I'm bumping this because (1) it's awesome and totally needed and (2) there's one glaring omission (or maybe not - a search didn't turn it up, but I've been lead wrong by that before).
Historically accurate reconstructions of surgery in the 18th and 19th century usually include a sink right by the operating table to show the surgeon walking into the theatre without any kind of scrubbing - often introducing dirt, grit, grease, and even (if he had just come from a minor surgery) other patients' bodily fluids - and then, after he was finished, washing his hands.
The period between the invention of ether and chloroform and the discrediting of spontaneous generation (and, hilariously, the miasma theory of disease) is in the history of medicine often referred to as the Dark Age of Surgery. Because surgical prep no longer involved either knocking someone out with something lightweight like liquor or cautious concussion or strangulation or giving them something to bite down on, surgery stopped being desperate and careful and became something almost commonplace. Where before surgery might have waited until horrible pain or immediate threat to life or limb (gangrene, enormous benign tumors / inevitably fatal cancers, etc), a new confidence came into the field, and limb operations became routine and painless. Worse was the change in boldness of surgeons - outside of the extremities (which could in any emergency be amputated, cauterized, and prosthetized - something known as far back as ancient Egypt), classical surgery had to do mainly with ducts, protruberances, and exposed holes - so dentistry and the cutting of kidney stones (in many medical cultures distinct from both surgery and medicine per-se, a distinction preserved by abjuration of cutting out stones in the Hippocratic Oath and the extreme specialization of European dentistry), along with less savory practices having to do with the genitals (on which more later - not as nasty as it sounds, I promise). In short, surgeons considered fiddling with anything they could not hack off with a saw and sear shut irresponsible.
During the Dark Age, that belief basically disappeared; while extreme caution was taken to avoid physically damaging the organs of the torso, sufficient understanding had been developed from centuries of previously almost useless study of cadavers' body cavities to allow for effective surgical intervention in various torso-based problems, including hernias and cancers. This is where we get to why it was a Dark Age: without the understanding necessary to avoid infection, surgeries were routinely performed in which iatrogenic morbidity approached 100%. By the time the first glimmering of understanding of sterilization had arose (a quarter century later!) a general prejudice against internal operations had developed; when Lister brought the work he, Semmelweis, and Oliver Wendell Holmes Sr. had done in non-miasmic contamination to general understanding, it still took some time to understand that the body cavities were prone to infection well beyond the capacities of contemporary sterilization to handle.
This problem was common to all surgery in the body cavities, including the removal of bladder stones (worth looking up, but painful even to think about) Samuel Pepys carried the egg-sized stone he and a surgeon had cut (conscious!) out of his bladder - through his perineum - with him often as a memento and a stark testiment to how awful a problem stone removal could resolve, but evidence suggests that his entire urinary tract was infested with gangrene and it might have contributed to his death. As the diary showed he remained a capable and vigorous sort, but on the other hand he wasn't a friggin' stone miner. On the other hand, in feasibility terms duct-work would be the single most likely form of surgery for dwarves to practice. In societies without the strong taboos against molesting any dead (rather the more common taboos against disfiguring corpses you know personally), anatomical knowledge would be sufficient to allow for surgical intervention within the realm of the ducts - so some ear/nose/throat surgery, the removal of certain parasites, the cutting of bladder stones, the treatment of stomach and respiratory ailments, and the more medical/surgical form of midwifery that existed before the Industrial-era separation of obstetrics and 'traditional' birth.
Especially if dwarves have access to reasonably sophisticated anaesthetics, they would probably suffer the same problem, requiring the introduction of infection somehow. A prosthesis status would also be helpful; it would slightly reduce speed, weapon accuracy and power, and performance in certain skills, but it'd be far preferable to the losses inflicted by the absence of a limb. Prosthetics, crutches, litters, primitive wheelchairs, and other such devices would take sophistication to build well - in some cases, requiring as many as four or five skills to build - but would confer various advantages:
- Wounds would heal at the same rate of a bed-ridden dwarf, but the dwarf could gather food and alcohol for itself in one of several ways, and even under certain circumstances working and fighting.
- A dwarf with permanent and crippling injuries could use them to remain mobile and useful. This includes military, especially for pike/spear and crossbow wielders, but mobility problems would be present and in any case they'd pose a disadvantage in wrestling.
- The entire prosthesis family would fall into certain categories: replacement limbs (splints and immobilizers for damaged limbs and pegs and hooks for mangled/amputated ones), hauling-enablers (litters), self-haulers (crutches), and ambihaulers (wheelchairs). The first category simply replace limbs; the latter categories obviate the need for their use, allowing dwarves to either (a) be hauled by a dwarf with healthcare enabled, if possible while wielding or hauling items themselves; or (b) to 'haul themselves', removing the ability to move in combat or during the use of item-centered skills but allowing for basic mobility.
For self-hauling, there would be a huge incentive to keep the ground soft and the z-levels ramp-spanned. Dwarves hauling themselves on crutches or wheelchairs would receive minor unhappy thoughts from 'walking' over rough or muddy ground and either would not be able to traverse stairs or would have fairly heavy negative thoughts from them.
Hauled dwarves would function basically as normal, but would be able to function from haul - so legendary miners with a broken leg could still mine somewhat slower instead of being trapped in bed, and so on. There would be a fairly heavy negative thought from being dropped off short of the destination the way normal hauled items are.
- If possible, dwarves with two or more limbs intact would still be able to swim, slightly slower, and maybe wrestle almost as normal in water.
- And old, sick, or disabled nobles would obviously expect not just a litter, but their own litter and a fairly nice one at that.
- The litter, wheelchair, and any other device making the dwarf other-haulable would count as a bed for sleeping purposes. (Indeed, some early litters were basically a bed on sticks.)
In general, the aim here is to avoid the fairly ahistorical position the injury simulator's limits occasionally impose in which someone with certain perfectly viable injuries is basically the (non-)walking dead. A king of Denmark ruled and fought from inside a shield due to a congenital condition which essentially turned his bones to pudding, for God's sake - the dwarves can do better than that.
There should be a Healthcare profession, including a noble (the physician), skills (dentistry, surgery, ductwork), and a few specialized buildings: an anatomist's allowing the development of surgical skills with corpses at the expense of unhappy thoughts by nearby dwarves and particularly traditional or empathetic friends or relatives; an apothecary's office for the noble, whose presence reduces the effects of miasma and who dwarves will occasionally receive happy thoughts from visiting and which sells extracts during the economy; the (duct) clinic, which acts as a non-noble version of the physician for older dwarves and recent mothers, and the hospital and surgery, which store prostheses and medical salves, immediately heal some minor injuries, have a chance of un-mangling/breaking certain organs and a better chance of un-mangling/breaking limbs, and which fit and assign prostheses and haulers, VERY loud, constant miasma (and dwarf chunks!), and non-functional if in direct light.
The ductworker profession would also handle desexing animals, which would have [DESEX-M] and [DESEX-F] tags, possibly with numbers and body parts dictating the possibility injured organs (neutering a dog wouldn't be too much of a worry, but neutering a crow involved poking around close to the intestines and liver). A special name might be added for some desexed animals, and the main effect would be preventing them from either emitting or receiving procreative spores. If possible, other sex symbols would be used to distinguish them easily - small-* for males and big-* for females. (Similar use of symbols might be fitting for species like antmen which (should) breed without males, but adding non-tetrapoda sexes might be more trouble than it's worth.)
From our perspective (largely focused on large mammals), it would seem to make sense that desexing would be male-limited, but especially for cloacal animals or insects, it would be well within the range of possibility in the tech setting to reduce the breeding population for whatever reason by reducing the number of breeding females. If your fortress is routinely breeding giant cave spiders and you actually have a way of convincing them to part with their gonads peaceably, neither sex would be appreciably more difficult to do so with. Most mammals would be male-exclusive, though.
On the other hand, duct clinics with a focus on obstetetrics/midwifery should do various things to simulate the overall improvement of family health from that: increase the chance of multiple birth and the likeliness of pregnancy (sorted by animals - one might want horses to give birth more often but not cats or dwarves, or vice-versa), reduce the baby and child age cut-offs, and otherwise generally allow them to turn Dwarven reproduction from an oddity into a strong complement and possibly even alternative to heavy immigration.
The other possible addition, although I don't know how well it would balance out, would be the possibility of adding the very strong psychosomatic effects of medically ineffective remedies common before the systematization of anatomy, infection, and injury. While for life-threatening or debilitating injury the knowledge to effectively cure or treat the condition has a long history, just because bloodletting, humor-balancing, and various panacea did not medically do what they sought to - and were even sometimes a danger to health - doesn't mean they were useless as social devices. In a society which believes in bloodletting, even though that kind of 'treatment' for disease would cause anemia and minor limb injury, the psychological effect of access to and use of the "treatment" is difficult to overstate. This would provide a big opportunity in the psychology-dominated social system of DF - in addition to utilitarian and rehabilitatory measures, medical facilities and professions might exist which inflicted minor, recoverable, and non-rest-requiring injury on unhappy or insane dwarves in exchange for happy thoughts or alleviation of their distress. We're used to modern medicine and might not want a thing to do with bloodletting as a "cure" for anything, but we'd think fairly different if we were raised to believe diseases and misery were often caused by an excess of blood.
Besides all that, the one most important thing is this: infection is a HUGE part of medicine and surgery. If dwarves have anaesthetics worth the name, they're definitely going to have to deal with it, and its omission is heavily at contrast with the medical realities of the period. Remember, up until WW1 most casualties of war died of disease - that even includes the ugly, awful bloodbaths like specific Napoleonic theatres and the Thirty Years' War. In the prescientific era, someone who suffered an even mild puncture of the gut while defending a swamp in the summer had a lot more to worry about than vomiting.