How can you effectively provide relief to a rabbit in a heatwave?

Rubbing ice on a rabbit's ears is an effective method for providing relief during a heatwave because a rabbit's ears are highly vascularized and play a crucial role in thermoregulation. The blood vessels in the ears have the ability to dissipate heat, making them an excellent target for cooling. When ice or a cold compress is applied to the ears, it can help lower the rabbit's overall body temperature more effectively.

The other options may not be as safe or effective. Simply increasing food intake can add to the rabbit's digestive heat load, which is not advisable during excessive heat. Wetting their fur could lead to potential problems such as chilling or skin issues if the fur does not dry properly, while using a cooler full of ice poses risks, such as frostbite or stress from extreme temperatures.