What is the mucous membrane colour and what is the CRT and does it fill promptly and vigorously? The CRT is an excellent and objective indicator of perfusion status (it’ blood supply is the same as the brain!). Many books will tell you that a normal CRT is 1-2 seconds. I beg to differ! Most dogs in an emergency clinic will have a CRT or 1 to 1½ seconds. 2 seconds is too long. Also remember that fast (<1 second) is abnormal too. You should also note the vigour with which it fills: is it normal, reduced or increased? And lastly, remember that normal cats have paler mms than dogs and that some normal dogs have redder mms than others (eg liver Dobeys or staffy/pit bulls). This video is of a 100% normal dog. What do you think of his CRT?