Bundled with Yagami Hiroki's G-Best -G-Taste Best Selection compilation manga volume. The 64-page volume collected selected stories from original full-colour erotic manga series, which ran in Young Magazine Uppers.

Why don't we see mentally challenged animals?

There are actually many cases of mentally challenged animals, we just do not see them in the frequency we see mentally challenged people.
It makes sense that we don’t.
For one thing, wild animals born with disabilities are more likely to be abandoned by their parents.
Even if they aren’t, the odds of a disabled wild animal making it past infancy without human intervention are very slim.
Likewise, mentally challenged animals are similar to mentally challenged people in that being born with a debilitating condition is rare. A responsible breeder takes careful consideration for the animals involved.
In dogs, for example, a decent breeder will only breed animals once or twice a year and the breeding pair will have blood lines as far apart as possible.
The fewer puppies born, the smaller the likelihood of a mentally challenged puppy being born.
In contrast, irresponsible breeders such as owners of puppy farms, prioritize profit more than the health of animals.
Puppy mills crank out puppies from dusk ‘till dawn.
The dogs are bred and bred until they are spent, in which case they are usually discarded in dispicable ways. Dogs are often inbred.
The combination of poor genetics and high frequency breeding increases the chance of a mentally disabled puppy being born.
Additionally, whereas a good breeder may take great care of newborn puppies, usually being present to help during labor, and willing to provide medical care for all their puppies, a puppy mill owner is not as caring.
Mentally challenged puppies born into a puppy mill will most likely not have any care after being born.
Mentally disabled human infants often need special care from hospital staff immediately after being born.
A puppy mill owner is more likely to “take care” of a disabled puppy or let the animal die should the mother abandon it.
By comparison, once a human being is born (and many people agree before that) the parents and hospital staff have a duty to see that that child survives.
Animals are not bound to infants or preservation of life in the same way human parents are and owners of animals often choose cruelty over inconvenience. I should clarify that Down syndrome is a human condition and isn’t found in other species except chimpanzees, and then only very rarely.
That being said, variations or similarities of Down syndrome may be found in other species.
Chat Q&A: Can animals get down syndrome? Here are some mentally challenged animals: 10 animals with down syndrome that will warm your heart