Ear temperature

• A house cat's ears can feel warmer or colder than the rest of its body. Before calling a veterinarian, observe the animal.
  
  

Anything different?

• Look for abnormal behavior. If the cat is not eating, playing or acting as it usually does, there may be something else at work. Other symptoms include a runny nose, matted eyes, coughing, sneezing or changes in litter-box usage.
  
  

Yes, There Are Changes

• If there are changes in behavior as described above and in addition to a change in ear temperature, taking the cat to the veterinarian, or at least calling the veterinarian, is a good idea.
  
  

External Factors

• If the cat is otherwise acting completely normal, the warming or cooling of ears can simply be a result of changes in blood circulation. The change could come from lying near a warm heater or a warm human body, or from sleeping on one ear. An ear could be cooler from sitting next to cool air coming in through an open window. Any of these things could cause changes in body temperature, just as it might in humans. The cat's ears are more exposed, and so will reflect body temperature changes before other parts of the cat's body.
  
  

Bottom Line

• Unless other symptoms are present, cold or hot ears on a cat are usually just a normal change in body temperature, and not a reason for worry.