Weather here is so much hot, about 92 °F. My rabbit is breathing very fast. He eats well and his removals are quite good, but he breathes very fast whole day, so what should I do with him to make him relaxed? Should he bath everyday? Please help me, it's urgent!
Provide your rabbit with ways to cool down. He should always have water and shade available. Include some high water content veggies like plenty of greens and small amounts of cucumber with his food.
You can also provide air flow, such as fan. Ideally this should be placed so the strong air current will not blow directly on the bunny, or at least so he has the choice to get out of the air flow to give him control over the degree of cooling.
Rabbits can easily suffer from heat exhaustion, and in an extreme emergency situation this can be treated by quickly cooling the rabbit with a slightly cool bath, but you should not rely on regular bathing; it is far too stressful for a rabbit, and they are prone to become ill when washed frequently. If the water is too cold, it can even induce shock and kill a rabbit!
An easy and safe way to provide cool comfort for a rabbit is to place ice where your rabbit can lay or lean against it. A frozen bottle of water (2-liter soda bottle works well) is less messy than ice cubes or packs. Avoid using any commercial ice packs that contain some 'gel' or colored liquids unless under your supervision. Although non-toxic for the most part, it's not healthy for your rabbit to eat or chew these.
You can also make a large ice block with some veggies frozen in it for your rabbit to nibble on, or provide some ice cubes to lick or in their water. If you are using ice while your rabbit is in the hutch/cage, there should be enough space for the rabbit to get away from the ice if he wishes. Choose a place for the ice where any leaking water can drain away and not soak the bunny or his bedding. If melting ice or condensation makes the bedding wet, you may have to change it more often-- Mold can grow quickly in hot weather and is a health hazard.
Finally, you can slightly wet the rabbit's ears to provide evaporative cooling. Just run your hands under water and stroke his ears. You can experiment with a light spritz from a spray bottle, but your rabbit may not like this. Don't pour or splash water on a bunny's ears, as it should not enter the ear canal. You can moisten the paws as well if your rabbit allows it, but avoid this if seems stressful.
Finally, make sure you watch for signs of heat stroke, like red ears, panting, drooling, trembling and lethargy. If you note these signs, act quickly to cool your rabbit, and seek veterinarian treatment as needed, but don't overdo this and 'shock' the rabbit (for example, don't place the rabbit in cold water or pack him in ice).
For more detail about heat stroke and ways to help rabbits keep cool, this is a useful article.