I’ve been looking at the petopedia page, and it’s really helpful!
Still have a few questions on feeding your pets though
How exactly does their hunger work? Do they only get hungry when active?
How many pets can you have “in your bag” at one time? Do they take up one slot like mounts?
Do they get hungry when they are inactive in your bag, or being stored with a stable master?
Thanks in advance!
All I know about hunters is the following:
Follow these rules, and you’ll do great!
As for hungry pets, no clue but my guess is throw meat or fruit at them every once in a while. Also, they do not take up a bag slow as they are a companion. You can house additional pets at the stable master (usually located outside inns). As far as I know, they only get angry with you when they die or you haven’t fed them in a while. Again, not in bag and stable master keeps them fed. GL!
Pet hunger/happiness status only changes when they are out & active with your Hunter. When they die they take a nice hit & need to be fed twice upon resurrection to get them well into the green (happy) state again. Don’t feed them a 2nd time until first time feeding buff runs its course. When feeding, wait for feeding buff to fall off pet before engaging in combat & such or it disrupts the feeding process & they lose some benefits of the feeding-over-time buff (it drops right off when combat starts).
The more loyalty your pet has the less often you have to feed it. (Keeping your pet happy in the early stages may get on your nerves.) In my experience if your pet is a meat eater, they prefer cooked food to raw.
Keep plenty of food on hand and make sure it’s the right level for your pet. Your pet does not lose happiness when it’s put away but will lose happiness whenever it’s out - active or not. Be sure to dismiss your pet if you plan on being afk for any length of time. 
Hunger is not a thing. Its loyalty. Loyalty is based on your friend level to the pet. The more time you spend with the pet, the better bond you get with them, the more time between unhappiness.
Mounts are kept in the stable. Visit a stable master. You can have 3 tamed pets at one time. 1 active and the others at the stable.
They do not lose loyalty when they are stabled. They do lose loyalty from being dismissed though so make sure they are topped off before switching.
Your pet’s hunter will slowly deplete over time. Activity level seems to have a slight effect on how quickly it depletes (fighting vs standing around). Anytime your pet is not with you you can think of it as putting them into stasis, this includes the stable.
If you’re 60 and feeding your pet lvl 45 food it will only take 1 piece to get them from yellow to green.
LOL…all mistakes I made when I first started playing. 
Pets only need to eat when you have them active. When a pet dies it will need to eat, at lower obedience levels it will need to eat more often. You can have up to three pets, one active, and two stabled. Pets don’t take up bag space.
Awesome; very helpful! Thanks guys!
Well, there’s a bit to it really. It depends on what level the pet is first. If the pet is below level 15, it could abandon you if you don’t use it enough. I think 10 minutes of inactivity or more means there’s a chance it could abandon you even if it is happy and well fed. I am unclear on the specifics but I do know lower level pets can abandon you based on inactivity. Pets above level 25 or so only need to be fed regularly and happy, but they will not abandon owners for inactivity. This did exist in the original game but these are one of those finer details that are a little wonky on Classic.
Something that worked for me was dismissing pet when inactive at lower levels.
It’s pretty simple, if the little pet window below pet portrait turns yellow it needs to be fed.
The amount of damage a pet produces is reduced based on unhappiness. A yellow window means your pet is only doing 75% of dps capacity I believe, and it gets worse if it turns red.
Pets do not take up a slot in anywhere but the stable. You can only have up to two pets in stable, with one active. You dismiss on pet portrait, and use whistle (which you can opt to put on your bar somewhere) to call back back from being dismissed.
Additional suggestions can be found on various websites. Some have pet abilities like “attack” and forced “passive” bound to their mouse wheel while others make a macro tying hunters mark and pet attack to the same action. Some have “growl” always inactive and bound to a key on their keyboard. As you can tell, this could get lengthy, so I suggest websites.
I hope I have helped.
I will not tell you how it is supposed to work, but I will tell you how its actually functioning right now.
They lose happiness after a certain amount of time killing mobs requiring you to feed him to raise his happiness back up. They also lose happiness from dying and can also lose happiness from being dismissed. Their happiness is also being affecting from taking Flight paths as well. I think this may be because they’re being automatically dismissed.
When you tame a pet it just becomes your ally. There is no icon or item like a mount. You get 3 stable slots meaning 3 pets. You can only have 1 pet with you at a time.
They don’t lose happiness levels while being stored in the stable master.
TWO EDITS BELOW
I’ve run a hunter since vanilla days, more than one actually lol, they are my favorite class.
There is a lot of good info here, so i’m going to condense it all into this post, and add a few things I think are worthy of being mentioned.
3 pets max, 1 out, 2 in stables… 1st stable slot is 1 gold, the second one is 5 gold. They do not take up bag space, lol, which is good, hunters already have bag space issues with ammo, but that is perfectly fine with me, I love having my ammo and feed pet back.
Hunger: Feed as soon as they go yellow, if not right before they go yellow, you will really notice a big difference when they are fighting as yellow, or it changes in mid fight. You will eventually get a good feeling on how often you need to feed, based on activity, loyalty level (more often when loyalty is low) and level of food you feed it. Just feed it regular healing foods, buff foods do not apply to the pet, no sense wasting those!
Red is bad. When the pet goes red, it can and will run away if you don’t feed it. How long that takes I’m not sure, never let one run away to be honest. The last thing you want for it to do is run away in the middle of something, and they will. My daughter used to have serious issues with feeding her pets in vanilla and had several run away. Got her killed a time or two as well, you’d of thought she’d learn.
Pets do NOT level while stabled! You tame one, get it up in levels to be your level, and loyalty is up to 6, then stable it, it will remain at that stage, unlike in retail where it comes out and immediate goes up to whatever level you are. If I have two pets I want to keep usable, I swap every other level just to get the second one up to speed, far easier to keep up with it than to try to catch up to it.
Watch your combat log when you feed the pet. It will show you fed it and what you fed it, and then it will start with name of pet gained 35 Happiness from food Depending on how hungry he is, will determine how many times you see that. IF the last one you see also shows 35 then feed it again. Once it is completely fed, it will start to lower on numbers, until it finishes with zero.
Once you pull a pet out of the stable, feed it. While they don’t ‘lose’ nearly as much, those stable masters have issues with feeding. You can put a fully fed pet in showing they gain zero happiness, and when you pull it out, it will still be green, but have multiple lines of 35 happiness gained.
Keep food levels as close to pet levels as possible. Yes, your level 35 pet will eat level 15 food, but it’s going to take more of it to get fully fed. Not sure if it will still eat level 5 food though, if it goes too low, your pet will refuse it.
Cooked food is better than raw, but they will eat raw if that is all you have, hence, cooking on hunters is about as important as fishing. Bears and cats I know, will eat meat and fish, where some only eat meat, or fruit (the worst, not that many fruit sellers out there).
Hint: Mail an alt a full mail worth of ammo, and another mail with multiple stacks of a good on level food (seriously, don’t buy it from vendors, go out and kill stuff or fish, or it gets way too expensive!), then you are only one mailbox away from getting your needed supplies. This is especially important if you have a pet with a picky diet, you just can’t find fruit, fungus, bread, just anywhere. And there is nothing worse than running out of ammo. Nothing. Mail it to a banker alt, log them in and hit return mail. The return is free, and instant. The cost of the original mail is well worth it, compared to having to buy ammo or pet food at the nearest vendor.
Don’t follow the ‘advice’ by your first response, Perol, lol, that is all false. DO follow the advice of the next one, Kissaki, that info is correct. I still see a lot of hunters tossing 4-5 pieces of food at their pet in a rush, that’s just wasting food.
Pets actually get hungry faster if they are inactive, like when you are doing your banking, AH, mailing, etc. If you aren’t going to be fighting for a while, dismiss him. They tend to not be as hungry when constantly fighting, but keep an eye on them and catch it as soon as it turns yellow. The lower level the
food, the faster they get hungry regardless…can’t stress this enough.
Make sure you do not take your regular pet with you when you go to tame another! Put him in the stable, and if you are going into a dense with mob area, take someone with you to help. BM hunters without pets are kind of like mages without wands. You can still get the job done but its gonna cost you. Tame a ‘throwaway’ pet as soon as you can get one close to your level, especially if you think you will be waiting for a respawn.
Do not tame 3 pets you like, too early. You need to have a stable slot open for when you need to learn a new skill. Until you have learned all the skills available, keep a slot open, and then, you will be covered regardless of which type pet you have. I will be taming all kinds in classic as well as learning all the ranks to each skill, same as I did in vanilla, even if I never plan to use that type pet in the end, just so when I do tame my final pets, (dps, tank and pvp pets), I have everything I need and will never have to abandon one …because…
I have never seen this happen. A green pet running away that is. Not saying it doesn’t, just saying i’ve never seen it. I might have to go find a lowbie pet just to test this one 
I don’t tend to tame pets that far below my level either however, since it takes so darn long for them to level up, and the hunter has to be getting xp or honor in order for the pet to gain anything, so the pet is pretty much useless if the level is too low. That’s another reason to keep up levels if you have permanent pets in the stables. Useless and slow to level them.
That’s all I can think of for now, if I come up with something else I’ll edit to add.
EDITED TO ADD:
This is awesome info on flying pets:
Thanks Rotsta.
EDITED TO ADD:
Pet testing on runaway green lower level pets as per end of this thread, check the thread I posted two posts down from here for an update, I did check it out.
Very important point. I was wondering if any one was going to point that out.
Just letting ya know, curiosity got the best of me, I’m currently in game now, testing this lol.
EDITED FOR RESULTS:
Ok this has been one long hour plus lol, but here is what I have so far.
5:01 AM - Level 41 hunter, tamed the first level 7 wolf I found outside of IF.
Fed level 5 haunch of meat off vendor as soon as tame finished.
5:05 AM - stopped moving after going back to IF
5:17 AM - he turned yellow. Fed again
From here out I did nothing.
5:35 AM he turned yellow again.
5:49 AM he turned red
6:04 AM I got booted lol, immediately logged back in.
6:19 AM he finally poofed.
Feed happiness:
Tame feed:
Feed 1 - 9 times 35 happiness
Feed 2 - 9 times 35 happiness
Feed 3 - 7 times 35 happiness, then 20.5 and 1.9
Feed 4 - 3.8, 2.0, 2.1, 1.8, 2.1 happiness, so this feed not necessary.
First yellow Feed:
Feed 1 - 9 times 35 happiness
Feed 2 - 24.1, 1.9, 2.2, 1.9, 1.9 happiness.
Now here is another interesting thing. My lvl 40 6 loyalty cat that I put in the stables to test this? Fed him right before, and pulled him out right after.
I tried giving him that lvl 5 food, he did eat it, but…his happiness from it was only 8.8 x 3 times, (considerably less than 35), 1 x 0.9 and 3 x 0.7, so while the food he did eat, (won’t at 45 at latest), the amount of happiness he gained was minor. He did however lose that much in just over an hour time in the stable, so they do lose happiness while in stables. How low they will go I do not know, I have a turtle in there also from about a week or so ago? He’s still green, so hopefully they don’t drop below green. If they do, I’m firing that stable person lol.
All in all, that was a interesting experiment. I knew there was not a reason I did not feel sorry for my daughter when she kept losing pets. They give more than ample time to feed them before they poof.
It also seems to debunk the pet running away even when green due to lower levels idea. Can’t get much lower than I got after all.
On that note, time for bed.
This is really excellent. I’ll add just a couple of things you may agree with. I usually heal in groups and don’t have a lot of time to do a lot of groups with my melee alts but tank and melee friends have told me they hate flying pets, especially bats, in groups because the large wings get in the way when they’re trying to target. Some hunters will get a wind serpent for groups and turn off everything except lightning breach and keep it by their side to keep it out of aoe. I think that’s over kill, pets don’t die easily in melee situations. Some will get a wolf for the furious howl that buffs anyone close to it. Some anal retentive guilds that think you have to maximize every single point of dps will insist on a wolf. It’s nice if you’re soloing dungeons to have a pet with screech since it’s an aoe and helps the pet hold aggro on a group of mobs. Thunder stomp is great for that too but it’s on a cool down. A minute I think?
Oh good advice on flying pets, I hate those in small areas. But they are awesome in pvp
I also on the few dungeons I ran in vanilla, found that any aoe spell on a pet is pretty much a no go unless you are manually setting it off.
Even in the open world that can get you into a world of hurt fast lol, in condense areas.
I’ll add when I add in my findings on runaway pets. So far I fed it once, and it’s been 31 minutes since I tamed it, have not moved one iota other than feeding it that one time for 15 minutes. gonna let it go yellow this time and not feed.
There was a certain point in the expansion changes when there was a pet, strider? with an in combat res. That was often a fun pet to bring to groups.