When people try to domesticate feral cat and dogs and take them for a vet check up it seems that they are often full of various parasitic worms and have to be de-wormed. Is this natural for all wild animals? Are most wild animals chock full of worms?
Absolutely - and most humans on the planet are too (first hit searching for “human parasitic worm load” - not for the queasy). For a full treatise, see Carl Zimmer’s Parasite Rex.