In the last ten years or so of butchering wild hogs, the MAJOR danger signs that I've noted have mostly been the result of boars fighting.
As such, they often will have penetrating subcutaneous wounds into their musculature beneath their shields where another boars tusks have entered, also sometimes their scrotal sac is punctured since it is so large and exposed and very thin epidermis covering it to protect the crown jewels.
Three times I have found a large softball sized abscess under the shield up against the scapula filled with pus, I have also seen this twice in their scrotum.
Most likely, this is a gram positive Staphylococcus aureus infection (think flesh eating bacteria), although hogs often get Erysipelothrix rhusiopathiae, another gram positive bacteria that causes septicemia and is zoonotic to humans.
The danger with Staph infections, besides the fact that the bacteria is highly concentrated and hyper infectious to you itself, is that Staph excretes a powerful endotoxin that is super bad to ingest and will make you sick as a dog (think bad food poisoning). So do not eat any carcasses with any pus sacs.....it does not help to cut out the infected pus sac as the endotoxin is water soluable and already has permeated the entire animal....
I have also found a couple of the large boars/sows I have taken down with previous older .223 and .308 slugs in their shoulders with the resulting scar tissue and bone/muscular tissue damage from previous shootings that they recovered from in the past, generally this is not a problem health wise if you just cut around this damaged tissue, it is not infectious.
In general terms, wild animals do not live long healthy productive lives in the wild when ill or sickly, they die. So 99.8% of the time they are basically GTG if they are mobile, eating, and running around, a sickly animal is immediate prey or dies of disease/stress/starvation in the wild.
But, you do need to be aware, especially with Brucellosis and Leptosporosis bacteria which are zoonotic for humans and cause devastating diseases in man. If you ever are sick as a dog and at the docs for some bizarre reason, be sure to let the doc know that you are a hog hunter as most general practitioners/internists do NOT have a clue to diagnose these types of zoonotic diseases without a referral to an infectious disease specialist.
And for God's sake, if you ever get a tick on you, carefully remove it and put it in an aspirin bottle with Isoproponal rubbing alcohol so if you ever do come down with any of the large number of terrible tick transmitted diseases, they can extract the DNA from your preserved tick and find out what the [beeep] you got from the tick. Ticks are bad, real bad......ticks really sux bad.