I'm growing increasingly resentful of having pets.
Try a healer, and you'll be glad you have your pet(s) with you!
If you don't have a leash or a magic whistle, then you have no way of controlling them and getting them to stay close to you except with a tripe ration, and even then they slow you down. Even if you have a leash, they're faster but you're always dragging them, causing them to squeal and whine, waking up monsters you'd have preferred stayed asleep. Slowing down for them wastes even MORE time.
Even a tin whistle will work to draw your pets close. Don't venture too far off away from your pets, for without visual contact they are less likely to move in your direction. When walking into a corridor, let your pet go in first, and use yourself to block the way back, so they must go in the direction you want.
Leash has a max. length of 2 - so if there're two spaces between you and your leashed pet, wait. At that point it can either stay still or move close to you, because it won't yank on it's own neck, so it will move closer to you.
Keep a wand of speed monster handy to zap your pets.
Plus, Getting corpses and tins of specific monsters becomes a REAL challenge when you have a pet, as they're opportunistic little assholes that'll leap at the opportunity to eat things you might have wanted to tin, which makes getting tins of valuable creatures (like giants, nurses, or chameleons) to be a pain in the ass.
Make use of boulders, cursed items, corridors and doors. Most pets can't open doors; and locked doors will keep all of them away (you don't keep pudding as pets, do you?). Pets are very unwilling to step onto cursed items (with no food in that same square), so you can abuse that fact.
Displace your pet and deal the killing blow yourself, and you will have the corpse.
They take forever eating too, finish the damn thing!
Though monsters ignore them when they're eating... that makes eating pets a very good shield.
Then they interfere with Elbereths, because they don't respect it, they'll just walk all over it and degrade it, and possibly pick up the gold coin or something that you dropped on it to keep it active.
Drop a cursed item on the square; use container if possible.
Also, you can't use conflict, because then they'll attack you, and standing on an Elbereth doesn't help, cause they don't respect it!
If you use conflict you have no friends (nor do you need any)... so either stick your tripe ration into a bag and stay away, or leave your pets on the previous level and conflict-kill first before getting the pets down there with you.
In the case of ponies, you have to REALLY go out of your way to keep your pet alive, you have to chat to it to discern how it's hunger is doing, and you have to feed it fruits and vegetables only, both of which can EASILY get to be in short supply.
Horses will eat rations when very hungry (though max HP will be reduced at that stage), and they are indeed hard to feed. You should keep all vegetables and lichen for them. And a war horse is pretty tough.
EVEN THEN, if in the heat of battle you accidentally hit your pet with a wand of lightning (cause it just won't GET OUT OF THE FUCKING WAY!) and you kill it, then you lose like 15 alignment and 1 luck.
I don't use lightning wands to kill... blinding is bad even if you have unihorn. You never know what detail you've missed... like the message of a soldier picking up the cockatrice corpse you just created with the wand. I reserve my lightning wands for emergency E-word only.
and even then, you can't even eat or sacrifice the damn things without being severely punished.
Call all your pets. Then unless a mind flayer got to you, you won't eat them in mistake.
So I've just taken to abandoning the little bastards the moment I can afford it, it's always for the best.
Pets are indispensable to me early on; the BU/C check, combat support and doing Sokoban early (you can't easily handle the monsters there all by yourself). Plus the chance of getting it polymorphed into a dragon and then leaving me its scales... with an enchant armor scroll that's -9 AC. I'll take any colour of dragon.
I've read about a nice pet trick, and I am going to try it in my game. Keep a cursed scroll of genocide and a blessed scroll of taming. On Astral plane, wait for your free turn (from fast or very fast). Reverse genocide purple worms and tame them. Repeat as many times as you like or as your resources last. Use a wand of teleport and send them forth, and enjoy the *Burrrrp!* everywhere as they swallow things whole.