By rhd, I assume you mean VHD - they are more likely to be found dead
1967spud is right RHD Rabbit Haemorrhagic Disease otherwise known as Calicivirus.
Jimbo
Just to clear this up as I got a little confused... VHD and RHD are the same thing Viral/Rabbit Haemorrhagic Disease... According to google can also be called RCD Rabbit Calicivirus Disease as Jimbo said...
Is it not a bit late/cold in the year for mixy?