do animals have "teen" pregnancies?

That is, do females of other species become biologically capable of pregnancy before they’ve reached full growth and maturity?

As in do animals of other species become pregnant after reaching sexual maturity but before literally growing physically as much as they can? Yes. In fact, that’s the norm for all of them.

Yes, this is a big problem in dogs, and likely cats. Real breeders usually wait until a female is at least 2 before breeding. Many dog owners are incredible ignorant about canine reproduction. I have seen questions on dog forums many times ‘‘Why is my dog bleeding from its vagina?’’. People buy a female puppy having no clue what they need to do to avoid pregnancy late in its first year, long before it is best. Others have no idea of the strenuous, creative efforts dogs, including the the female, will make to get together to mate.

Spaying females in season or pregnant is messy and most vets don’t like to do it.

Such pregnancies contribute to the millions of dogs slaughtered every year for lack of homes.

When I was a kid we adopted two kittens, brother and sister. At the time the general philosophy was that you spayed/neutered at 6 months. Well, brother got sister pregnant well before that, leading to a miscarriage of 13 kittens, some of which had to be extracted at the vet’s office.

So I’d say yes, “teen” pregnancy is possible, and possibly common, among other animals. At least cats.

Remember that the evolutionary process tends to optimize organisms for successful reproduction on average.

It may be somewhat dangerous to individual females of a species to become sexually mature before they’re fully physically mature. But if that trait results in more reproductive throughput for the species as a whole, then the individuals carrying that trait will end up dominating the population.

The fact that, say, human females can become sexually mature at about thirteen although they’re not fully physically and psychologically mature until about eighteen means they’ve got a five-year head start in producing offspring. Yes, some young teen mothers will die or become infertile as a result of early pregnancy, but as long as most of them don’t, then teen pregnancy is a better deal for the species as a whole in evolutionary terms.

Cats are famous, or infamous, for going into heat before they’re really mature enough to start having kittens. I had a cat who got pregnant at the ripe old age of six months. Now she and her kittens all lived, but you had better believe that nowadays I get all my pets spayed and neutered as soon as a vet will do the operation.

On the old AOL SDMB, we had a woman who had a very small male dog and a very large female dog, both intact. I believe she was a breeder. At any rate, when the bitch went into heat, this woman figured that the height difference was too great, and that the male didn’t know where the nearest stepladder was. She said that “the hussy laid down for him”, and the bitch did indeed get knocked up.

Horses are generally considered physically mature at 4, but are often still developing bone and muscle until age five or six. (A four year old horse is roughly the equivalent of a 21 year old human - sure, they’re physically an adult, but the body isn’t fully mature until 25 or 26.) Young female horses (fillies) can get pregnant as young as one year of age, and the young males (colts) can ‘do the deed’ as early as eight months. This is the equivalent of a nine year old human with his first boner. So at least among horses, premature pregnancy is quite possible. Fortunately equine abortions are pretty easy during the first few months.

How this works out in the wild where there are no humans stopping a premature breeding, I really don’t know. There must be some evolutionary advantage to females that are fertile before they can safely carry a pregnancy to term, but I can’t imagine what. (Edit: just saw Kimstu’s post. That’s right, evolution has to be considered from a societal perspective, not an individual one. I still don’t completely understand, as it seems like a society where the great majority of females are fertile early and will get pregnant early would be at a disadvantage compared to a society where most aren’t fertile until maturity.)

While they don’t get pregnant per se, young hens are more likely to lay eggs with no yolk or two yolks than mature ones - those eggs would not be viable.

A lot of animals have a season for breeding, especially where there are seasons. This ensures that the animals are mature enough to fend for themselves (or store fat to hibernate) before it’s too late, and don’t have to find food for pregnancy or babies during the winter.

Also, most animals give off cues (go into heat) when they are ready to reproduce. Humans are somewhat odd in that the females deliberately do not show obvious signs of fertile time.

(One theory is that humans evolved that females used the promise of possible fertility to encourage males to provide food. If the female’s fertility status was unknown, the males would be hunting and gathering for them all month long… ;0 )

QFT. One of my cats also had a litter at six months–as soon as she was old enough to. The kittens lived and were adopted out (and Mama turned out to be a great mama to them), but Mama was into the vet for a spaying as soon as the vet said that she was physically able.

Huh. I always wondered whether double and triple yolked eggs were viable. I guess now I can quit wondering.

Regarding the question of premature fertility, is this in any non-domesticated animal?

They don’t get abortions, I’ll tell you that. Every animal I know is pro-life. Frackin’ conservatives.

My uncle used to have hens; the first time one of them nested, one of the eggs they gave her was larger than the usual lay and it ended up being two non-viable chicks. A neighbor who’s a real farmer told him that one of the reasons to know your hens’ individual favorite laying spots (instead of simply “the spots most likely to have an egg”) is to nest only those from mature, not-too-old ones.

I wonder if the same applies to wild animals? Female wolves come into heat about once a year, compared to domestic bitches about twice a year. I just did a fast google, and it appears that lions, tigers etc don’t become sexually mature until they’re two or three years old. Meaning a lioness would be physically and mentally mature when she bears her first litter.

Many years ago I had a young cat. She was about five months old when we left for Christmas, leaving friends house sitting for about ten days. I didn’t realise then that cats can come into heat so young (males are capable of reproduction as young as four months old) and while I planned to have her spayed, I hadn’t done so yet. Plus she was an indoor cat. Until she came into heat and yowled so much my friends let her outside, not realising what the deal was. She bore three kittens, one of which was deformed (but lived, in fact the first one adopted.)

I work with a group that does TNR - trap, neuter, release of stray and feral cats. Their rule of thumb for spay/neuter is as long as the kitten is two months old and weighs two pounds, they’ll proceed. Since domestic cats can come into heat three times a year we make every effort to speuter everything possible in a colony to prevent a constant cycle of pregnancy, nurning, weaning, rinse and repeat.

Note that in social settings, there may be hormonal/societal cues that would discourage early fertility, as well as environmental factors (ie, low energy balance, emaciation, parasitism) that can prevent it.

Cattle is another group where they can breed before fully mature, and in fact, in many places the goal is to have the heifer bred by the time she’s a year old, while she is still on the final stages of her own development. For that, the heifer must have appropriate nutrition before (so that she can start to cycle) and throughout the pregnancy (to support the fetus and finish her own growth).

My understanding of wolves is that all but the alpha female are disciplined not to breed. With the difficulty of controlling dogs, I have wondered about that. Also, in recent years there are new ideas of wolf behavior. I haven’t made up my mind on them. I miss the days when science was more objective.

One of the cats my mom had, we got as a kitten. She got pregnant long before we thought it possible, and the vet said that she probably wouldn’t survive carrying them to term. He said he doesn’t much like doing pregnant spays, but that there wasn’t really an alternative in this case.

It did seem to leave an impression on her psychologically, in that she seemed convinced that she was actually a mother. For the rest of their lives, she treated the smallest of our cats as her kitten, despite that cat being about four years older than her. Oddly, both seemed to find the arrangement satisfactory.

Technically, humans are “wild” or non-domesticated animals: that is, our fertility patterns (including teen pregnancy) evolved spontaneously, without any other species attempting us to breed us for characteristics like early fertility.