There is not much known about the history of the Pugs. But it is certain the Pugs originated in China centuries ago. Pugs, and many other short-nosed breeds, were the favored canine by the Chinese Emperors as early as the 1st century. The pugs we know today originate from England. In the 16th century, the earliest pugs arrived in England.
The Pugs make a wonderful house pet, but there are things a potential need to know and understand about a Pugs health and well being.
"A DOG'S FACE"
There are two types of faces dogs have, there are narrow skulls with a long faces, and a wide skull with a short face. The pug has a wide skull and a small face, with protruding eyes. The pug has 42 teeth, six pairs of incisor teeth in the front of the mouth, flanked by two pairs of large canine teeth. The other teeth are premolars and molars. The canines and incisors are the most important teeth, because dogs use those to cut and tear their food apart. 
The air that the dog breaths in through the nose will travel to the lungs trough two nasal cavities behind the nose. The cavities are lined with a mucous membrane containing many nerve endings stimulated by odors. The reason why a dog sniffs the air, the ground, and the objects nearby, is because they are finding out what happened in the area. 
A dog's tongue is fairly thin because it is used to guide food to the throat, for licking their coat clean, and for respiration. A dog will hang its tongue out when it is overheated, as this helps them cool down. Also the dog will sweat through the pads on its feet and slightly through its skin. 
A dog's eyes have a total of three eyelids. There are the main upper and lower lid, and a third eyelid hidden between them. The third eyelid acts a windshield wiper, as it is able to sweep over the transparent cornea and clean it. 
"A DOG'S BODY"
The dog's torso contains most of the vital organs. The organs are: the heart, lungs, stomach, and intestines, sex organs, kidneys, and bladder. Dogs have a total of 13 ribs that wrap around the lungs, and the heart. From the skull to the end of the dog's tail are a total of 27 bones. The amount of bones the dog has in its tail depends on the breed. The dog's body is covered by straight, or wavy hair. The hair shafts come out from tiny follicles, which are connected to muscles that cause the dog's hair to stand up, or bristle, when they contract. 
"A DOG'S LEGS"
The legs on a dog are used for many different things like movement, scratching, and in some breeds, digging. Dogs also use their legs, or paws to groom themselves. 
The forelimbs are connected to the body by a long, narrow scapula, or shoulder blade. The lower part forms a shoulder joint with the Humerus bone. The Radius and Ulna, and the low forelimbs, are fused at two points to make it look like it is one bone. 
The paw contains five toes. The Dewclaw is like a thumb, and is too high for any use. Usually this claw is removed by vets when the dog is a puppy. The dog's toes are composed of a number of bones. The claw emerges from the end of each toe. Each toe there is a cushioned pad, and farther up the paw, are two large pads. 
Sexually mature female dog have a period of time where they ovulate and become receptive to male dogs, and can get pregnant. This heat cycle of time is called the estrus cycle or heat. The period is about every 7 months, and lasts about 3 weeks. In week one, the females' vulva swells and secretes blood and aromas that drive males into frenzies. During this period, the female will become very moody to people and other dogs. The female may also tease the males cruelly by lifting her tail and letting the males get a sniff of her odor; but when the male to tries to mount her, she will bite their head off. In week two, the female is in true estrus, the vulva will still be swollen, and the vaginal discharge will stop showing visible blood. If the female gets mounted by different males, then the litter will have different characteristics. In week three, the last stage of beginning heat, the female has already ovulated, and is not interested in sex, but males will still be determined. 
There are many things you should know about a Pug's body, before you choose to own one. Five main areas are: the feet, the nails, the ears, the eyes, and the respiratory system. The nails on the Pug need to be trimmed frequently to avoid any problems. The pads on the Pug's feet should be inspected to make sure that there are no cuts on the pads. If you find cuts on the Pug's feet, you should be sure to get them looked at. If you don’t, it will inflict a lot of pain on the Pug. If the feet aren’t looked at, the pads may become infected. The ears on a Pug are called button ears, which mean the ears are folded over, as if they were buttoned down. If the ears aren't cleaned frequently the ears become a lovely place for ear mites to live. The ears should be cleaned with an approved ear wash and used frequently on the ears to help prevent problems. The other place to watch closely is the eyes. The eyes protrude from the Pug's face and are really big. Because the eyes protrude out from the Pug's flat face you may end up with eye ulcers. If your Pug starts to scratch its eyes you should take your pug into the vet right away to make sure that it doesn't have an eye ulcer. Because the Pug's face is flat, the nose is scrunched up and the wind pipes get closed off, which make it hard for the Pug to breath. This isn't a big problem for younger Pugs, but if you have an older dog you should let your vet take a look. 
If you are thinking about breeding these wonderful dogs, something you want to do before you actually breed them, is to make sure that the dog's health is good. You don't want the mom or dad passing the bad health onto the little ones. If you own a female you, its best to breed her after she is about 2 years old, and has experienced two heat seasons. A heat season lasts about 28 days. The best time to start the breeding process is about 2 to 3 weeks into the season, because that is when they have best vaginal discharge.