Reprinted with permission from the Rabbit News & Research Quarterly, V3N2, 1999

Gearing Up For Summer Heat

It's that time of year again; spring is fading away and the temperature has begun to rise. The mud dries out, the flies and mosquitos hatch, and all in all, we're headed for high summer. In some areas of the world, such as has been reported from the United Kingdom (Great Britain), the extremes of climate that exist in the US simply are not a concern. In other areas, heat is a given and must be dealt with year-round.

In this article, we'll assume a seasonal climate with a summer high of 110+ degrees F, a fairly common occurrence in many areas. Temperatures can spike to this extent for short periods, or remain above comfort level for rabbits for weeks on end. How can a rabbit breeder/owner efficiently deal with this sort of heat?

What Heat Can Do: We all know that excessive heat can kill or harm your rabbit, but how does this happen? When the rabbit is too hot, they must lose heat or suffer brain damage through cell death. The animal pants to assist in heat loss; as they pant, moisture is lost in great quantities. The lack of hydration results in low blood volume and thus less oxygen to the brain and other vital organs. When serious damage is done to these organs and brain, the rabbit will show neurological seizure signs and die.

Cooling of Rabbits: Rabbits must be cooled efficiently, as they do not sweat nor, save in extremity, do they pant. Their ears, with the large surface area and plentiful blood supply, are their radiating system for waste heat. Air movement, whether cooled or not; direct contact style cooling; and environmental control are three of the major ways in which rabbits may be kept alive in high temperature conditions.

Ventilation: Also known as air cooling, ventilation is most important in keeping the animals at a comfortable temperature. Moving air helps shift air heated by the ear's warmth away from the ear, replacing it with cooler air which can absorb the heat energy that the rabbit needs to lose. The cooler the moving air, the more efficiently the rabbit will lose heat. Methods of air cooling range from using fine misters to cool the surrounding air to fans which circulate the air in great volume, to swamp-cooler type apparatus which pulls air through a wet pad and out the opposite end of the rabbitry. Normal air conditioning units may well be used to cool the air which is then moved about by fans. Air circulation should be plentiful but not cyclonic; in other words, air movement is good but drafts and high winds are to be avoided.

Direct Cooling: The best method of direct cooling is by providing the animals clean, preferably cool, plentiful water. Some direct cooling of rabbits can be done with liquid water by wetting down the ears alone; combined with fans, this can be quite successful. Other methods of liquid water cooling are to spray the bellies only of the rabbits; lightly spray the entire area including the animals; provide crocks in which some rabbits like to dunk their ears; provide wet towels or burlap on which the animal may lie. Direct cooling can also take other forms; some rabbits adore being given frozen clay or slate tiles upon which they may sprawl; others enjoy frozen water bottles ranging in size from a few ounces to two liters; plain ice, thrown in a block in the cage, is also handy at shows and while traveling. Cold soda cans, frozen or just refrigerated, have been known to save lives.

Environmental Cooling: Cooling of an entire area can be quite a challenge. Shade, of course, is the premium and preferred method, as the respiration of the leaves will remove a large amount of ambient energy from the surroundings as well as provide the vital shade. Planting broadleaf, fast-growing trees is a simple and short chore which will pay you back many times over. Other plantings near or around the rabbitry area will also aid in heat removal. Air conditioning, although expensive for larger areas, can be the ticket in garages and other smaller rabbitries. Whether achieved by heat exchange or evaporative cooling, lowering the ambient temperatures will dramatically reduce heat loss in the barn. Remember that evaporative cooling requires a reasonable humidity level; there are levels at which water will not sufficiently evaporate to cool the air; in these cases, air conditioning is recommended.

Barn planning and insulation is a commonly neglected facet of cooling; a well planned rabbitry will save you much in the costs of cooling as well as retaining heat without moisture problems in the winter.

Hints and Tips:

Start now to accumulate bottles for ice. Save, rinse, fill and freeze all 20-oz or more bottles so that you have three for every cage. This allows for one out, one freezing, and one frozen ready for later in the day if needed.

Begin cooling before it gets hot. By running a swamp cooler or air conditioning unit earlier in the day, it is easier to keep the temperature at the desired level without having to play catch-up while your rabbits are suffering.

Freeze small bottles for use in reservoirs for automatic watering systems; this helps keep water cool for the rabbits to drink; also draining or allowing the last valves in the system to drip will keep cool water flowing.

Be prepared for power outages; have lots of extra ice on hand as well as a backup generator in the case of those persons who have too many to move them into a cooler place.

When traveling, toss a dampened thin towel or sheet over the rabbits, with plenty of air movement to ensure evaporative cooling; one may also place ice over the top. Shade in addition to this layer is always appreciated; keep one of the reflective silver tarps on hand to block windows where the sun shines in.

Keep the rabbitry clean and shoveled. Decomposition of manure creates heat, especially when damp. The less waste, the less heat. If you are raising worms, try moving them elsewhere and see if the temperature drops.

Always be ready to administer first aid to any rabbit showing distress; flat-out body positioning, panting, wet mouth and dewlap, twitching ears and dull eyes are signs that heat stress is occurring. Cool the rabbit gradually either by moving the rabbit into an air-conditioned area or by immersion of the ears or entire animal in tepid, not cold, water. Dry the rabbit completely after that and keep dry and at norma1 body temperature until recovery is complete. Offer plenty of fresh cool water in a dish or crock.