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.
Corncob litter is not recommended as bedding for hedgehogs, for a number of reasons. The danger of it getting caught in delicate places still exists, though not as likely as, say, clumping cat litters. There have also been many cases of mites that pointed back to the use of corncob bedding as the source.