Due to that I used to cheat through lifestages and a sim's motive, I've never really added pets (but I have added mods and learned about those cheat guides so I know how to keep the pets in sync when needed) to any custom hood. Dealing with lots of households even with max motives kept me busy enough. A while ago, I downsized my custom hood and merged orphans, single parents (fathers with their uncle or sibling, single mothers started to open a monastry) but still have about 15 tiny families (single parents w. 1-2 kids or a couple with 1 kid) and was planning to add pets to some of them. I'm familiare with the vanilla guidelines about pets (but I've a couple of questions regarding gameplays:

I like to keep their race somewhat clean so I only allow same race breed eachother. I.e. my first family had two "husky" dogs, these had four puppies, where three will moving to other families. For these three husky's, I'll create new CAS-pets to breed with these. I probably won't let all of them breed, because that way they would occupy way too many families and I don't like to play very large families. With sims Im more strict with this, but I won't be with pets. But how does family tree works for pets - how far do you need to go before being able to breed blood related pets?

Since pets also add characterfiles and usually give more "kids" than sims, I feel like they would add alot of them over time. As I don't like adding townies and prefer to play and manage all of my sims, I like to do this with pets as well, so when a puppy/kitty reach adult, I move in a "sim holder" (non playable cas) who will take away the extra puppies/kittens to other families. So the question is: How you deal with population control when it comes to pets?

Third, how do you like to decide how many pets to add? (a more personal question for the other simmer player. )
Like Ive about 15 families who are "suitable" (read: have place for them), but I feel like having 15 set of them would increase the pet population very quickly and I fear like I would overdo it like I did when giving kids to the founders. So far Ive only added the husky's. they already occupy four of them and added extra husky's for mates for the litter. So now, Ive 10 husky's dogs in the hood.

The last question. How much pet beds, those pet houses and bowls do you general need? Like, can puppies/kittens share the beds? (really a noob in this area ).

Pets can and can not share beds. By that I mean that they can't sleep in the same bed at once, but pets don't mind sleeping in a bed another pet has slept in. How many to add depends on if you will allow your pets to sleep on Sim furniture or not. In some households I won't have pet beds, as I feel the family would let them sleep in their beds. If they are not at all allowed on Sim furniture, then I will have one pet bed for each pet at least. If it's a big house and there is room, I'll probably have some spread out in different parts of the house.

The number of bowls depends on how often you want to refill them (and how finicky your pets are, some refuse to share bowls). I usually go with at least two, so that if one runs out they have a second to go to. If there is more than two pets, I'll add another bowl (or more, depending on the number of pets). I know I tend to forget to look, so I like to have some room to forget without the poor things having to starve. If the bowls are empty they will go to a Sim and ask them to feed them, which prompts the Sim to refill the bowl, but I micromanage my Sims so much that they are rarely free to be asked by the pet.

Number of pets is completely based on family. I rarely have more than two. While I know pets are as much code and pixels as the Sims are, I've always been weird in that I care more for pets than humans, and that follows into my simming. If my Sims have pets, they have to take care of them and pay attention, I feel bad if they are just sort of there with no attention. Two pets is about as much as my Sims can manage in that situation. I have one breeder though who currently has 7 dogs, and 4 cats. I usually give pets to a Sim who wishes for them, has a high interest in animals, or has a kid. I grew up with pets, and I like my sim-kids to have the same lovely experience I did.

I deal with population control by not breeding my pets. I don't see the need for every pet to have offspring. The breeder Sim will be breeding pets and selling them in her business, but she'll be the only one. And the pets she sells won't be used for breeding, just as family pets, so I'll just be sure not to breed more pets than I have households needing pets.

No sure about family trees and breeding. Never tried it, but I know it's been asked a bunch of times in Stupid Questions-thread. I seem to recall reading it follows the same rules as for Sims, but I could be wrong. Should be easy enough to search the thread and find the answer

I don't have a pet breeder in my hood so the situation would be a bit different. Mine is more of a legacy style, where the families who have pets will breed one of the litter each generation, so an average is 4 pets and occasionally litters (the parents, one of their puppies/kitten and new cas-pet mate). The families who own are relative small, so I wont need large houses, but thinking of giving some of the pets a place to live in the garden and on the first floor. But due to that the game gave them too long lifespan, I plan to manually aging them up occasionally.

Gummilut, I was also raised up around pets. Right now, Ive five cats. Before I had two guenia/mini pigs and hamsters as well. -.- living on the country side and having a mother who is crazy about them. But my real life experience doesnt affect my TS2 gameplay. :P

I'd say you are pretty much screwed in terms of population control, if you expect to breed one pet per generation in each household, and play every pet produced. But hey, if that's how you enjoy your game then that's your business

4 pets per household and one litter per household... yep population explosion with your pets coming up.

Firstly small pets are also pets and don't breed, so think about some people simply having a bird or a wormrat. Only give some families one pet or don't breed. Look to their interests, if they have no interest in animals don't breed them.

Gummilut/JoandSarah.

I was refering to pets in three different generation - the founder cas pets, one of their litters and an non-blood related pet who will later mate with the 2nd generation pet.
Eventually, the elder pets will die so I will later only have 2 pets plus litter. The litter will be moved to other households as soon they reach adults, which in my game, 4 sim days, little more than one rotation. I'll however restrict myself to one litter per pet "couple" (uh, I don't know what you call those, you know, when they have the "mine" flag. )

If you want to keep population down then let some sims adopt strays (the ones who just want a pet and not to breed) and put in Pescado's nostrayrespawn. That will cut down on the numbers you need.

If you have more than one pet more than one food bowl is essential as they can claim a bowl as their own and get pissed off when someone else uses it. For sanity, seeing as you haven't played with pets before, get Pescado's lesspetwarfare. It stops them going batshit crazy doing nothing but attack each other.

You can only fit one pet in a bed (yes, even puppies/kittens), but for space saving Paladin at Sim Wardrobe has one tile pet beds that need less room.

For cats make sure you have a scratching post and for dogs a chew toy.
Praise them as soon as you see a behavior you like such as the dog chewing his toy not the furniture.
To breed pets a sim must first have a good relationship to one of the pets and the two pets must also have a high relationship score with each other. If neither pet is busy have your sim click on a pet and select have kitten/puppies with. They will need a kennel, cats or dogs for them to go try for puppies or kittens. Most pets seem to get pregnant on first try, but sometimes it might take 2 or 3 goes.
Make sure you add in the pet pregnancy token fix as pet pregnancy tokens can easily get stuck. http://linna.modthesims.info/download.php?t=326049
There is also a mod so a pet can sleep on a bed at the same time as a child. http://modthesims.info/d/407570

I've the pregnancy token and I think Ive the sleep bed as well which I downloaded them recently because Im trying to use that EP a little bit more to make these tiny households more fun to play, I haven´t play with pets much other than raising them in the maxi hoods long ago but I did remember, the bowl and beds were always annoying, so I gave up.

Charity; I will check out the one tile pet bed later (using my dad's work laptop and don't have the game there. -_- my laptop charger is broken. ).

Best pet CC ever: The invisible one-tile pet bed! http://www.modthesims.info/download.php?t=518144

Use move objects to place two of them overlapping a two-tile pet bed, and two pets (or two toddlers, or a toddler and a pet) can share it! Martin Gorey's alien hybrid son crawled into one after the disaster, when everyone was too strung out to look after him properly, and the kitten climbed in with him. It looked like the kitten curled up on his chest! I almost melted.

I will download it when my laptop charger is fixed. Having 5-8 pet beds just because the maxi didnt allow them to sleep together is just silly and annoying. (the extra puppies/kitten of the litter wont be in the household for very long but still, it take up too much place).

You can fit up to three pets in one bed with the invis pet bed (although if they're big then it will be a squash XD).

I've been trying to work out lately how to breed pets, because soooo many sims get a want to have pets/puppies/kittens.
So far I have 2 families of breeding pairs:
Kevin Beare's two dogs Shawn (sheep dog) and Catie (can't remember) - who produce mutt-like looking dogs
The Monty family's wolf Beasley and dog Abbey - who produce Husky-looking dogs.
These 2 breeding pairs can produce as many litters as they want (though I do limit it to when I feel there is a need for more animals)
Their litters are then sold to families who want dogs.

With cats I have 2 families:
The Tri-cou clan who have 2 cats Jack-O and Fright - who produce black cats with large ears and big blue/green eyes
Tara Kat's four cats - two breeding pairs - Samantha and Mickey (who seem to produce gingery kittens) and Feline & Camel (1 of Samantha & Mickey's offspring)

If a family already has a pet (either one they've already been given by another family or I've been playing Pepe's pets community lot long enough for sims to buy an animal), then they get a pet of the opposite gender and they are allowed to breed 1 litter only.
If a family doesn't have a second pet, at some point they are allowed to use a modded object (the name escapes me) where I pick another pet who has no breeding partner (regardless of gender sometimes) and they produce 1 kitten/puppy - instead of a whole litter.

I imagine it's probably not going to work out in the long-run, but when I have too many animals I can always just cut down by letting each pet only have 1 offspring using the object instead of a whole litter, or only let 1 out of every litter breed.

Also in answer to your other question: Just like sims, pets can't interbreed between parents/siblings/cousins etc.

Three? I've put at least five or six invisible pet beds together, it works, especially for puppies and kittens

If you place two pet bowls on one square (facing different directions) it looks as though the pets are sharing a dish, which is cute. Otherwise only one pet can eat at once. Works with the middle value one, round but solid metal, and works better with the plain designs, not the pictures. To get a sim to fill up all bowls, direct them to fill up one, pause while they're holding the bowl in the air and click on the second bowl.

I keep population down by not letting every family get a pet, and rarely allowing pet breeding. When I do breed pets I have potential homes for the litter. My sims are responsible animal breeders! Thankfully, there is no ACR for pets. I have found that trying to keep breed lines going is hard because you just don't have enough pets without them being too many overall. So I just use CAS to create breeds and then let them mix, which is more fun for me anyway, to see what happens to the genetics. BTW, there is a bug when breeding a large dog with a small dog. The breeds don't mix correctly and you end up with a clone of one of the parents. However Christianlov's Baby Pet Creator does mix the genetics and you can get interesting results that way.