That would be the Chihuahua. Chihuahuas are very cute! Let me give you some information about Chihuahuas: Chihuahua (Chihuahua) has an unclear history from its arrival in the United States from Mexico until 1898. Some confirm this dog originally came from South America, initially regarded as a sacred dog breed by the Inca people, later passed to the Aztecs. Some also believe this dog came to the New World with Spanish invaders or was introduced from China in the early 19th century.
In short, the exact origin of the Chihuahua is disputed. These imaginative bases come from Toltec-era monastery statues and small dog skeletons excavated in Mexico. According to dog images on Chinese crowns, it is believed this dog came from distant Asia. All these judgments indicate that this dog was never derived from a single breed but has been bred from multiple breeds since ancient times.
　　Introduction　　 Chihuahuas are the smallest among small dog breeds, elegant, alert, quick in movement, and widely loved for their well-proportioned physique and petite size. Chihuahua dogs are not only cute small toy dogs but also possess the hunting and protective instincts of large dogs, with a temperament similar to terriers. There are long-haired and short-haired varieties. This dog is tiny, not afraid of other dogs, and very possessive towards its owner.
The difference between short-haired and long-haired types is that the short-haired coat is shiny, close-fitting, and smooth. The long-haired Chihuahua has thick back hair and, like the short-haired type, tends to shiver—this should not be mistaken for a cold.　　 The smallest dog breed in the world is the Chihuahua. Also known as the Chiwawa or Qihuahua ornamental dog.　　 Origin: Mexico, Chihuahua state.　　 Height: 12–20 cm, the smaller the more loved.
　　 Weight: 0.5–2.7 kg.　　 History: The Chihuahua developed around the 19th century from dogs raised by the Mexican Toltec people. The Chihuahua Dog Club was established in 1923 and is one of the 12 most popular dog breeds in the United States. The UK Chihuahua Club was founded in 1949.　　 Features: Chihuahua is the smallest dog breed in the world, with a round head, large thin upright ears, and large round eyes.
There are short-haired and long-haired types of Chihuahuas.　　 Personality: The Chihuahua has a strong will, is intelligent and extremely loyal, agile, lively, very brave, and able to defend itself against large dogs. They are quite cold-sensitive and not suitable for outdoor kennels. In winter, they need to wear coats when going outside.　　 Coat color and quality: Cream, red, brown, black with yellowish-brown. The short-haired variety has a soft coat.
The long-haired type has decorative fur on the ears, limbs, and tail, with the coat length not touching the ground. Long-haired Chihuahuas are more sensitive to cold.　　 Size: The weight should not exceed 6 pounds. The body proportion is rectangular; hence the length from shoulder to rump is slightly greater than shoulder height. Males with a slightly shorter body are preferred. Weighing more than 6 pounds is disqualifying.　　 Head: Preferably a round "apple-shaped" head.
Bright expression. Eyes are large but not protruding, symmetrical, preferably bright black or red (dogs of pale yellow or white color may have white eyes). Ears are large, erect, standing straighter when alert but open at about a 45-degree angle when resting. Muzzle is short and slightly pointed. Nose colors of black, blue, and chocolate varieties match their coat colors.
Yellowish-colored dogs may have pink noses. Scissor or pincer bite. Overbite or underbite are serious faults. Cropped ears will disqualify from competition.　　 Neck, topline, body　　 The neck is slightly curved and connects perfectly with the shoulders. The topline is level. Rounded ribs support the chest, making the body strong and solid (but not barrel-chested). The tail is moderately long, sickle-shaped, carried high or outwards, or curled over the back, with the tip just touching the back (never tucked between the legs).
Short or docked tails are disqualifying.　　 Forelimbs should be narrow at the shoulder, gradually widening downwards. The front legs are straight, allowing free elbow movement. Shoulders should be upright, balanced, and solid, slanting towards the back (shoulders should not be low or downward). Broad chest and strong front half of the body but never like a "bulldog's" chest. Feet are slender, with toes nicely separated on graceful small feet but not too separated; footpads are thick (not like rabbit or cat feet).
Wrists are slender.　　 Hind limbs: Muscular, properly spaced—not too close or too wide—when viewed from behind, strong and solid. Feet same as forelimbs.　　 [Coat] The short-haired type has very soft, tight, and smooth fur (undercoat allowed when the coat is thick enough). The coat covers the body with a good mane and tail, and sparse hair on head and ears. Tail fur resembles soft leather. The long-haired type has soft, flat, or slightly wavy fur, preferably with undercoat.
Decorative hair is present on ear edges (if the ear is thin and has many decorative hairs, the ear might tilt slightly forward but never downward). The tail is full and long (feathered). Ideally, there is decorative hair on legs and feet, "pants" on the hindquarters, and a mane around the neck. Disqualifications for long-haired type: sparse or nearly bald coat.　　 Color: Any color, patches, or spots allowed.　　 Gait: Chihuahuas move quickly and firmly, with strong hindquarter drive.
Viewed from behind, the hind legs are always parallel, and hind foot placements closely follow the forefeet. Both fore and hind legs tend to align slightly toward the center of gravity to increase speed. Viewed from the side, forequarters guide and join the driving rear quarters, with a proud head and brisk steps. The topline is kept level and steady in motion. Elegant and effortless, forelimbs extend strongly, and hindquarters provide powerful thrust. From the side, stride length is appropriate; from front and back, movement is straight-lined, thanks to sound bone and muscle structure.
　　 Personality: Alert, with a terrier-like temperament. [Disqualifications] Weight over 6 pounds; ears not erect or cropped; short or docked tail; sparse or nearly bald coat in long-haired types.　　 Care points: Chihuahuas are lively and active and should not be confined indoors all day; their coats should be brushed with a soft brush and wiped with velvet cloth to shine; ears must be cleaned regularly; nails should be trimmed routinely; these dogs have fragile bones, so avoid jumping from high places to prevent fractures.
Chihuahuas are naughty and active, often running around at home showing joyful expressions, so owners should moderate this behavior. They are cold-sensitive; catching cold may cause pneumonia and rheumatic arthritis. In winter, they need to wear a dog coat when outside for warmth.　　 Health: Chihuahuas require special veterinary care at birth and dental care. They often suffer from some hereditary neurological diseases like epilepsy and linked with patellar luxation problems. Also well-known is their skull’s fontanelle—meaning incomplete skull closure, leaving a small hole on top of the head.
　　 Chihuahua raising and management methods　　 Many people like keeping Chihuahuas because they are not demanding about living environments or food, making them relatively easy to rear and manage. However, attention is still needed.
（1）Hygiene　　 Even though Chihuahuas mostly stay indoors, cleaning is necessary.
They should be bathed at least once a month. Long-haired Chihuahuas need more frequent baths because their long fur easily collects dirt. Coat should be regularly brushed with a soft brush and wiped with velvet cloth for shine. Ears should be cleaned regularly. Also, Chihuahua nails grow quickly and are slender, so regular trimming is essential.
　　 （2）Food　　 The food must be clean, hygienic, and fresh. Feeding bowls must be cleaned regularly, and fresh water supplied after meals.
Chihuahuas naturally eat small amounts but have a fast metabolism, often feeling hungry, so feeding several small meals a day is best. Dry food should be the primary diet, with moderate addition of wet food.
They love to eat but care must be taken to avoid overfeeding to prevent obesity.
Daily 60-90 grams of meat is sufficient; larger Chihuahuas require about 150 grams, plus a similar amount of vegetables and biscuits.
Since they dislike cold, food should be warm. Meat should be cooked, chopped finely, mixed with dry food and warm water before feeding.
　　 （3）Environment　　 Chihuahuas are small with low space needs, so normal living spaces suffice for playing. Their daily exercise requirements are low, and they don't need frequent outdoor playtime. They are very suitable for people living in apartments and can stay indoors all day.
Chihuahuas are not suitable for outdoor living because extreme heat or cold easily make them sick.
Owners should take them outside for walks on pleasant days to enjoy sunlight and a bit of sunbathing. They fear cold, and catching cold can cause pneumonia and rheumatic arthritis, so warming them in winter is critical.
　　 （4）House training　　 When a dog urinates or defecates indoors, first determine if it has received consistent house training; if not, the owner must retrain.
Sometimes, a dog with prior house training may have diarrhea and relieve itself indoors, then start repeatedly soiling the same spot. At this time, the owner should restrict the dog's access to that area and retrain the dog with proper habits.