Any livestock could have infectious parasites or worms -- cattle, goats, sheep, deer, chickens, geese, ducks, turkeys, boars, etc.
Surely the vet can prescribe dewormer meds for the beasts.
One coworker I had said chickens have to be very thoroughly cleaned prior to cooking; "chicken is nasty," he said. Another man said he disliked chicken because of everything it eats but the other animals are specific about what they eat.
Some people rub their chickens with lemon juice or hot water to clean it off, they thoroughly pluck the feathers off or burn the feathers and hairs off the wings, and some rub salt on the wings not as a seasoning but as a cleaner. That's how fastidious some people get about food prep.
At the very least, after cleaning out the sink with Ajax/rinsing for sanitary reasons, one can run the chicken or chicken pieces under hot tap water and rub the chicken inside and out with the hot tap water to get whatever slimy stuff and residue is in/on the chicken before seasoning and cutting the skin and fat off. This applies to geese, ducks, Cornish game hens, pheasant or quail; also applies to lamb chops, pork chops, veal chops, beef ribs or pork ribs, steaks, fish, fillets, stew beef, prime rib or rump roast, pot roast, and also beef bones prior to roasting for 45 minutes to make sauces and stocks. After cleaning, defatting, skinning, deboning, cutting and plucking, cleaning out the sink with Ajax/rinsing for sanitary reasons is encouraged; washing one's hands goes without saying.
Kosher and halal butchers clean out the blood from the chickens and ducks and geese prior to selling them in the markets. Like kosher butchers, halal butchers slaughter the animal with a very sharp knife, drain the blood, then check the entrails for evidence of diseases, stamp the carcass and mark it with a label for lot numbering and dating.
Back in the day (1920s), the rabbi would put cross marks of the meat parts that were not kosher, put on the official seals marking the meat kosher. They washed down the carcasses, shrouded the beef by covering it with some sort of fabric, and cool it in huge refrigerators before delivery to market. The meat was cut to specifications for the store owners, who then delivered it to the retail kosher meat markets.
Kosher butchers, especially the Glatt kosher ones, put meats through a four-step process: Deveining, soaking. salting and final soaking.
They remove veins because it's forbidden to eat blood according to the Jewish dietary laws;
they soak the meat for half an hour submerged in water to get the rest of the blood out, and then they rinse them down to ensure there is no blood;
they apply kosher salt to completely cover the meat to draw the blood out, and it sits there for one hour;
the final soaking is rinsing very thoroughly with a power wash, dunked and rinsed twice, rinsing again, and then they sell it. Fresh Glatt kosher meat at your fingertips.
One woman who has cooking videos shows how to clean a fish by snipping off the fins, scraping off the scales, slitting and gutting the fish guts, and rubbing salt where the guts were removed to take the fishy smell out. Debone the fish by removing the spine and the top and bottom sides for the really tiny bones. check for eyes that are clear not cloudy, and fins that glitter, not slimy. Salmon, Chilean sea bass, and carp all have teeny tiny bones to even when cooked; when eating, extra care must be taken to pull apart the flesh so to not accidentally swallow a bone. And if they have a bad smell, avoid, because bacteria could be inside. Scaling and deboning and gutting fish is a very dirty job, which is why people pay the fishmonger extra dollar$ to do it.
And going back to the pigs, they have to have their pens cleaned out regularly to avoid infestation, just like chickens have to have their coops cleaned out, and the sheep/goats have their stalls cleaned out, to prevent infestation. Bacteria just LOVE to crash a pig/goat/sheep/chicken party, or any animal party for that matter.
