A puppy with cyclopia was born in Chachoengsao, central Thailand, on Sunday, 02/02/2020. Despite only having one eye, “Kevin,” as the newborn dog has been named, appears otherwise healthy. Owner Somjai Phummaman, 45, and his family are bottle feeding the puppy.
Cyclopia occurs in many different species. It happens, according to Wikipedia, to roughly one in every 16,000 animals born. The birth defect results from failure of something called the embryonic prosencephalon or forebrain area to divide the orbits of the eye into two cavities.
Here are two graphs showing how the forebrain (left side top of graphs) is supposed to divide normally as an animal develops.
In addition to genetic defects, certain toxins can misdirect the process of embryonic forebrain division.
For example, it is now known that a particular highly teratogenic alkaloid toxin can cause cyclopia. The toxin known as cyclopamine or 2-deoxyjervine, is found in the plant Veratrum californicum more commonly known as corn lily or false hellebore.
Grazing animals such as goats and pigs are most likely to ingest this plant and to induce cyclopia in offspring.
It is a source of jervine, muldamine and cyclopamine, teratogens which can cause prolonged gestation associated with birth defects such as holoprosencephaly and cyclopia in animals such as sheep, horses, and other mammals that graze upon it. These substances inhibit the hedgehog signaling pathway.
A gene regulator with the interesting name Sonic Hedgehog (SHH) is involved, during embryonic development, in the separation of the single eye field into two bilateral fields. Scientists have observed that if this particular gene is mutated, cyclopia, a single eye in the center of an animal’s face, will result.
No one has asked the family, as far as we know, if the dog who gave birth to Kevin could have been exposed to a poisonous plant, but there are other causes as well.
Another recent example of this type of birth defect resulted in what we called a “wookie goat” in India.
Good luck to Kevin, the Thai cyclops puppy.