A sure way to keep your buns as cooler - Ventilation is key. Create as many air exchanges as you can. At Blackberry Farm the front louver fan pulls air in and cools it while the back louver blows the warmed air out. Most days this is enough and the rabbitry remains at least 10 degrees cooler than outdoors. The extra insulation in the ceiling, insulated walls and concrete floor all complement the cooling process. With the concrete floor we are also able to hose the floor which cools the air and adds moisture.
When it is super hot like this past week we not only run the front and back fans, located in the louver vents, but THREE other pedestal fans as well. The rabbitry has three aisles, front, middle and back. The first aisle's pedestal fan blows air front to back, the middle aisle has an oscillating fan blowing towards the front, left to right. The last aisle has a fan blowing towards the front. So basically these three additional fans circulate the air around the perimeter in a circle and disperses air left and right down the middle. Yes, Central Maine Power loves me!
Other methods you can use - freeze 2 liter bottles and put them in the cages, especially with litters and nursing or pregnant mothers. Freeze ceramic tiles they can lay on. Hose the roof of your building, this can bring temps down 10 degrees in less than 10 minutes. Put a soaker hose on the roof for longer periods of time. Wet and freeze a towel you can put over the cage or in with the bunny. Just be sure to remove it when it loses it coolness and do not block airflow around the cage. Christmas Tree Shop sells the flat blue icebergs for less than $2.00 each. Although they don't stay frozen as long as the bottles, the bunny can lay down and cool off its underside which it can't easily do with a frozen water bottle.
Most important look for signs of distress, they are:
Wetness around the nose and on the face, severe panting, listlessness, extremely hot ears. A little wetness under the nostrils is normal as they breath out warm air. A wet face is not normal.
When you see a bunny in trouble, act quickly, bring them inside and cool them down. Perhaps you have a cool basement they can live in for a few days or at least during the heat of the day. Wet their ears, put a fan on them. In exteme measures you can dunk them in water, but not ice cold water as the shock is just as bad. Do not dunk their heads, just their bodies.
Try not to handle, groom or pat rabbits during hot spells, this just increases their body temperature and if they are the nervous type will only increase their heart rate and respiration. The latter increases their body temperature when they stress. Always, always have cages out of direct sunlight. Even if all the cage isn't in the sun, the heat on the wire will transfer down thru to the shaded area.
When it is hot, the rabbits won't eat as much during the day, so don't panic. They will eat more at night. Clean litter pans more often as the ammonia smell builds more quickly remaining right under their noses which leads to more respitory problems. Plus with them drinking more.... well you
Other ideas? Please share and I'll post them.