A) The most likely cause of these large swellings is a cyst containing tapeworm larvae. The most common organism which produces cysts of this sort is Cysticercus pisiformis, the larval stage of the tapeworm Taenia pisiformis`, a parasite which inhabits the small intestine of carnivores. The rabbit is an intermediate host, which ingests the tapeworm?s eggs from the grass on which it feeds. After hatching, the tapeworm larvae eventually migrate to the rabbit?s liver and are ingested by any predator that kills and eats the rabbit.
An alternative possible cause of the swelling, according to a GWCT pathologist, is post-traumatic oedema caused by fighting. I would recommend that any carcases displaying similar signs be destroyed, preferably by means of incineration. You should certainly not allow them to be eaten by dogs.