Heart block: Failure of the heart's normal rhythm controls leading to arrhythmia. Heart block: Impairment of conduction in heart excitation. It is often applied specifically to atrioventricular heart block. Heart block: recurrent sudden attacks of unconsciousness caused by impaired conduction of the impulse that regulates the heartbeat.
For pet rabbits and show rabbits, pine is completely safe for rabbit litter, especially kiln-dried pine. Kiln-dried pine is also the cheapest rabbit litter on the market. And since it does a comparable job to all the other litters, pine shavings as rabbit litter and rabbit bedding gets our top vote. See Rabbit Bedding for comparisons with several other rabbit bedding materials, and more recommendations.
Make sure that the hutch is large enough for your rabbit to stretch full out, and high enough for your rabbit to stand upright. Dutch rabbits are generally comfortable in a 4' x 2' hutch. If kept outdoors, the hutch should have a dark enclosed area to provide your rabbit with a quiet space.