Blindness

Blind boucles cannot see and might also have irritated or missing eyes.

Deafness

Deafness is not visible on the outside of the unicorn, but leaves them unable to hear and may affect their balance as well.

Allergies

Allergies can range from mild to severe. It is not always visible, but can be in the form of runny noses, runny eyes, bumps and hairloss.

Dud

Dud boucles cannot use magic. They can however still acquire MP.

High Metabolism

High metabolism will make your boucle underweight, no matter how much it eats.

Low Metabolism

Low metabolism will make your boucle overweight, no matter how carefully you plan its diet.

Infertility

While not visible, infertility makes the boucle unable to produce offspring. It may also affect their production of hormones.

Runny

Runny boucles constantly have mucus oozing from their nose, eyes and mouth, yuk!

Hairlessness

Hairless boucles do not have any fur on their body, which leaves them very susceptible to the elements as well as insect bites.

Anemia

Anemic boucles have incorrectly shaped red blood cells which cause them to be breathless and fatigued most of the time.
[example soon!]

Epilepsy

Epilepsy causes periodic fits and seizures to a minor or severe degree. 
[example soon!]

Alopecia

Alopectic boucles have partial to full hair loss all over their coat.
[example soon!]

Hornlessness

While they still have bouclite skeleton, hooves and eyes, hornless boucles does not grow a horn. This in turn often leads to shunning by other unicorns, as well as lowered magical ability.

Overgrown Horn

A boucle’s horn continues to grow extra growths that can take up most of their face!

Stunted Horn

Boucles with a stunted horn barely grow more than a little nubbin where their horn should be and are often mocked by other boucles!

Cyclops

This defect causes the boucle to only have one eye just below their horn!

Triclops

This defect causes the boucle to have an extra eye just below their horn!

Deformed

Boucles with this BD can be deformed in a variety of ways, and they are always moderately to severely affected by their deformities.

Hermaphrodites

While not always visible on the outside, hermaphrodite boucles have parts of the genitalia associated with both genders. They are most often infertile, but a few with one set of genitalia functioning have been found. No inbred hermaphrodite have ever had both sets of genitalia functioning.

Corruption is an incredibly rare group of birth defects, and their ways of expressing is largely unknown. It seem to warp the bodies and sometimes the minds of the boucles, and while they do not have special magic types or abilities some seem to be prone to their magic backfiring. 

A corrupted Boucle will always reflect the phenotype it has, so for example a corrupted muffet would have a spider theme!

If an Ancients Blessing is bestowed upon a corrupted boucle, the Corrupted defect is removed!