If a Vampire sneaks up on a lizard while asleep, the blood should be around it's normal minimum, unless it is basking in the sun. If the drinking is after an extended fight, then the temperature should be close to the maximum possible. This is not likely to be as great as human body temperature in most cases.
Count Guillaume said:The Lizardmen was an example of the situation descibed in the quote, but you can easily take this situation too:
Would a vampire drink from a dead corpse from a day ago, with no other real option?