There may be those who disagree, but I have found that most responsible breeders do not breed their rabbits in the summer, particularly in the southern states. While it is true that some rabbit breeds are more heat hardy than others and those in the most northern areas of the United States have cooler summers, the Silver Fox is a breed that was developed to have unique, long, stand-up fur coat and it is best for the cooler climates or at least colder seasons. It is also a heavier, meaty rabbit therefore one that is not built for the heat that way either.
In the wild, rabbits sleep in holes dug out in the ground where the temperatures are consistently in the 50's. Some rabbit breeders do the colony style method advocating it is a more natural way to raise rabbits and requires less work for the rabbit keeper. This method allows rabbits to create burrows like their wild cousins. However, the downside of the colony method outweighs the upside of it for those who have chosen cages. The list includes parasites, difficult to isolate diseases, susceptible to predators, escapes, fighting among themselves (sometimes to the death), kits drowning in the nest when it rains...and so on.
Rabbits die easier than we would like from many things, but heat distress or heat stroke affects even the healthiest one. The main cooling system built into rabbits is their ears; this is why hares in the dessert have huge ears (besides that they better alert them to predators). When rabbits are overwhelmed with heat so that their ears are not cooling them enough, they will pant which causes wetness on their chins. That is the first and may be the only sign one will see that the rabbit is in distress from the heat.
Breeders do different things to keep their caged rabbits cool in the summer. The main components to keeping rabbits cool is ambient shade and good air flow. My rabbits are in a shaded area on the edge of a woods and we provide fans for them once the temperatures begin peaking at around 85°F.
In regards to fans, they need to be kept clean of fur that will accumulate on them, as many barn fires have been caused by fans bound up with hair and dust in the motors. One of the advantages of using fans is less bugs, like flies, mosquitoes, no-see-ums, and the like. Another advantage is it keeps odors down as well. Then, there is this: rabbits love the air flow when it is hot.
Rabbits in or next to metal buildings can be a concern even if the rabbits are well shaded. Metal in sunlight heats up and conducts the heat, so cages along metal buildings can become too hot for the rabbits even with good air flow. If such a setup is necessary, the north side is going to be the coolest with the least sunlight on the metal, however the north may also be the most exposed to extreme winter conditions as well.
There are additional methods to helping the buns chill in the heat, like providing frozen water bottles to lie against or ceramic tiles to lie on. Some are even using homemade swamp coolers with blocks of ice melting in a cooler outfitted with a fan and a directional vent.
Some breeders want heat-hardy rabbits so they provide nothing extra, but a rabbit surviving one summer may not survive the next. They may have shorter life spans, which may be fine for the meat breeder, but not the breeder trying to preserve the best of the breed. As a Silver Fox keeper with that goal and accounting for their long fur, I feel I should do some measures to preserve my rabbits lives in the summer heat.
With that said, breeding in the summer is not even an option for me. I have not lost any rabbits to heat stroke yet, but I am ever mindful how easy it is to do so and this is why I do not breed rabbits at all in the summer. Most breeders will warn how the bucks become heat-sterile and that is the only reason they end up not having kindles in the summer. I personally take this as a sign from nature that the does should not be pregnant in the heat of summer as well. Pregnancy makes a doe hotter to begin with at any time of the year, so why take a chance on losing her to the summer heat?
I have read breeders bragging on how they breed in the summer and I have read many breeders complaining about losing good brood does during pregnancy and during labor as well as kits in the nest in the summer. Often they do not associate it to the heat. In all honesty, these things can and do happen through out the year, but the added risk of heat is not worth it to me.