The cephalic index or cranial index is a number obtained by taking the maximum width of the head of an organism, multiplying it by 100 and then dividing it by their maximum length. The index was once used to categorize human beings in the first half of the 20th century, but today it is used to categorize dogs and cats.
The children of the Tsar Nicholas II of Russia in June 1917, with loss of hair after fighting measles: among them, Tatiana had the skull with least cephalic index.
Brachycephalic French Bulldog, with visible indications of laboured breathing.
Craniofacial angle of a Boxer
Breeds with less extreme brachycephalia, such as the Boxer, have less compromised thermoregulation and thus are more tolerant of vigorous exercise and heat.
Anders Adolph Retzius, was a Swedish professor of anatomy and a supervisor at the Karolinska Institute in Stockholm.
Anders Retzius, by Jean Haagen [sv] (copy of an original by an unknown artist)