I am so sorry you lost your beautiful littlebunny. Without a necropsy, we can only guess, but many youngbunnies can succumb to Pasteurella after being subjected to stressfactors including being weaned young, diet change, pet storeenvironment, going to new home, handling and temperature changes.
Other pathogens can include Pseudomonas aeruginosa, Strep, Staph,Bordatella and other bacterial infections. Parasites can alsolower bunnies resistance to disease.
Most pet store bunnies are too young to be subjected to the abovestress factors, and many are in fact under legal sale age.Studies have indicated that the younger the bunny is when sold, thehigher the fatality rate is.
Shame on pet stores for insisiting on selling such young bunnies and shame on breeders for filling those orders :X
Pam