechanical Ventilation: Physiological and Clinical Applications (Elsevier) authored by J Cairo
EM:RAP (subscription must be purchased)