random stuff i learned today: dog digestion

as a biology nerd i have a duty to study up on most chordates - doubly so thanks to my lab-tech class (lots of dissections, higher level bio stuff, etc). here's what i learned just now:

-dogs have a similar digestive tract and makeup to that of humans, but quantities of which and what organs do the most work are different. has mostly same makeup as us - a mouth, a pharynx which food goes down, a stomach with acid which stores & breaks down food, then intestines and the colon which perform further digestion. path is much the same as in humans: mouth > pharynx > stomach > intestine > colon > excrement. 

-key difference between dogs and humans is in the details: in humans, chemical digestion begins in our mouth via saliva (specifically, the enzymes in our saliva). in a dog - no such enzymes exist in their saliva - their spit only acts as a mechanical lubricant for food to move around easier. this is where that myth of a dog's mouth being cleaner than a human's mouth comes from - neither are necessarily cleaner than one another. each still transmits disease just the same. 
after that - our stomachs are much less acidic than a dog's (specifically, their stomach acid is 100 times more acidic than a human's), and a dog's entire digestive system only takes ~8 hours, whereas human digestion takes at least 24-72 hours. dogs are much quicker digesting - and their stomach acidity allows them to eat things humans usually wouldn't be able to without getting sick. rather than humans where a majority of digestion happens in the intestines - dogs' take place mostly in the stomach, speeding up the process, although sacrificing some nutrition along the way, and allowing them to avoid pathogens in the process. their intestines are much shorter than a human's as well - further cementing their fast digestion over quality, slow digestion. 

in short: all that minutae is what allows dogs to eat their own poop and all other manner of nasty things without being sick - their physiology allows quicker, although less efficient digestion of a broader range of things. i'd be a nerd and get into their auditorial abilities too (frequencies of audio, human eardrum vs dog's) - but i'm short on time for today.