In general, purebreds lack hybridvitality. There are certain breeds that are more inbred thanothers and any of those would be shorter lived, more prone to illnessand more prone to reproductive problems. The smaller the genepool, the more tendency towards genetic weakness.
The Dwarf Hotot is one breed that is especially prone to health problems due to poor nerve development in the gut.
The exact cause of sudden or "shock" deaths has not been determined asthis also happens in the wild during natural populationcycles. Domestic rabbits are more prone to sudden death after2 years of close line breeding.
Pam