The pug is a "toy" (very small) breed of dog with a wrinkly, short-muzzled face, and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, and a compact square body with well-developed muscle. They have been described as multum in parvo ("much in little"), referring to the pug's personality and small size. Known in ancient China as lo-sze, they may have been responsible for both the modern Pekingese and King Charles spaniel. They have Chinese origins, but were popularized in Western Europe by the House of Orange of the Netherlands and the House of Stuart of England, Ireland and Scotland
The breed is often summarized as multum in parvo ("much in little"), describing the pug's remarkable personality despite its small size. While the pugs appearing in eighteenth century prints tended to be long and lean, modern breed preferences are for a square, cobby body, a compact form, a deep chest, and well-developed muscle. Pugs have two distinct shapes for their ears, "rose" and "button". "Rose" ears are smaller than the standard style "button" and are folded with the front edge against the side of the head. Breeding preference goes to "button" style pugs. The legs are very strong, straight, of moderate length, and are set well under. The shoulders are moderately laid back. The pasterns are strong, neither steep nor down. The feet are neither so long as the foot of the hare, nor so round as that of the cat; well split-up toes, and the nails black. The lower teeth normally protrude further than their upper, meeting in an under-bite.
Their smooth, glossy coats can be fawn, apricot fawn, silver, brindle or black. There is also the rarer white pug which gets its coat via breeding or albinism. A silver coat is characterized by a very light coloured coat, absent of black guard hairs. A silver pug typically has a very dark head, with no clear delineation at the mask, and dark forelegs. The markings are clearly defined. The trace is a black line extending from the occiput to the tail. The tail normally curls tightly over the hip.
Strong willed but rarely aggressive, the pug is suitable for families with children. The majority of the breed is very fond of children and sturdy enough to properly play with them. They can be quiet and docile but also vivacious and teasing depending on their owner's mood. They apparently make good watchdogs; although they are always alert and sometimes yappy.
Bred to adorn the laps of the Chinese sovereigns during the Shang dynasty (before 400 BCE). They were known as "Lo-Chiang-Sze" or "Foo" (ceramic foos, transmogrified into dragon, with their bulging eyes are similar in appearance to the pug). References to pug-like dogs have been documented as early as 551 BCE by Confucius, who described a type of "short mouthed dog". The lo-sze or early pug may have been the predecessor of today's modern Pekingese. The pug's popularity spread to Tibet, where they were mainly kept by Buddhist monks, and then went on to Japan, and finally Europe. The exact origins of the pug are unknown, as Emperor Qin Shi Huang, the first Emperor of China, destroyed all records, scrolls and art related to the pug at some point during his reign which lasted between 221 and 210 BCE. Chinese fu dogs, also called lion dogs or fo dogs, were thought of as guardians and statues of them were placed outside temples. The faces of these statues resemble Oriental short-faced dogs, such as the Japanese chin Tibetan Spaniel, Lhasa apso, Pekinese and the pug.
Since pugs lack longer snouts and prominent skeletal brow ridges, they are susceptible to eye injuries such as proptosis and scratched corneas and painful entropion. They also have compact breathing passageways, leaving many unable to breathe properly or efficiently regulate their temperature through evaporation from the tongue. A pug's normal body temperature is between 101 °F (38 °C) and 102 °F (39 °C). If the temperature rises to 105 °F (41 °C) they are no longer able to cope with cooling themselves and their oxygen demand is greatly increased, and requires cooling down immediately. Should the temperature reach 108 °F (42 °C), the internal organs begin to break down at a cellular level which can lead to severe long term health issues or even death.
Pugs living a mostly sedentary life can be prone to obesity, though this is avoidable with regular exercise and a healthy diet. A UK Kennel Club survey puts the average life span of Pugs at 10 years.
An investigative documentary carried out by the BBC found significant inbreeding between pedigree dogs, with a study by Imperial College, London, showing that the 10,000 pugs in the UK are so inbred that their gene pool is the equivalent of only 50 individuals.