Molera
Encyclopedia
A molera is a "hole" in a Chihuahua
's head; it is the same as a fontanelle
in human babies. Historically, the Chihuahua as developed in Mexico
and the United States
has displayed a "hole in the head". In times past, this has been accepted as a mark of purity for this dog breed
, and it is still mentioned in most Chihuahua breed standards the world over. The bones of the head in all foetuses are not firmly knitted together, but in most mammals, the different bones of the skull join with cartilaginous sutures as the animal matures. The Chihuahuas' moleras vary in size and shape, occurring on the top of the head where the parietal and frontal bones come together.
The simple fact that a Chihuahua has a domed head with an open molera does not predispose it to hydrocephalus
as found by a study done by Greene and Braund in 1989, which concluded that "Many clinically normal toy breeds and brachycephalic (short faced) breeds also may have open fontanelles without associated hydrocephalus
." Also, "There did not appear to be any relationship between the presence or size of the fontanelle and the concomitant presence of hydrocephalus." When the dog seems normal but displays enlarged ventricles of the brain (under ultrasound), its hydrocephalus is termed "occult" (having no clinical signs).
Chihuahua (dog)
The ' is the smallest breed of dog and is so named for the state of Chihuahua in Mexico. Chihuahuas come in a wide variety of sizes, head shapes, colors and coat lengths.-History:...
's head; it is the same as a fontanelle
Fontanelle
A fontanelle is an anatomical feature on an infant's skull.-Anatomy:Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the...
in human babies. Historically, the Chihuahua as developed in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
has displayed a "hole in the head". In times past, this has been accepted as a mark of purity for this dog breed
Dog breed
Dog breeds are groups of closely related and visibly similar domestic dogs, which are all of the subspecies Canis lupus familiaris, having characteristic traits that are selected and maintained by humans, bred from a known foundation stock....
, and it is still mentioned in most Chihuahua breed standards the world over. The bones of the head in all foetuses are not firmly knitted together, but in most mammals, the different bones of the skull join with cartilaginous sutures as the animal matures. The Chihuahuas' moleras vary in size and shape, occurring on the top of the head where the parietal and frontal bones come together.
The simple fact that a Chihuahua has a domed head with an open molera does not predispose it to hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
as found by a study done by Greene and Braund in 1989, which concluded that "Many clinically normal toy breeds and brachycephalic (short faced) breeds also may have open fontanelles without associated hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
." Also, "There did not appear to be any relationship between the presence or size of the fontanelle and the concomitant presence of hydrocephalus." When the dog seems normal but displays enlarged ventricles of the brain (under ultrasound), its hydrocephalus is termed "occult" (having no clinical signs).